TR NEWSNUMBER 262 MAY–JUNE 2009

COVER: The interconnectionbetween transportation and theenvironment raises issues in projectefficiency, historic preservation, andwildlife protection, such as in thecase of the San Joaquin kit fox, anendangered species threatened byvehicle collisions. (Photo: B.Peterson, U.S. Fish and WildlifeService)

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TRANSPORTATION AND THE ENVIRONMENT: MUTUAL ENHANCEMENTS

3 INTRODUCTIONThe Environment and Transportation: Making Both Better Than BeforeMark S. KrossIntegrated transportation systems and environmental solutions are making not onlytransport but the environment better than before. Collaboration associated with contextshas become a hallmark of these efforts, addressing transportation needs throughenvironmentally sensitive solutions assisted by directed research.

4 POINT OF VIEWTransportation and Environmental Sustainability:Taking “Making It Better Than Before” into the FutureRick Record and Andras FeketeThe National Environmental Policy Act has made sustainability part of the transportationdecision-making process; the authors identify continuing principles and call forcollaboration among federal agencies and stakeholders to provide guidance andaccountability for the many efforts launched under stewardship, sustainability, smart growth,context-sensitive solutions, environmental management, and related initiatives.

8 Air Quality Management: Successes and Emerging ChallengesJeffrey Houk and Michael ClaggettSolving the air pollution problems caused by transportation, particularly from highways,has been a focus of policy makers for decades. Research and experience have improvedunderstanding and control of transportation-related air pollution, but new challenges arearising—such as tightened standards for ozone and emissions of particulate matter, as wellas efforts to mitigate and adapt to climate change.

12 Transportation Ecology and Wildlife Passages:The State of the Practice and Science ofMaking Roads Better for WildlifePatricia C. Cramer and John A. BissonetteTransportation ecology focuses on the interactions of organisms and the environment withtransportation infrastructures and vehicles. A major goal is to understand the effects of roadson wildlife populations and to develop measures to assist wildlife over and under roads—toprevent collisions with vehicles and to help wildlife and aquatic species move acrossaccustomed areas.

14 Best Practices for Preventing Wildlife–Vehicle CollisionsPatrick T. McGowen and Marcel P. Huijser

16 Assessing Road Barriers to Aquatic Species:Lessons Learned in the NorthwestMatthew D. Blank

20 Public Outreach on Noise Impacts from Transportation Projects:Communicating and Improving Measures for Transit,Highways, and AirportsHugh Saurenman, Adam Alexander, and Nicholas MillerPublic outreach and land use compatibility are two approaches still evolving to addresstransportation-related noise. The authors present accomplishments, applications, issues, andpractical insights related to the mitigation and control of noise from transit, highway, andairport projects.

22 Arizona Tests Quieter Highway PavementJudith L. Rochat

25 Transportation and Historic Preservation:Progress and ResearchAntony F. Opperman, Hope E. Luhman, Emily Pettis, and Stephanie StoermerAccommodating historic preservation concerns can be a difficult environmentalchallenge for transportation projects. Historic preservation research is working toimprove transportation project delivery and the stewardship of historic assetsinvolved in the transportation system. The authors examine three areas: thedesignation of historic status, the treatment of the recent historic past, and thepreservation of historic bridges.

28 Preserving Bridges Nationwide: Improving on the PastEmily Pettis and Christine Long

30 Introducing Context-Sensitive Solutions to theNext Generation of Transportation ProfessionalsJames B. Martin

TR NEWSTR NEWSfeatures articles on innovative and timelyresearch and development activities in all modesof trans portation. Brief news items of interest tothe transportation community are also included,along with profiles of transportation profes-sionals, meeting an nouncements, summaries ofnew publications, and news of Transportation Re search Board activities.

TR News is produced by theTransportation Research BoardPublications OfficeJavy Awan, Editor and Publications DirectorLea Mae Rice, Assistant EditorJennifer J. Weeks, Photo ResearcherJuanita Green, Production ManagerMichelle Wandres, Graphic Designer

TR News Editorial BoardFrederick D. Hejl, ChairmanJerry A. DiMaggioCharles FayChristine L. GerencherEdward T. HarriganChristopher J. HedgesThomas R. Menzies, Jr.Barbara L. PostG.P. Jayaprakash, Research Pays Off Liaison

Transportation Research BoardRobert E. Skinner, Jr., Executive DirectorSuzanne B. Schneider, Associate Executive

DirectorMark R. Norman, Director,

Technical ActivitiesStephen R. Godwin, Director,

Studies and Special ProgramsMichael P. LaPlante, Director,

Administration and FinanceChristopher W. Jenks, Director,

Cooperative Research ProgramsNeil F. Hawks, Director, SHRP 2

TR News (ISSN 0738-6826) is issued bimonthly by theTransportation Research Board, National ResearchCouncil, 500 Fifth Street, NW, Washington, DC 20001.Internet address: www.TRB.org.

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Notice: The opinions expressed in articles appearingin TR News are those of the authors and do not necessarily reflect the views of the TransportationResearch Board. The Transpor tation Research Boardand TR News do not endorse products or manufac-turers. Trade and manufacturers’ names appear in anarticle only because they are considered essential toits object.

Printed in the United States of America.

Copyright © 2009 Transportation Research Board.All rights reserved.

A L S O I N T H I S I S S U E :

C O M I N G N E X T I S S U E

Road and transportation congestion pricing—the various types in use and proposed, as well astheir motivations—are examined in featurearticles slated for the July–August TR News.Authors look at high-occupancy toll lanes,managed lanes, truck tollways, busways, uses ofrevenue, traffic flow and capacity, nontoll pricing,and tolling technology in the United States andabroad and consider the effects of congestionpricing on emissions reduction in Europe and ontransportation planning practice.

Road prices are posted for MnPASS usersconnecting to I-94 and Highway 100 outside ofdowntown Minneapolis, Minnesota. MnPASSallows solo drivers to use a high-occupancyvehicle lane by paying an electronic toll; fees arebased on traffic levels in the express lanes toensure traffic flows at 50 to 55 miles per hourand on the vehicle’s entrance and exit points.

31 Research Pays OffReducing Underwater Sounds with Air Bubble Curtains:Protecting Fish and Marine Mammals from Pile-Driving NoiseJames A. Reyff

34 ProfilesTraffic management and control technology expert Kenneth G. Courageand geotechnology and geosynthetics expert Robert D. Holtz

36 News BriefsAdjusting spring load restrictions, emissions control initiative in Europe,traffic safety improvements

38 TRB HighlightsCooperative Research Programs News, 38

40 Calendar41 Bookshelf

Trains That Passed in the Night: Author Offers Insights on Photo Exhibit, 42

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THE ENVIRONMENT AND TRANSPORTATION Making Both Better Than Before

T he environment and transportation is the subject of thisspecial issue of TR News, with diverse and informativecontributions from members of the standing technical

committees in the Transportation Research Board’s (TRB) Envi-ronment and Energy Section. The Environmental Analysis inTransportation Committee shepherded the preparation of thearticles, aware of a tradition of milestone special issues in thissubject area: in May–June 1996, on waste and recycling; inJuly–August 2003, on air quality; and in September–October2005, on noise.

Tracing out recent achievements, key developments, newdirections, and research needs in each of the committees’ areasof endeavor, the authors define the theme—and goal—of“making it better than before:”

� Environmental analysis in transportation—Agencies areputting 40 years of environment-related operating proceduresinto contexts of sustainability, increased efficiencies, and sensi-tivities, going beyond any single project or environmental doc-ument.

� Transportation and air quality—Transportation planners,air quality planners, and urban planners are collaborating toaddress transportation air quality conformity, for moreinformed decision making, applying advances in technologyand research.

� Ecology and transportation—The toll of animal–vehiclecollisions is staggering, and ecologists, planners, and infra-structure designers are working together to accommodatetransportation needs and wildlife habitats in upgraded or newfacilities.

� Transportation-related noise and vibration—Noise issuesare being addressed in the contexts of the populations, thenoise levels produced, the generating sources, the mitigationoptions, and the benefits and the disadvantages to entire com-munities.

�Historic and archeological preservation in transporta-tion—Progress is being made in historic preservation related totransportation, and research is clarifying the value achievedand the needs ahead.

In each of the approaches described in these articles, col-laboration associated with contexts is evident as a hallmark—addressing transportation needs successfully through

environmentally sensitive solutions assisted by directedresearch. In addition, a Research Pays Off article showcases thecontribution of practical research and innovation in solving atransportation-related environmental problem, and a sidebararticle from the Center for Transportation and the Environmentpresents a working model for hands-on training in the princi-ples of context-sensitive solutions.

These topics and other current key issues—such as trans-portation funding, climate change and global warming, andinfrastructure maintenance—differ from the issues I encoun-tered starting out in environmental analysis at the MissouriDepartment of Transportation (DOT) in 1986. In the early 1970s,5-page environmental impact statements for urban 4-lane free-ways were prepared by engineers who received project surveyinformation from other state or federal agencies—the issueswere local, and the agencies had the resources to offer surveysfor DOT projects. Multiple regulations about environmentalissues—such as wetlands, threatened and endangered species,environmental justice, and others—emerged in the mid-1970s.In the 1980s and 1990s, each issue received attention in trans-portation planning and design, and integration of theapproaches led to more sensitive project solutions. In the 2000s,the approaches of collaboration with stakeholders and of apply-ing diverse but integrated solutions advanced, along with abroader focus—looking “beyond the right-of-way”—on toregional and global issues and practical, yet sensitive, solutions.

More than transportation solutions and projects now areaccommodating the environment—integrated transportationsystems and environmental solutions are making not only trans-port but also the environment better than before—as docu-mented in the articles in this issue.

—Mark S. KrossImmediate Past Chair, TRB Environmental

Analysis in Transportation CommitteeJefferson City, Missouri

EDITOR’S NOTE: Acknowledgment and appreciation are dueto Charles (Muggs) Stoll, San Diego Association of Gov-ernments, who shepherded this issue of TR News as amember of the Environmental Analysis in TransportationCommittee and now serves as committee chair, and toTRB Senior Program Officer Christopher J. Hedges for hisguidance and advice.

INTRODUCTION

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Record is Principal, RLRecord LLC, Cincinnati,Ohio, and Fekete isManager, SpecialProjects, RBA Group,Parsippany, New Jersey.

The word “sustainability” shows up increas-ingly in every sector of transportation practice, from planning to pavement main-

tenance. The word raises expectations in regulators,elected officials, citizens, and interest groups—andthose expectations are not limited to transportation.Economics, residential and commercial develop-ment, energy policy, agricultural practices, industrialmanagement, and business philosophy are beingshaped by expectations for a sustainable fit with theenvironment.

The U.S. federal transportation program, a high-visibility translation of public policy, is in the spot-light on this issue. Because of distinct expectationsestablished by the National Environmental PolicyAct (NEPA) of 1969, sustainability is part of the

transportation decision-making process.1 Practition-ers and policy makers, however, have not always rec-ognized or worked effectively with the many issues,components, and opportunities under NEPA’s sus-tainability banner.

NEPA: 40 Years of ProgressBroad in scope and visionary in scale, NEPA was eas-ily misinterpreted and commonly misunderstood in

POINT OF VIEW

Transportation and Environmental SustainabilityTaking “Making It Better Than Before” into the Future

RICK RECORD AND ANDRAS FEKETE

THE ENVIRONMENT AND TRANSPORTATION Making Both Better Than Before

1 Section 101 of the National Environmental Policy Act of1969 requires the “federal government, in cooperation withstate and local governments…to use all practicable meansand measures…to create and maintain conditions underwhich man and nature can exist in productive harmony,and fulfill the social, economic, and other requirements ofpresent and future generations of Americans.”

The environmental studyfor LA-1, which connectsGolden Meadow,Louisiana, to PortFourchon on the Gulf ofMexico, took only 44months from start tofinish.

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its early years. Transportation—particularly relatingto highways—offered perhaps the most difficult chal-lenges. When NEPA arrived, the Interstate highwayprogram was 14 years old, and roughly 70 percent ofthe system in place today already had been built.

Transportation’s successes as of the mid-1970smade it hard to discern how environmental regula-tions could add value to the highway program. As aresult, the first two decades and more of NEPA intransportation were characterized by insular analy-ses—often defending and documenting earlier deci-sions—instead of contributing to a comprehensivedecision-making process. This pattern of response toNEPA, however, was characteristic of most federalagencies in that period, whether in transportation,land management, resource protection, or humanhealth and welfare programs.

By the early 1990s, leadership discussion, policyresearch, agency guidelines, practitioner peerexchanges, and project-level applications began torefocus on the sustainability intent of NEPA and onthe crosscutting, collaborative framework the legis-lation sought to develop. That framework was boththe major challenge and the necessary foundation foraddressing the Section 101 expectations for “pro-ductive harmony.”

Today, codified regulations and specific guidelinesfor NEPA compliance are in force for more than 100federal departments and independent agencies—including the U.S. Department of Transportation. Dif-ferent approaches and perspectives, however, areapplied to the priorities, needs, and concepts of envi-ronmental balance and sustainability, both in fulfillingtopical environmental process requirements, and inworking toward NEPA’s “balance umbrella,” whichimplies comprehensive, collateral harmony amongregulations and processes. Each agency has overseenprogress and successes in the application of NEPA inits nearly 40 years, but a new frontier is challengingtraditional agency roles and rules.

Assessing NEPAIn 1995, on the 25th anniversary of NEPA, the Pres-ident’s Council on Environmental Quality (CEQ)undertook a retrospective on the successes and short-comings of NEPA and provided some pertinent com-mentary on sustainability and practical applications:

Overall, what we found is that NEPA is a suc-cess—it has made agencies take a hard look at thepotential environmental consequences of theiractions, and it has brought the public into theagency decision-making process like no otherstatute. In a piece of legislation barely three pageslong, NEPA gave both a voice to the new national

consensus to protect and improve the environ-ment, and substance to the determination artic-ulated by many to work together to achieve thatgoal. To that end, NEPA charges CEQ and allfederal agencies with achieving “productive har-mony” among our environmental, economic,and social objectives. NEPA directs federal agen-cies to open their doors, bring the public in, andoffer genuine opportunities for participation andcollaboration in decision making. Despite thesesuccesses, however, NEPA’s implementation attimes has fallen short of its goals. For example,this NEPA effectiveness study finds that agen-cies may sometimes confuse the purpose ofNEPA. Some act as if the detailed statementcalled for in the statute is an end in itself, ratherthan a tool to enhance and improve decisionmaking. As a consequence, the exercise can beone of producing a document to no specific end.But NEPA is supposed to be about good decisionmaking—not endless documentation. (1)

CEQ specifically pointed out the link betweensustainability and societal aspirations:

Clearly, NEPA is much more than environmentalimpact statements and environmental assess-ments. It is an eloquent and inspiring declarationwhich, well before the term “sustainable develop-ment” became widely used, called for the integra-tion of our varied aspirations as a society. NEPA isa tool with tremendous potential to help buildcommunity and to strengthen our democracy. (1)

POINT OF VIEW presentsopinions of contributingauthors on transporta-tion issues. The viewsexpressed are not neces-sarily those of TRB orTR News. Readers areencouraged to commentin a letter to the editoron the issues and opin-ions presented.

Paving I-84 inManchester, Connecticut,1970s.

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Seeking SustainabilityEmbracing NEPA’s intent and opportunities for sus-tainability involves several principles:

� Apply the appropriate scale to actions andanalyses. In transportation projects, for example,this implies a perspective beyond the right-of-way.

� Give a front-and-center role to efficiencies,by any measure or category—energy, humanresources, money, timeline, or interjurisdictional orpolitical relations.

� Support sustainable decision making withalternatives developed through a broad, well-grounded thought process.

� In planning and NEPA analyses, aggressivelyadvance the spectrum of considerations involvingsustainable maintenance and operations.

� For integrated transportation, coordinatemultiple modes to address multiple transportationneeds and mandates for sustainability.

� Make stakeholder collaboration central, sothat agencies and institutions must expand beyondtheir traditional boundaries to provide guidanceand accountability.

Next Steps to SustainabilityProgrammatic SolutionsGreat progress has occurred on many of these frontsthrough interagency and multidisciplinary pro-grammatic agreements. Nationwide, 52 program-matic agreements are addressing various parts ofNEPA in various states, including categories ofendangered species, Section 106 (historic preser-vation), Section 4(f), land management, and docu-mentation procedures. But this is only the start ofwhat programmatic solutions can do or imply—the goal is broad consideration of agency and stake-holder issues and needs in sustainable balancewithout undue focus on project-specific details.

Cleaning the Attic: Simplifying Analyses Every attic needs a periodic cleaning out, includingNEPA’s. In some ways, specific, approved methodsin approach and analysis may impede a more com-plete consideration of sustainability. Complexanalyses of a single, high-profile issue may be miss-ing opportunities for simpler, more effective solu-tions for the long term that provide greater benefitin less visible categories of sustainability.

New Disciplines for Analysis The disciplinary approaches to NEPA need to keeppace with evolving technology or with policy andsocietal expectations for sustainability. The growinginventory of geocoded data and imagery, for exam-

ple, may provide for the next level of progress instreamlining the environmental review of projects.New disciplines not yet identified or defined will beneeded to integrate and translate the growingamount of primary data into program and projectdecisions under NEPA.

Sustainable BalanceHighly polished and well-reinforced traditionalagency perspectives are on notice in the next level ofsustainability under NEPA, whether the agency isfocused on transportation or resource protection. Theability to understand and place a mutually under-stood value on the elements of sustainable balance inany NEPA-based decision will become increasinglyimportant for cooperating agencies. These tenets aretaking hold in the multiagency Eco-Logical ecosys-tem-based approach to infrastructure.2

Visions for the FutureStrengthening Implementation of Section 101 An executive order should require each federalagency of the executive branch to adopt a compre-hensive, agencywide environmental policy, asdefined in Section 101 of NEPA. This would bestowa stronger and clearer mandate to the many effortslaunched under stewardship, sustainability, smartgrowth, context-sensitive solutions, placemaking,climate change, Eco-Logical, environmental man-agement systems, low-impact development, andother environmental initiatives. The executiveorder would pull the initiatives together, help man-agers make organizational and program adjust-ments efficiently, reduce the need for extensiveefforts to justify actions, and strengthen and syn-chronize efforts by the 50 states to meet the nation’senvironmental goals.

Reciprocal Consultation Federal agencies should revise their rules for regu-lating, planning, funding, or implementing their pro-grams to require formal consultation with thetransportation sectors of government. After 40 yearsof outreach efforts by the transportation sector,achieving full, reciprocal consultation among allagencies promises to save millions of dollars onwasted process, yielding enormous program imple-mentation benefits for the public.

For example, the Clean Water Act (CWA) rulesdo not require extensive public and agency consul-tation for sewer infrastructure planning. Althoughtransportation rules and policies require outreach onmatters involving impacts on water quality, wetlands

2 www.environment.fhwa.dot.gov/ecological/eco_index.asp.

Eco-Logical is amultiagency ecosystem-based approach toinfrastructure.

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protection, and other CWA issues, the CWA ruleshave no reciprocal mandate. Yet the availability ofsewer and water infrastructure often facilitates newdevelopment, and the new residents and neighborsthen need transportation relief. The joint planning ofinfrastructure would save money and improve qual-ity of life.

Clean the AtticA risk-based rationale should be applied to eliminatethose components of transportation impact analysisand project development that disproportionatelyconsume resources and time in relation to environ-mental risks, both human and natural. Over theyears, environmental impact analyses have steadilyaccrued information—the intentions are good, butno limits have been set. Although some progress hasbeen made through streamlining reviews, the timeand resources tied up in ineffective or inefficientprocesses are significant.

Programmatic SolutionsTransportation agencies and stakeholder agenciesshould review each other’s short- and long-rangeplans and programs regularly, to identify opportuni-ties for collaboration, cost sharing, and resourcebanking, to enhance program delivery and expandenvironmental benefits. Possible initiatives includestorm water mitigation banking, wildlife manage-ment programs, and recovery plans for threatenedand endangered species.

For example, the process for developing a stateimplementation plan–tribal implementation plan fortransportation conformity under the National Ambi-ent Air Quality Standards might serve as a model fora new programmatic process for environmental com-pliance in addressing stormwater impacts in water-sheds. Archaeological mitigation banking, driven byagreed-on research priorities, might free up projectsof low research interest from survey work and allowincreased focus on projects of high research interest.This would spend public resources on importantresearch questions and would streamline programdelivery.

Manage the DisciplinesStrategic oversight is needed to guide the growth oftransportation impact analysis and of new disciplinesfor efficient and effective decision making. Althoughpublic value is added when new tools, processes,and disciplines improve quality, save money, orstreamline results, the risk is that human and finan-cial resources may be spread too thin. Without astrategic vision, new processes can bog down and failto produce a public benefit.

Door-to-Door ApproachStovepipe programs for transportation infrastructuredevelopment—segmented into highway, road, bike,pedestrian, transit, paratransit, maritime ports, air-ports, and so on—should be replaced with a desti-nation and function approach, without strict regardto modal program responsibilities. Transportationservice improvement is no longer a modal process.A door-to-door approach can integrate and improveavailable means and choices of mobility to reach des-tinations. The approach can streamline NEPA pro-cessing by offering integrated, sustainabletransportation and mobility solutions, and by replac-ing the often perfunctory modal alternatives analy-sis required for NEPA, which a single sponsor agencymay not have full authority to deliver.

Beyond Our SphereTransportation decision makers will need to under-stand and account for things beyond the horizon butthat have a link to sustainability. Early seafaringexplorers could see only 14 miles to the horizonfrom the average ship, but things beyond their fieldof vision were clearly influential. Today, internationaltrade issues are increasing in importance, and a newera of space flight and transport is just beyond.

This brief list of future visions does not encompasssustainability in the context of NEPA but traces someinitiatives that could lead multiple agencies in a col-laborative direction with prospects for more effective,integrated, sensitive, and sustainable solutions.

Reference1. The National Environmental Policy Act: A Study of Its Effec-

tiveness After Twenty-Five Years. Council on Environmen-tal Quality, Executive Office of the President, WashingtonD.C., January 1997.

Edwards Branch inCharlotte, NorthCarolina, was restored as part of the EdwardsBranch WatershedImprovement Project.

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The authors are air qual-ity specialists with theFederal HighwayAdministration ResourceCenter; Houk is inDenver, Colorado, andClaggett in Santa Fe,New Mexico.

Solving the air pollution problems caused bytransportation, particularly from highways,has been a focus of U.S. policy makers fordecades. California introduced the first pol-

lution control requirements on new motor vehicles40 years ago. The federal government took legislativeaction via the Clean Air Act (CAA) and the NationalEnvironmental Policy Act, both introduced in 1970.Today, the Environmental Protection Agency (EPA)has the responsibility to set, review, and revise theNational Ambient Air Quality Standards (NAAQS).

Targeting PollutantsThe NAAQS focuses on six criteria pollutants: car-bon monoxide (CO), ozone, particulate matter (PM),nitrogen dioxide, sulfur dioxide, and lead. Highwaysources contribute significantly to emissions of CO,the precursors of ozone, and PM; the other pollutantsderive primarily from industrial sources.

Since the introduction of air quality standards,the United States has reduced the levels of criteria

pollutants (Figure 1). Between 1980 and 2006, aggre-gate emissions of the criteria pollutants havedecreased by 49 percent, despite an increase of 121percent in the gross domestic product; of 101 percentin vehicle miles of travel (VMT); of 32 percent inpopulation; and of 29 percent in energy consumption(1). Nevertheless, ground-level concentrations ofozone and fine PM continue to provide challenges inmany areas of the country—in 2000, more than 100million people were living in counties that exceededthe NAAQS limits for these pollutants (1).

Concerns about climate change have increasedattention on the greenhouse gas (GHG) emissionsfrom the transportation sector. Transportation is thelargest source of carbon dioxide (CO2) emissions inthe United States and is the second-largest source ofall GHG emissions combined (2). The U.S. highwaysystem is the world’s fourth largest emitter of CO2,after China, Russia, and the rest of the United States(3).

In the past decade, transportation air quality activ-ities have focused on mobile source air toxics(MSATs), which have adverse health effects but are notsubject to ambient air quality standards. MSATs ofparticular concern are benzene, a carcinogen; 1,3-butadiene; and diesel PM. In addition, EPA has iden-tified dozens of other chemicals that are emitted bymotor vehicles and that can lead to adverse healthimpacts.

Air Quality ManagementSuccesses and Emerging Challenges

JEFFREY HOUK AND MICHAEL CLAGGETT

Smog in Atlanta, Georgia.

FIGURE 1 Comparison of criteria pollutant levels to theNational Ambient Air Quality Standards (1). Nationallevels are shown, which are averaged across all siteswith complete data for the time period.

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Air Quality SuccessesCO AttainmentIn 1990, EPA designated nearly 90 communities innonattainment of the ambient air quality standard forCO; today only 3 remain in nonattainment. Since1990, EPA has observed a decreasing trend in COemissions nationwide (1); from 1990 to 2006, thesecond maximum 8-hour average concentrations ofCO decreased by 62 percent. Transportation remainsby far the largest source of CO emissions, but thedecrease was attributable in part to technologicaladvances, namely the catalytic converter and oxy-genated fuels.

Emissions Reduction TechnologyIn the past 30 years, drastic changes have occurredin emissions reduction technology. Computer-con-trolled fuel injection systems have replaced the car-buretor; catalytic converters and evaporativeemissions control systems are commonplace; andon-board diagnostic computers monitor the fuel andemissions control systems and notify the driver ofany problems.

In addition, new materials—including high-strength steels, ceramics, and carbon fiber—havereduced vehicle weight and fuel consumption.Hybrid-electric drivetrains are available on severalvehicle models, and advanced electric drive tech-nologies, including fuel cells, plug-in hybrid vehi-cles, and all-electric vehicles powered by lithiumbatteries, are being tested on the road. New fuels,such as biodiesel and cellulosic ethanol, are startingto reduce the carbon footprint of the fuel supply,improving U.S. energy security at the same time byreducing dependence on imported oil.

Transportation ConformityThe CAA requires that transportation planning con-form to the goals set in air quality planning. Long-range transportation plans therefore cannot generateemissions that exceed the targets set in air qualityimprovement plans. This conformity requirementhas led to better coordination between air qualityand transportation planners, improvements in traveland air quality modeling, and better-informed deci-sion making.

Congestion Mitigation and Air QualityThe Congestion Mitigation and Air Quality (CMAQ)Improvement Program provides funds to trans-portation agencies for projects that reduce criteria airpollutants from transportation-related sources. Thelegislation requires agencies distributing CMAQfunds to give priority to diesel engine retrofits and toother cost-effective emissions reduction and conges-

tion mitigation activities that provide air quality ben-efits. A 2002 review of CMAQ by a National ResearchCouncil–appointed committee found that the pro-gram had been successful in achieving its intendedobjectives, but that improvements could be made inquantifying the benefits from projects (4).

Emissions ModelingModels have been developed to quantify the differ-ences in air quality emissions from changes in travelactivity. Advances in urban travel demand modelinghave helped planners simulate real-world travelactivity. For instance, EPA’s MOBILE6.2 emissionsmodel has improved the characterization of vehicleemissions under different conditions, and EPA’sMOVES model promises additional improvements.

New measurement technologies have improvedthe scientific understanding of emissions under vari-ous conditions and have improved emissions esti-mates. For example, portable emissions monitoringsystems can measure tailpipe emissions as a vehicledrives down the road. Other research includesadvanced traffic counts, speed studies, and instru-mented vehicle studies to characterize vehicle activity.

Future ChallengesThirty years of research and experience haveimproved understanding of transportation-relatedair pollution, but new issues require attention. Fol-lowing are some of the key air quality challenges fac-ing the transportation community in the next decadeand beyond.

Tighter Air Quality StandardsEPA periodically revisits each of the criteria pollutantair quality standards and makes adjustments as nec-essary. In the past 3 years, EPA has tightened thestandards for ozone and PM. As a result, more areasare or will be in nonattainment.

These nonattainment areas will need to identifynew control strategies to reduce emissions and com-ply with the standards. Some of these areas are hav-ing to comply with the CAA transportationconformity requirements for the first time, and localofficials will need to understand the regulatory

Portland GeneralElectric’s chargingstations support bothplug-in electric and plug-in hybrid vehicles, a stepin reducing vehicleemissions.

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requirements and the necessary modeling tools.Another problem is reconciling the trade-offs whenmitigation strategies reduce the emissions of one pol-lutant but increase the emissions of another.

PM Hotspot AnalysisFor a long time, EPA has been concerned that PMhotspots—that is, areas of elevated PM concentra-tions—may develop in the vicinity of highway andtransit projects. A lack of adequate modeling tools,however, has delayed the quantitative analysis ofpotential PM hotspots; improved models areexpected to be available soon, and agencies will berequired to calculate the PM concentrations nearproposed projects. Departments of transportationnationwide will need to develop expertise in the toolsfor performing this analysis.

MSATs and Roadside Health IssuesEpidemiological studies of occupational exposure tohigh concentrations of some MSAT compounds havedocumented adverse human health effects, includingcancer and irritation of the respiratory tract. Recentroadside epidemiological studies also have raisedhealth issues; some report that proximity to roadwaysis related to adverse health outcomes, particularly res-piratory problems. As a result, government agenciesare concerned about public exposure to MSATs.

The policies applied to MSATs and to other road-side health issues—as well as those crafted to dealwith criteria air pollutants—have significant gaps,however. In 2001 and 2007, EPA issued rules to con-trol MSATs through motor vehicle emission and fuelstandards, and FHWA released guidance for gaugingthe potential impacts of proposed highway projects.But other strategies adopted for criteria pollutants donot apply to MSATs, including the clean air goals orcriteria set by the NAAQS, the transportation con-formity process, and the CMAQ program.

The Health Effects Institute (HEI) has completedobjective reviews of the health issues that result fromexposure to MSATs (6, 7). The findings show that

exposure to many MSATs comes from sources otherthan vehicles. HEI concluded that the data in mostcases are insufficient for assessing the effects of ambi-ent concentrations on human health; for example,considerable uncertainty remains about the lowestconcentration associated with adverse health effectsfrom benzene exposures. No national consensus hasbeen reached on acceptable levels of MSAT exposure.

Congestion Implications As travel activity grows and new infrastructure doesnot keep pace, congestion has increased on urbanand rural roadways. Congestion has implications notonly for air quality, because vehicle emission rates aregenerally higher under congested conditions, butalso for energy consumption and GHGs, becausevehicles are less efficient under congested condi-tions. If congestion is not addressed and the trendscontinue, fulfilling air quality goals and climatechange goals will be more difficult.

Improving Emissions Models New air quality challenges have led to the need forbetter models. The transportation community needsbetter tools to assess the finer-scale impacts of proj-ects on PM and MSATs. Better local-scale tools wouldimprove understanding of the energy consumptionand GHG impacts of projects, as well as of the travelactivity impacts of smart growth projects.

In 2009 and 2010, transportation agencies willneed to develop expertise in EPA’s MOVES model,which will replace the MOBILE model used since the1970s. The differences in emissions estimatesbetween MOVES and California’s Emfac model alsowill need to be reconciled.

Better integration of transportation models andair quality models will help planning agencies meetthe growing demands of transportation and air qual-ity analyses. Also needed are better projections offuture VMT growth, including a better understand-ing of the effects on VMT from increased fuel pricesand from changes in demographic trends.

Mean concentrations ofparticulate matter (PM) withdiameters ≤ 2.5 �m during anentire modeling period (a)predicted by the aerosol opticaldepth (AOD) model and (b) bythe non-AOD model. Starsrepresent the U.S. EPAmonitoring sites.

(a) (b)

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Addressing Climate ChangeSignificant steps have been taken to reduce GHGemissions from the transportation sector and to pre-pare areas for the possible future impacts of climatechange. Examples include the aggressive fuel econ-omy standards and renewable fuels program of the2007 Energy Independence and Security Act (5), andvoluntary programs to reduce transportation GHGemissions, such as the SmartWay Transport programto reduce emissions from hauling freight.

The United States is also a hub of climateresearch. In March 2008, the Transportation ResearchBoard, working with the National Research Council’sBoard on Earth and Life Studies, published a specialreport on the potential impacts of climate change ontransportation (8); and FHWA issued a study on theeffects of potential climate changes on the highwayinfrastructure of the Gulf Coast—the first-everattempt to quantify mode-specific climate impacts ina specific region of the United States (9).

More than 30 states have adopted climate actionplans. Most of these include actions to reduce trans-portation GHG emissions through cleaner vehiclesand renewable fuels, through increased public tran-sit, and through the implementation of smart growthstrategies to reduce growth in VMT. About half of theplans include requirements to analyze the potentialGHG emission impacts of transportation plans orindividual projects.

Climate change raises two challenges for trans-portation:

� Mitigation, reducing GHG emissions; and � Adaptation, preparing for the impacts of cli-

mate change on transportation infrastructure.

On the mitigation side, major reductions areneeded in transportation GHG emissions to achievethe levels that scientists have determined are neces-sary to avoid the worst impacts of climate change.The new programs in the 2007 energy bill will haltthe increase of transportation-related GHG emissionsbut do not provide substantial reductions.

Addressing transportation GHG emissions requiresa comprehensive suite of measures, including morefuel-efficient vehicles, cleaner fuels, smarter develop-ment to reduce per capita VMT, increased public tran-sit, and carbon sequestration. Many of these activitieswill yield additional benefits, such as reduced urbanair pollution and greater energy security.

Adaptation poses a significant challenge becauseof the uncertainty about the timing and magnitudeof climate impacts. Transportation agencies routinelymake investment decisions for infrastructure thatwill last many decades, and decisions made today can

help prevent costly impacts in the future. Tools areneeded to help planning agencies factor climate vul-nerability and risk into the decision-making process.Although much work is under way, the 2008 TRBand FHWA reports offer valuable advice to helpagencies get started.

Applying the FrameworkThe study of transportation’s impacts on air qualityhas increased in complexity in the past three decades.Despite many successes, new challenges have arisen.

A comprehensive policy framework, establishedto control the criteria air pollutants, was a majorcontributor to many of the successes. Can this sameframework be applied or adapted to meet the newchallenges? Dedicated professionals in the field, withbroad expertise and experience, will continue towork to improve air quality through research, inno-vation, and implementation of strategies to reduceemissions.

References1. Latest Findings on National Air Quality. EPA-454/R-07-007.

Office of Air Quality Planning and Standards, U.S. Envi-ronmental Protection Agency, January 2008.

2. Inventory of U.S. Greenhouse Gas Emissions and Sinks:1990–2006. EPA-430-R-08-005, U.S. Environmental Pro-tection Agency, April 2008.

3. FHWA staff analysis using data from International EnergyOutlook 2008. Report DOE/EIA-0484, Energy InformationAdministration, June 2008.

4. Special Report 264: The CMAQ Program: Assessing 10 Yearsof Experience. Transportation Research Board of theNational Academies, Washington, D.C., 2002.

5. Public Law No. 110-140, December 19, 2007.6. Health Effects Institute. Diesel Emissions and Lung Cancer:

Epidemiology and Quantitative Risk Assessment. A SpecialReport of the Institute’s Diesel Epidemiology Expert Panel,Boston, Massachusetts, June 1999. www.healtheffects.org.

7. Health Effects Institute. Mobile-Source Air Toxics: A Criti-cal Review of the Literature on Exposure and Health Effects.Special Report 16, HEI Air Toxics Review Panel, Boston,Massachusetts, November 2007, www.healtheffects.org.

8. TRB Special Report 290: Potential Impacts of Climate Changeon U.S. Transportation. National Research Council of theNational Academies, Washington, D.C., March 2008.

9. Impacts of Climate Change and Variability on TransportationSystems and Infrastructure: Gulf Coast Study, Phase I. Syn-thesis and Assessment Product 4.7, U.S. Climate ChangeScience Program, Washington, D.C., March 2008.www.climatescience.gov/.

Vehicle in the SmartWayTransport Partnership, aninnovative collaborationbetween the U.S.Environmental ProtectionAgency and the freightindustry to increaseenergy efficiency whilereducing greenhousegases and air pollution.

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Cramer is a ResearchAssistant Professor atUtah State Universityand a researcher with theUtah TransportationCenter, Utah StateUniversity, Logan.Bissonette is leader of theU.S. Geological SurveyCooperative Fish andWildlife Research Unit,Utah State University,and Professor in theDepartment of WildlandResources.

Transportation ecology is a newly devel-oped science that focuses on the interac-tions of organisms and the environmentwith transportation infrastructures and

vehicles (1). A major goal is to understand the effectsof roads on wildlife populations and the effectivenessof measures to assist wildlife over and under roads—to prevent collisions with vehicles and to helpwildlife move across the natural landscape.

The practices and science to accommodatewildlife along transportation corridors aim to main-tain safety and ecological integrity. In the past, trans-portation systems often were built with little regardfor the need of wildlife to move. As wildlife–vehiclecollisions with large animals, such as deer andmoose, became more of a problem, the safety issuesof wildlife on the road began to be addressed, mainlyby fencing roads and installing wildlife crossings.

As the ecological effects of roads on wildlife andfish populations and on ecological processes such aswater movement were identified, additional mitiga-tion measures were developed to help wildlife, fish,

and water move under and over roadways. Withimproved understanding of these effects—and of thecost and efforts to mitigate these effects—planningfor ecological systems and their inhabitants isbecoming part of long-range planning for trans-portation, to avoid, minimize, and reduce the costsinstead of waiting until later on in the project stage.

Most states have begun accommodating wildlifeand fish along transportation corridors, with hun-dreds of terrestrial crossings and thousands of aquaticcrossings. The ecological and safety reasons are clear,and trends are emerging in the mitigation of the effectsof roads on wildlife across North America.

Safety ConcernsSafety is the most important wildlife-related concernfor transportation agencies, but more than everbefore, transportation planning and projects are tak-ing into account the ecological effects of roads andvehicles on multiple species. More than 1.5 millionwildlife–vehicle collisions occur annually in theUnited States (2).

Many of these collisions cause human deaths. In2008, the Highway Loss Data Institute reported that

Transportation Ecology and Wildlife PassagesThe State of the Practice and Science of Making Roads Better for Wildlife

PATRICIA C. CRAMER AND JOHN A. BISSONETTE

A wildlife overpass allowsthese does to cross I-15(not visible) in SouthernUtah.

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Deer graze near a roadway in Utah. The practicesand science to accommodate wildlife alongtransportation corridors aim to maintain safety andecological integrity.

THE ENVIRONMENT AND TRANSPORTATION Making Both Better Than Before

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the number of fatalities from wildlife–vehicle colli-sions has more than doubled in the past 15 years,with 223 people killed in 2007. In addition to humandeaths and injuries, other costs are associated withthese accidents. In a study of deer–vehicle collisioncosts in Utah from 1996 to 2001, Kassar found thatthe average cost for vehicle damage, lost lives, deerlost values, and human injury from a single accidentwas $3,470 (3). This conservative estimate wouldplace wildlife–vehicle collision costs nationwide atmore than $5.2 billion annually. Others estimate thecost as closer to $8.3 billion (4).

These averages also can be used to evaluate thecost-effectiveness of mitigation measures. For exam-ple, a wildlife crossing that costs $1 million wouldpay for itself over the service life of the structure if itprevented 180 to 288 collisions with wildlife—depending on the cost estimates used.

Transportation ecologists are only beginning tounderstand the many costs of vehicle collisions androad effects on populations of animals and ecosys-tems. According to averages calculated in one study,1 million vertebrates are killed each day on U.S.roads (5).

Preserving PopulationsMany ecologists are concerned about animal popu-lations and their ability to exist in the presence ofroads. If a population cannot sustain its numbersbecause of high rates of road-related mortalities orbecause of impediments to movement, the speciesmay face local extinction.

An example is the Florida panther, a highly endan-gered species. In 2007, at least 15 panthers were killedon Florida roads. The population of 80 to 100 animalscannot compensate for this road mortality.

Gibbs and Steen found a higher percentage of maleto female turtles in wetlands near roads than in wet-lands at a distance from roads, because of the mortal-

ity associated with the females moving across or nearroads to nest upland (6). Another study discoveredsigns of genetic isolation among bighorn sheep pop-ulations in southeastern California mountain rangesthat were bisected by Interstate highways (7).

Data-based research results such as these offerinsights into how roads and traffic affect wildlife andcan assist in developing mitigation measures forroads and ways to avoid building new roads in eco-logically sensitive areas. Efforts to mitigate and avoidhave grown exponentially in the past four decades(8) as transportation agencies have become moreconcerned about wildlife and about potential meth-ods for mitigation.

Initiatives and Approaches As concerns rise for all species affected by roads, ini-tiatives and legislative actions are directing trans-portation agencies to consider during the planningprocesses the needs that terrestrial and aquatic specieshave for ecological connectivity. For example, underWashington State law, culverts that block the passageof salmon must be identified and replaced, whetheras part of a transportation project or as a stand-aloneproject. A 2007 Washington State Department ofTransportation (DOT) Executive Order directsregional and statewide long-range transportationplans to identify potentially affected fish and wildlifehabitats as early as possible during planning and toseek opportunities to restore habitat connectivityalready damaged by transportation corridors.

The Vermont Agency of Transportation and theVermont Fish and Wildlife Agency have signed amemorandum of agreement to work together toimprove the accommodation of wildlife and aquaticorganism movement around and through trans-portation systems and to minimize habitat fragmen-

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This Florida panther, a highly endangeredspecies, uses a wildlifecrossing near Big Cypress, Florida.

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Wildlife crossing over roads can pose danger toanimals and motorists. In 2008, the Highway LossData Institute reported that the number of fatalitiesfrom wildlife–vehicle collisions has more thandoubled in the past 15 years.

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tation caused by transportation infrastructure.In 2008, the Western Governors’ Association

(WGA), representing 19 states, adopted the WildlifeCorridors Initiative. The WGA Transportation Work-ing Group developed policy recommendations forthe initiative that would prioritize the preservation ofwildlife corridors and crucial habitat in transporta-tion planning, design, and construction.

At the national level, Section 6001 of the Safe,

Accountable, Flexible, Efficient TransportationEquity Act: A Legacy for Users (2005) instructstransportation agencies in long-range transportationplanning development to consult with state, tribal,and local agencies responsible for land use manage-ment, natural resources, environmental protection,and conservation. The agencies must compare thetransportation plans with the other groups’ plans ormaps, to evaluate potential impacts. The long-range

Approximately 300,000 collisions between cars and largeanimals—mostly deer—are reported each year on U.S.

highways, and the number is increasing by about 6,700 peryear. Insurance industry data and carcass tallies, however, indi-cate that the actual number of wildlife–vehicle collisions(WVCs) with large animals is 1 to 2 million per year. These col-lisions cost society $8 billion annually.

The U.S. Congress directed the Secretary of Transportation toconduct a national study of WVCs, detailing the causes, impacts,and potential solutions. The report to Congress was submittedin November 2007, and the Federal Highway Administration isto publish the report. FHWA recently released a manual withtechnical guidance on measures that are considered best prac-tices.

WVC Characteristics and ThreatsCompared with other crash types, collisions with wildlife

� Occur most often on two-lane, low-volume roadways;� Are more likely to be on straight, dry roads;� Happen more frequently in areas with large wildlife pop-

ulations;� Cause less severe crashes—except when the collisions

involve either moose or motorcycles;

� Occur where roadways cross drainages;� Are mostly single-vehicle crashes;� Occur more often during early morning and evening

hours;� Occur more frequently during the fall and spring months;

and� Show less of a peak for younger and older drivers.

Road mortality is a substantial concern in the conservationof some species. The report identifies 21 threatened and endan-gered species for which road mortality is among the majorthreats to survival in the United States:

� Mammals: Lower Keys marsh rabbit, Key deer, bighornsheep (peninsular California), San Joaquin kit fox, Canada lynx,ocelot, Florida panther, red wolf.

� Reptiles: American crocodile, desert tortoise, gopher tor-toise, Alabama red-bellied turtle, bog turtle, copperbellywater snake, eastern indigo snake.

� Amphibians: California tiger salamander, flatwoods sala-mander, Houston toad.

� Birds: Audubon’s crested caracara, Hawaiian goose,Florida scrub jay.

Best Practices for Reducing Wildlife–Vehicle Collisions

P A T R I C K T . M C G O W E N A N D M A R C E L P . H U I J S E R

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350,000

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Cs

FIGURE 1 Number of wildlife–vehicle collisions (WVCs), 1990–2004.

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Several species threatened and endangered by road traffic (left toright): Bighorn sheep, San Joaquin kit fox, American crocodile, bogturtle, and Hawaiian goose.

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Many more species are affected by other impacts of road-ways, such as loss, reduction in habitat quality, or fragmenta-tion of habitat.

Expert Panel RecommendationsTo identify measures to reduce the numbers of animal–vehiclecollisions, an expert panel was formed with representativesfrom resource agencies, state departments of transportation,nongovernment organizations, and universities from across thecountry. The panel received a draft of the report to Congressand categorized the effectiveness of more than 30 measures forreducing WVCs with large animals.

According to the panel, measures that should be imple-mented include the following:

� Wildlife fencing,� Wildlife underpasses and overpasses with fencing, and� Public information and education.

Although uncertain that public information would reducecrashes, the panel was convinced that public information andeducation were good practice.

Measures that should be researched further include the fol-lowing:

� Reducing speed by traffic calming measures, reducing theposted speed limit, or reducing the design speed;

� Installing warning signs that are larger, nonstandard, sea-sonal, or triggered by animal detection;

� Developing in-vehicle devices to warn drivers about ani-mals on the roadside;

� Improving visibility through lighting or by removing veg-etation;

� Avoiding vegetation or deicing alternatives that mayattract animals to the roadway;

� Reducing population size through culling or habitatalteration;

� Keeping animals off the roadway with boulder barriers,long tunnels and bridges, or overpasses and underpasses with-out fencing;

� Reducing traffic volume;� Using crossing guards to stop traffic for wildlife;� Installing wider, more reflective white stripes; and� Expanding the median.

The panel recommended that the following measures shouldneither be implemented nor researched further:

� Warning the driver with standard wildlife warning signsor with reflective collars on wildlife;

� Warning animals or keeping them off the road with suchdevices as reflectors and mirrors, audio signals in the right-of-way, deer whistles on vehicles, scent repellents, hazing, inter-cept feeding, or deer flagging models;

� Attempting to reduce the wildlife population throughrelocation or antifertility treatments; and

� Scheduling seasonal road closures.

Mitigation only at known locations of frequent animal cross-ings may not reduce WVCs significantly—the approach must becomprehensive. Good data are needed to identify and prioritizethe mitigation locations. The problem must be considered in thecontext of the landscape and with an understanding of the tar-get species. Principles that minimize the potential for WVCsshould be incorporated into alignment selection and roaddesign. The measures that are implemented should be moni-tored, evaluated, and published.

McGowen is Assistant Professor, Western TransportationInstitute and the Civil Engineering Department, MontanaState University, Bozeman; and Huijser is a Research Ecologist,Western Transportation Institute.

FIGURE 2 Total approach to reducing WVCs.

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T Culvert replacements areopportunities fortransportation plannersand wildlife ecologists toaccommodate wildlifemovement. Pictured (left)is an Idaho culvert beforeand (right) afterrehabilitation.

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plans must include a discussion of potential envi-ronmental mitigation activities with the greatestpotential to restore and maintain environmentalfunctions affected by the plan.

The federal natural resources agencies and the Fed-eral Highway Administration have developed Eco-Log-ical: An Ecosystem Approach to DevelopingInfrastructure Projects, which helps agencies worktogether over the long term to protect naturalresources, to mitigate harmful effects, and to ensurethat mitigation agreements are kept.1 The approach isevolving to assist in larger-scale spatial and temporalanalyses of transportation effects on ecological com-munities and in actions that can minimize these effects.1 www.environment.fhwa.dot.gov/ecological/eco_index.asp.

A moose makes use of awildlife crossing at US-89in Utah. Several statesand provinces have builtmultiple wildlifepassages for a range ofspecies.

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Many of the estimated 1.4 million road–stream crossingsthroughout the United States use culverts for water to

pass underneath the roadway. Culverts, however, can createbarriers to the upstream movement of aquatic species and, insome cases, to the downstream movement. Many differentmethods are used to assess whether a culvert crossing is a bar-rier. Varieties of barriers include the following:

� A total barrier, which allows no movement;� A partial barrier, which allows only some species or life

stages within a species to move; and� A temporal barrier, which allows movement at only some

flow rates.

Different techniques can yield different assessments. One tech-nique may identify a structure as passable, yet another may iden-tify the same structure as a barrier. The goal is for a culvert toprovide the free passage of all aquatic species in the stream forall flows.

Identifying BarriersTotal barriers are easy to iden-tify. Culverts that have largedrop-heights at the down-stream outlet will limitseverely—or prevent—theupstream movement of manyfish species; at some height, allspecies will be blocked—

including good leapers like troutand salmon. The U.S. Forest Servicein Montana has established 6 feetas the leap height threshold forrainbow trout.

Another type of total barrieroccurs in medium- to high-gradi-ent streams. Without baffling sys-tems or natural substrate bottoms,culverts at steep slopes will gener-ate fast flows. The velocity ofwater can become too fast foraquatic species to swim or crawlagainst without exhaustion. Incontrast, road crossings that mimicnatural stream channel conditionsor that have properly designedand constructed baffling systemsto slow the water down and toprovide resting areas are easy toidentify as passable. Culvertsbetween these extremes are diffi-cult to assess.

Contributing to the difficultyare the changing flow conditionsin the stream and the crossing. An assessment at low-flow con-ditions may find the crossing passable; however, as the flow rateincreases, the velocity of the water may reach a point at which it

Assessing Road Barriers to Aquatic Species

Lessons Learned in the Northwest

M A T T H E W D . B L A N K

This culvert in western Montanaserves as a leap barrier toresident fish species.

A concrete box culvert in amedium- to high-gradientmountain stream. The culvertwidth is less than the width ofthe stream channel; therefore,during high flows, as shown inthe photo, the constrictioncreates a velocity barrier tothe upstream passage of mostfish species. Because the watervelocities also create scouringdownstream, the culvertincludes an outlet drop, whichfish must negotiate inaddition to the watervelocities within the structure.

The author is Assistant Research Professor, WesternTransportation Institute and Department of Civil Engineering,Montana State University, Bozeman.

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Multispecies CrossingsWildlife crossings—which help wildlife move overand under roads—have been constructed in NorthAmerica since 1973, when Colorado installed thefirst underpass for wildlife under Interstate 70 nearVail Pass. More than 700 terrestrial and thousands ofaquatic passages accommodate wildlife in the UnitedStates and Canada (9).

A review of 26 studies examining the effectivenessof 76 crossings revealed that all of the crossingspassed wildlife, and that 74 passed the target species(Cramer, unpublished data). Many crossings initiallywere built for a single target species, chiefly deer. Inthe 1980s, Florida DOT built 38 wildlife passagesunder Interstate 75 in Southern Florida, primarily for

A bighorn sheep crossesUS-93 in Arizona using anunderpass.

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limits or prevents passage. During high-water periods, excessivewater depth, high velocities, moving bedload, and debris cancreate conditions that are unsafe for measurements and thatprevent the use of many assessment techniques.

Regional ScreeningOne approach to performing quality assessments of a large num-ber of culverts is to develop a regional screening tool. The toolwould apply physical parameters such as culvert length, slope,and outlet drop height—combined with information about thelocomotive abilities of the aquatic species within the stream—toseparate the culverts into total barriers, passable barriers, andundetermined. Structures that cannot be assessed can begrouped by physical, geomorphic, hydrologic, and biologicalattributes.

More detailed assessments can be performed on a subsetwithin each group, using a direct measure of passage. Passiveintegrated transponder—or PIT—tags placed inside representa-tive individuals of the aquatic species of interest are effective asa direct measure of passage, even during high-water periods;detection antennae are installed on the upstream and down-stream ends of the structure. The technique is time-consumingand labor- and equipment-intensive; nonetheless, natural move-ments can be monitored in relation to a range of flow conditions.

Results from the direct assessments can be used to determineor refine regional thresholds for structures within each groupfor various species and life stages. Passage can be inferred forstructures that were not directly assessed. Thresholds that aredefined and refined for a region should be published andpooled nationally.

Comprehensive and PracticalAn assessment should consider all potential barriers—includingirrigation diversions and dams—on a watershed scale. Entitiesbeyond the transportation agencies should be involved, becausethe solutions to aquatic connectivity are the shared responsibil-ity of all landowners, public and private. Restoring passage at asingle crossing may expand the range of an already isolated pop-

ulation only marginally if other barriers remain upstream ordownstream. Assessing a structure or all structures for all aquaticspecies that live within the watershed may not be practical; iden-tifying a priority species may be necessary.

After assessments are complete, and the decision is made toreplace or retrofit a structure, design can begin. Many statedepartments of transportation, such as Maine and Washington,as well as the Federal Highway Administration, have prepareddesign guides for fish passage at newly constructed and at retro-fitted crossings.a

In general, an assessment should be as accurate as possible—a culvert that is limiting passage should be identified as a prob-lem. Many aquatic species in U.S. streams and rivers face dauntingchallenges for long-term survival and depend on connected habi-tats. Making the nation’s road crossings passable for these speciesis important and can be achieved with proper assessment, deci-sion making, design, and construction.

a For more information about Hydraulic Engineering Circular 26:Fish Passage at Bridges and Culverts, see www.fishpassage.wsu.edu/.

Direct ApproachMonitor movement directlywith a field experiment that

measures aquatic speciesmovement and compares the

movement timing to flowconditions in a structure.

• Tagging studies: mark-recap-ture, PIT tagging, or others(e.g., radio telemetry)

• Visual observations• Video camera

• Regional screen based on field and laboratory experiments that establishthresholds such as maximum outletdrop height, maximum culvert slope,or slope by length

• Hydraulic modeling synthesized withlocomotive abilities of aquatic species

• Comparisons between upstream anddownstream population characteris-tics

• Genetic differences

Indirect ApproachApproximate movement potential

using thresholds, hydraulic modeling,or comparisons between populationcharacteristics measured upstream

and downstream of a structure.

FIGURE 1 Direct and indirect approaches to assessments of culverts.

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the Florida panther but also for all other species inthe area. This was the first set of multiple passages formultiple species.

Passing many species with different movementabilities helps to promote permeability, the ability ofa variety of wildlife to move across a landscape in thecourse of daily activities and during dispersal move-ments. To create a series of wildlife passages thatprovide permeability for multiple species is a goal ofmany transportation ecologists.

Several states and provinces have built multiplewildlife passages for a range of species. Whenever theTrans-Canada Highway is widened in its stretchthrough Banff National Park in Alberta, Canada—orto the east or west of the park—wildlife underpassesand overpasses are built. Multiple species of mam-mals from grizzly bear to pine marten traverse the 24-plus passages; researchers have documented morethan 100,000 wildlife crossings in the past twodecades (10, 11).

US-93 in Montana incorporates more than 55wildlife passages, with another 20 or more planned.Remote trail cameras have revealed many speciesusing these passages, including puma, white-tailedand mule deer, black bear, porcupine, great hornedowl, and others. A series of three extended bridgesalong US-7 in Vermont—known as the BenningtonBypass—has proved effective in passing multiple

wildlife species, from white-tailed deer and bobcatsto small mammals. Future projects to create multi-ple passages for wildlife include Washington State’sI-90 project, with 17 wildlife passages; and Col-orado’s I-70 passages, which will offer an overpass forwildlife.

Key OpportunitiesMost wildlife crossings are created in conjunctionwith highway upgrades. Lane additions, bridge andculvert replacements, and other road improvementsare key opportunities for transportation planners andwildlife ecologists to find ways to accommodatewildlife movement.

Stream flow is a major consideration when agingculverts are replaced. During these replacements, fillcan be removed and a bridge installed to allowwildlife movement, especially along the riparian cor-ridors, which are natural movement pathways forterrestrial and aquatic wildlife.

Culverts can be enlarged to allow for terrestrialmovement along the sides of a stream. Theseupgrades allow terrestrial wildlife and anglers to passunder the road without having to negotiate water orlarge rocks that may be placed for rip rap. If plannedcorrectly, these enlargements also facilitate more nat-ural hydrologic flow, and can assist with storm waterrunoff, an important feature in preparation for hydro-

Mitigation measures suchas culverts help fish, likethis steelhead, moveunder roadways.

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logic changes associated with climate change.Terrestrial structures can be retrofit or upgraded

for wildlife permeability. For example, New MexicoDOT is improving wildlife structures along Inter-state 40 and State Highway 333 in Tijeras Canyon. Tomake the roads more permeable for wildlife, NewMexico DOT is retrofitting a bridge underpass bywidening a shoulder for wildlife pathways; clearingbrush near three bridges to give deer and other preybetter visual clearance; and installing wildlife-prooffences, as well as escape ramps and at-grade wildlifecrossings with motorist warning systems.

Guidance and ToolsWhen designing new and upgraded transportationinfrastructure, state and provincial transportationagencies are increasing their efforts to find thousandsof opportunities to accommodate the needs forwildlife, fish, and ecological processes to move. Withmore than 6.4 million kilometers of roads in theUnited States (1), the opportunities are ample. States,provinces, and local entities are also finding that ear-lier consideration of wildlife and ecological needs intransportation planning offers more opportunities toavoid and minimize potential project impacts well inadvance of the need for mitigation, saving time andmoney.

As these practices spread and the science devel-ops, reports and tools are becoming available forplanners and practitioners. For example, a recentNational Cooperative Highway Research Program(NCHRP) project, Evaluating the Use and Effective-ness of Wildlife Crossings,2 developed a website thatincludes a decision tool to assist road planners, engi-neers, and wildlife ecologists in mitigating roads forwildlife.3 The tool is also available on the website ofthe American Association of State Highway andTransportation Officials’ Center for EnvironmentalExcellence.4 In addition, the International Confer-ence on Ecology and Transportation holds biennialmeetings and publishes all papers presented.5

References1. Forman, R. T., D. Sperling, J. A. Bissonette, A. P. Clevenger,

C. D. Cutshall, V. H. Dale, L. Fahrig, R. France, C. R. Gold-man, K. Heanue, J. A. Jones, F. J. Swanson, T. Turrentine,and T. C. Winter. Road Ecology: Science and Solutions.Island Press, Washington, D.C., 2003.

2. Hedlund, J. H., P. D. Curtis, G. Curtis, and A. F. Williams.Methods to Reduce Traffic Crashing Involving Deer: What

Works and What Does Not. Insurance Institute for HighwaySafety, Arlington, Virginia, 2003.

3. Bissonette, J., C. Kassar, and L. J. Cook. Assessment ofCosts Associated with Deer–Vehicle Collisions, HumanDeath and Injury, Vehicle Damage, and Deer Loss. HumanWildlife Conflicts, 2(1):17–27, 2008.

4. Huijser, M., P. McGowen, J. Fuller, A. Hardy, A. Kociolek,A. Clevenger, D. Smith, and R. Ament. Wildlife–VehicleCollision Reduction Study. Report to Congress, FederalHighway Administration, U.S. Department of Transporta-tion, Washington, D.C., 2007.

5. Lalo, J. The Problem of Roadkill. American Forests, Sep-tember–October 1987, pp. 50–52.

6. Gibbs, J. P., and D. A. Steen. Trends in Sex Ratios of Turtlesin the United States: Implications of Road Mortality. Con-servation Biology, 19:552–556, 2005.

7. Epps, C. W., P. J. Palsboll, J. D. Wehausen, G. K. Roderick,R. R. Ramey III, and D. R. McCullough. Highways BlockGene Flow and Cause Rapid Decline in Genetic Diversityof Desert Bighorn Sheep. Ecology Letters, 8:1029–1038,2005.

8. Bissonette, J. A., and P. C. Cramer. NCHRP Report 615:Evaluation of the Use and Effectiveness of Wildlife Crossings.Transportation Research Board of the National Academies,Washington, D.C., 2008. www.trb.org/news/blurb_detail.asp?id=9369.

9. Cramer, P. C., and J. A. Bissonette. Integrating WildlifeCrossings into Transportation Plans and Projects in NorthAmerica. In Proceedings of the 2007 International Conferenceon Ecology and Transportation, Little Rock, Arkansas. Cen-ter for Transportation and the Environment, North Car-olina State University, Raleigh, 2007, pp. 328–334.

10. Clevenger, A. P, and N. Waltho. Factors Influencing theEffectiveness of Wildlife Underpasses in Banff NationalPark, Alberta, Canada. Conservation Biology, 14:47–56,2000.

11. Clevenger, A. P., B. Chruszcz, K. Gunson, and J. Wierz-chowski. Roads and Wildlife in the Canadian Rocky Moun-tain Parks: Movements, Mortality, and Mitigation. FinalReport to Parks Canada, Banff, Alberta, Canada, 2002.

New Mexico Departmentof Transportation isretrofitting a bridgeunderpass in TijerasCanyon by widening ashoulder for wildlifepathways.

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2 NCHRP Project 25-27 was the basis for this article. 3 www.wildlifeandroads.org.4 http://environment.transportation.org/environmental_issues/wildlife_roads /decision_guide/manual/.5 www.icoet.net/.

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Saurenman is President,ATS Consulting, LosAngeles, California;Alexander is a NoiseSpecialist, FederalHighway Administration,Washington, D.C.; andNicholas Miller is SeniorVice President, HarrisMiller Miller & Hanson,Burlington,Massachusetts.

Before the National Environmental PolicyAct (NEPA) was signed into law in 1970,the effects of transportation-related noiseon the public were not a consideration in

Federal-Aid rail, highway, or airport projects. NEPAwas pivotal in raising awareness of the environmen-tal impacts of Federal-Aid projects. After NEPA wasenacted, the public benefited from additional federaland state laws and regulations, as well as from poli-cies addressing transportation noise and publicinvolvement.

Public outreach and land use compatibility aretwo approaches still evolving to address transporta-tion-related noise. Public outreach to minimize theimpact of transportation noise on nearby residentsrequires flexibility. The main purposes of outreachare to inform the public and local officials about thenoise impacts of a proposed project; to obtain inputon proposed measures for noise abatement; and toeducate public officials about planning and land use

controls to avoid and minimize the impacts of trans-portation noise.

Educating the public and public officials aboutthe importance of land use compatibility is essentialin preventing the impacts from noise. The rail tran-sit and highway noise industries coordinate theirtransportation projects with the public and local offi-cials, and the aviation industry examines noise andland use compatibility in a proactive approach tonoise abatement and impact avoidance.

Rail Transit NoiseNoise from proposed rail transit projects can be amajor concern—and an emotional issue—for com-munities adjacent to a proposed transit corridor. Per-haps the worst case is when a transit line is routedalong an abandoned or lightly used freight-rail cor-ridor that passes the backyards of residences.Although the rail corridor was there already, the res-idents do not want noisy trains regularly passingtheir backyards.

The footprint of the noise impacts can be mini-mized with appropriate abatement measures, andtransit corridors can be compatible with noise-sen-sitive land uses—communicating this possibility,however, can be difficult. A common misconceptionis that trains are loud—whether streetcars, light rail,or commuter or freight trains, and whether travelingat 25 mph or 100 mph.

Communities may be more receptive to urbantransit, such as streetcars or light rail, if lines alreadyserve the region and the benefits are easy to see. Thisis particularly true when extensive transit-orienteddevelopment occurs, even in such unlikely areas asSouthern California—according to conventional wis-dom, Californians would never give up their auto-mobiles to ride transit.

Public Outreach on Noise Impacts fromTransportation ProjectsCommunicating and Improving Measures for Transit, Highways, and Airports

HUGH SAURENMAN, ADAM ALEXANDER, AND NICHOLAS MILLER

The State Route 161NeXT (NortheastExpresswayTransformation) projectin Franklin County, Ohio,in 2004, included noisewall construction.

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Engaging CommunitiesTypical ways to engage communities include out-reach meetings for new projects, focused presenta-tions to small groups, and detailed responses topublic comments. Comprehensive technical reportscan aid these efforts, demonstrating that the com-munity’s concerns about noise have been taken seri-ously and that the noise issues are being addressed.

Interactive audio demonstrations also are effec-tive. A carefully designed demonstration can helppeople put the noise from a proposed transit lineinto context and understand their personal expo-sure. Several computer programs are available to sim-plify the preparation of an audio demonstration.Although audio demonstrations can educate peopleeffectively about transit noise and can help defusefalse preconceptions, the demonstrations must becarefully vetted to ensure that they convey theintended message accurately and that project oppo-nents cannot distort the message.

Abatement at the SourcesMost noise complaints received by transit systems arecaused by one of four sources:

� Wheel–rail noise, the normal noise of steelwheels rolling on steel rails;

� Wheel squeal generated in tight radius curves;� Audible warnings, such as horns or bells, that

alert pedestrians and motorists to trains approachinga highway–rail grade crossing; or

� The noise from wheel impacts on the specialtrackwork for crossovers and turnouts.

Effective abatement measures apply to all of thesesources—this is a key point to communicate. Of thenoise sources, only the wheel–rail noise occursthroughout the project corridor. The adverse effectsof the other sources are limited to localized areas.

The measures for reducing rail transit noise range

from noise barriers to lubrication that controls wheelsqueal. The measures ensure that the noise levelswill be much lower than on older systems thatstarted operation as many as 60 years before the envi-ronmental regulations required consideration ofnoise impacts.

Highway Traffic Noise From its inception after the Federal-Aid HighwayAct of 1970, Title 23 of the Code of Federal Regula-tions Part 772 (23 CFR 772) has provided state high-way agencies (SHAs) with flexibility in interpretingthe regulation to fit needs and program requirements.To be eligible for federal funding, noise abatementmust be feasible and reasonable; SHAs, however,have flexibility in evaluating the reasonableness andfeasibility of a measure for the properties affected.

Reasonableness includes the noise abatementcosts in relation to the benefits. In Highway TrafficNoise Analysis and Abatement Policy and Guidance,published in June 1995, the Federal HighwayAdministration (FHWA) recommends a range of$15,000 to $50,000 per benefiting residence as anupper limit for cost reasonableness. In 23 CFR772.11(f), the regulation identifies the views of thepublic—that is, public opinions, preferences, ordesires—as the primary consideration for reason-ableness.

The FHWA noise guidance states that “thereare…no easy methods to determine residents’ views orto arrive at a conclusion regarding residents’ desires.”States must determine how best to comply with theregulation. Each state has developed methods to deter-mine the public’s desire for noise abatement. Twoexamples demonstrating this flexibility follow.

Baltimore Light Rail Line train with noise barrier.

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A sign at a railroad gradecrossing alerts passersbythat trains on the SantaClara TransportationAuthority’s Vasona Linedo not use horns whencoming through thisresidential area inCampbell, California.

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Wisconsin: Reaching Residents and OfficialsThe Wisconsin Department of Transportation (DOT)holds public informational meetings (PIM), invitingresidents who live within 500 feet of the roadway, aswell as those who live opposite the proposed locationof a noise barrier. The department provides a list ofpreapproved noise barrier products to the public andexplains that the contractor will select the barrier type.

The Wisconsin Administrative Code (ChapterTrans 405) requires Wisconsin DOT to work closelywith local officials in siting a noise barrier. Trans405.05 specifies those who should be invited by mail

to the PIM. Trans 405 also requires the local unit ofgovernment to enact land use controls and to passa resolution of support before the noise barriers areincluded in the plans, specifications, and estimatesfor the project. Wisconsin DOT only constructs noisebarriers if the local officials meet these two require-ments.

Ohio: Mix of MethodsOhio DOT uses a mix of outreach methods thatinclude noise-specific public meetings, mailed sur-veys, and door-to-door surveys; it may use one or all

Aspecial program of the Federal Highway Administration(FHWA) allows for flexibility in strategies to abate high-

way traffic noise. Jointly developed by FHWA and the Ari-zona Department of Transportation (DOT), the QuietPavement Pilot Program (QPPP) has allowed Arizona DOT touse quieter pavements as a noise abatement option. TheQPPP is a voluntary program open to any state; require-ments include evaluating the changes in the pavement’snoise abatement properties over time and making a com-mitment to maintain in perpetuity any noise reductionattributed to the pavement.a

After preliminary studies, Arizona DOT decided to demon-strate the effectiveness of asphalt rubber friction course (ARFC)as a noise abatement strategy in the metropolitan Phoenixarea.b Arizona DOT had used ARFC since 1988, but the prod-uct’s noise-reducing capabilities—a positive side effect—hadbeen identified only recently. Another benefit to the environ-ment is that more than 15 million tires have been recycledsince 1988 by paving Arizona highways with ARFC. On thePhoenix freeways, Arizona DOT applied a 1-inch-thick layer ofARFC, which has a 20 percent content of tire rubber, on top ofconcrete pavement that was 12 to 14 inches thick.

The QPPP includes measurements to evaluate the noise-reducing capabilities of ARFC as the pavement ages. Through-out the project area, source measurements close to thetire–pavement interface have shown reductions from trans-versely tined concrete averaging 6 dBA in the sound intensitylevel, stabilized after a few years of pavement service; initiallythe reductions measured an average of 8 dBA.

At select research sites, wayside measurements adjacent tothe highway—50 feet from the near travel lane—have shown

noise reductions from transversely tined concrete averaging 9dBA in sound pressure after 1 year of service; limited datashow this average declines approximately 1 dBA per year overa few years. When the measured data are compared with pre-dictions from the FHWA Traffic Noise Model for average pave-ment, the ARFC would provide an average reduction of 4 dBAin sound pressure level after 1 year of service. This comparisonis significant in investigating the inclusion of pavement effectsin noise impact analyses. Arizona DOT will continue to evalu-ate the acoustic longevity of ARFC through the life of the pave-ment.

The author is Physical Scientist, Volpe NationalTransportation Systems Center, Research and InnovativeTechnology Administration, Cambridge, Massachusetts, andchairs the TRB Transportation-Related Noise and VibrationCommittee.

Arizona Tests Quieter Highway Pavement

J U D I T H L . R O C H A T

Treated with rubberized asphalt, I-10, a busy highway inmetropolitan Phoenix, has lowered noise levels for nearbycommercial and residential areas.

a For more information, see www.fhwa.dot.gov/environment/noise/qpppmem.htm.b For more information on Arizona DOT’s QPPP, seewww.quietroads.com/.

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of these methods to obtain a complete view of theopinions of affected residents. To combat poorturnout for public meetings or low response rates tothe surveys, Ohio DOT districts may use a mixedpublic involvement approach—sending detailedproject information and surveys along with the pub-lic meeting invitations. This allows affected residentsto make informed decisions and to provide aresponse without attending the public meetings. Thesurvey typically includes aesthetic options andgauges the desire for noise abatement.

Simple surveys, such as a self-addressed postcardasking a resident to check yes or no, also may helpin the decision-making process. The tool may be use-ful when traditional surveys and public meetings donot achieve sufficient levels of public input or if thegoal is to gauge public interest in noise abatementearly in the public involvement process.

Communication CaveatsSHAs should be cautious in repeating attempts todetermine the public’s desires. Advocates for andagainst noise barriers may accuse the SHA of takingadditional surveys only to obtain the answer that theSHA wants. The lack of response from a neighbor-hood does not necessarily indicate a lack of interestin noise abatement—a poor public response may bethe result of insufficient public outreach by the SHA.Understanding what method to use, and when,requires experience and a project team that knowsthe constituents.

Aviation Noise Airports and surrounding jurisdictions can improvenoise levels and land use compatibility with the bal-anced approach that is favored internationally. Thisapproach seeks to achieve land use compatibilityaround airports through five initiatives:

� Quieting the planes, � Land use planning,� Airport layout,� Noise abatement procedures, and� Restrictions on operations.

Until major technological advances occur, the air-craft now being manufactured are as quiet as they canbe. Land use planning has restricted noise-sensitivedevelopment from areas with noise levels above 65dB DNL (the day–night average sound level) and hasrecommended sound insulation for residential areas.1

Noise abatement procedures are effective in some

cases but often involve trade-offs. Changes in airportlayouts are infrequent and are influenced mostly bycapacity considerations, not by noise compatibilitygoals. Restrictions on aircraft operations are rarelyachievable.

Because the other methods can yield only smallimprovements, more creative approaches are neededfor land use planning. Land use compatibility mea-sures traditionally have limited or prevented noise-sensitive land use when aircraft noise exposuresexceed 65 dB DNL. Airports and local jurisdictions,however, discovered long ago that adhering to thiscriterion is not sufficient for many communities—the public still may express dissatisfaction and likelywould oppose any noise increase.

As a result, although compatibility may have beenachieved in terms of the 65 dB DNL threshold (1),airports still may find that they cannot operate orseek to increase operations without encounteringsignificant opposition from the surrounding com-munities. The primary need is for airports to workcooperatively with the surrounding communities todevelop their own land use compatibility zoning orplanning.

The most important, yet difficult, step to achiev-ing this type of airport and community compatibil-ity is the selection of the criteria for noise and landuse.

Virtually all airports and jurisdictions use DNL inplanning, but DNL is not directly related to whatpeople hear and cannot convey the number or levelsof aircraft-produced noise events.

Table 1 (next page) presents hypothetical—butcomputationally accurate—relationships between anoise level of 65 dB DNL and maximum aircraftsound levels, numbers of operations, and the approx-imate times that aircraft sound levels would exceed 60dB(A)—the level at which interference begins withhearing speech. An average outdoor maximum levelof 95 dB(A) might occur near the end of a commer-cial jet departure runway; a level of 85 dB(A) at about1 mile from the runway; and a maximum of 75 dB(A)at about 3 to 4 miles from the end of the runway.

Clearly, 65 dB DNL will not always produce thesame noise environment. Most people would preferto live in a location with 10 aircraft operations perday, even if the operations are loud, than in one with100 or 1,000 quieter operations per day.

Land use compatibility criteria, therefore, shouldaccount for different aircraft noise environments.The original recommendations for compatibility,developed in the early 1970s, were based on theeffects of the noise levels on people (2). Muchresearch on noise effects has been published sincethen, and the information is sufficient to develop

The Orlando AviationAuthority and AviationNoise AbatementCommittee prepared abrochure about airportnoise for residents livingnear Orlando airports.

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associations between DNL and effects similar tothose presented in Table 2 (below). The actual per-centage of population and number of events shownin this table depends on the number and type of air-craft operations, the population distributions aroundthe airport, and other assumptions, such as the out-door-to-indoor sound level reductions provided bytypical homes, whether residents sleep with win-dows open or closed, whether the homes are air con-ditioned, and the numbers of nighttime operations.

Decisions about the compatibility criteria that arebest for a jurisdiction can be based on more than thecommonly used threshold of 65 dB DNL or the sub-jective understanding of how residents respond toDNL values. The effects can be quantified and judg-ments can be made with knowledge of how noise islikely to affect people. These numbers are differentfor each airport and jurisdiction, and the criteria canbe based on community benefits with respect to theairport, instead of following a one-size-fits-allapproach.

The selection of land use compatibility criteriafor a jurisdiction, therefore, is a policy decision for

local officials and citizens. Quantifying the effectscan help make this an informed decision and canprovide an important logic trail for future legaldefense.

Airports and jurisdictions working cooperativelyon noise and land use compatibility plans maydevelop understandable quantities associated withvalues of DNL—for example, percent or numbers ofpeople highly annoyed, or percent or numbers ofpeople awakened. Instead of determining compati-bility criteria by arbitrarily choosing a value of DNLor by using the traditional 65 dB DNL, decision mak-ers can develop noise compatibility policy that lim-its the effects of noise on the local population.

References1. Airport Noise Compatibility Planning. 14 CFR Part 150.

www.faa.gov/airports_airtraffic/airports/environmental/airport_noise/.

2. Impact Characterization of Noise, Including Implications ofIdentifying and Achieving Levels of Cumulative Noise Expo-sure. EPA Report No. NTID 73.4,Task Group 3 (H. E. vonGierke, Chair), Environmental Protection Agency, Wash-ington, D.C., July1973.

TABLE 2 Estimated Noise Effects for an Average Day at a Large Air Carrier Airport

Percent of Population… Number of DailyAircraft Events That…

DNL Awakened at Interfere with Cause FeelableRange Least Once by Highly Conversation House(dB) Aircraft Annoyedb Indoors Vibrationc

Noisea (Windows Open)

>70 >40% >40% >250 >200

65–70 35–40% 30–40% 100–250 50–200

60–65 30–35% 20–30% 50–100 <50

55–60 20–30% 10–20% <50 negligiblea Based on ANSI Standard S12.9-2008, Quantities and Procedures for Description and Measurement of Environmental Sound,Part 6: Methods for Estimation of Awakenings Associated with Outdoor Noise Events Heard in Homes.

b Annoyance is determined from well-established averages for aircraft noise only. See Miedema, H. M. E., and C. G. M.Oudshoorn. Elements for a Position Paper on Relationships Between Transportation Noise and Annoyance. TNO ReportPG/VGZ/00.052, Leiden, Netherlands, July 2000.

c Based on ANSI Standard S3.29-1983, American National Standard Guide to the Evaluation of Human Exposure to Vibration inBuildings.

TABLE 1 Combinations of Maximum Aircraft Levels and Operations That Create 65 dB DNL

Maximum Required No. Approximate ApproximateAircraft of Operations Time Above Total Time

Sound Level in 24 hours 60 dB(A), Above 60(None at Night) Each Operation dB(A) dB(A)

95 dB(A) 10 50 seconds 8 minutes

85 dB(A) 100 35 seconds 1 hour

75 dB(A) 1,000 20 seconds 6 hours

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Opperman is PreservationProgram Manager, Environmental Division, Virginia Department ofTransportation, Richmond,and Chair of TRB’s Historicand Archaeological Preser-vation in TransportationCommittee; Luhman isAssistant Director, CulturalResources, The LouisBerger Group, Inc., Albany,New York; Pettis is Archi-tectural Historian, Meadand Hunt, Inc., Madison,Wisconsin; and Stoermer isEnvironmental ProgramSpecialist–Archaeologist,Federal Highway Adminis-tration, Lakewood, Colo -rado.

An efficient and effective transportationsystem does not necessarily conflict withthe preservation of the past. Elements ofthe transportation system are manifesta-

tions of the nation’s history—historic properties intheir own right. Yet accommodating historic preser-vation issues sometimes can be one of the mostdaunting environmental challenges in transporta-tion. Research on historic preservation in trans-portation aims to offset these challenges.

Historic preservation issues in transportationlargely result from legal and regulatory requirementsat the national, state, and local levels. Among themost recognized authorities driving historic preser-vation issues in transportation are the National His-toric Preservation Act (NHPA), especially Section106; the National Environmental Policy Act; Section4(f) of the Department of Transportation Act; and the

historic preservation requirements of the Safe,Accountable, Flexible, Efficient TransportationEquity Act: A Legacy for Users (SAFETEA-LU). Alsoexerting influence are authorities at the state, local,and agency levels.

With this range of requirements, much of thefocus of historic preservation research in transporta-tion is on legal and regulatory performance. Theresearch is applied in a specific area to improve trans-portation project delivery and the stewardship of his-toric assets involved in the transportation system.

The members and friends of the TransportationResearch Board’s (TRB) Historic and ArchaeologicalPreservation in Transportation Committee exemplifythe backgrounds and experience of those involved inhistoric preservation research in transportation—pro-fessionals in archaeology, history, architectural history,architecture, and engineering. This diverse expertise

Transportation and Historic Preservation Progress and Research

ANTONY F. OPPERMAN, HOPE E. LUHMAN, EMILY PETTIS, AND STEPHANIE STOERMER

The Monocacy Aqueductin Maryland was built inthe 1830s, but stormscaused major damage,and unsightly exteriorsteel bracing was neededto stabilize the structure.The National Park Serviceremoved the exteriorbracing and stabilized theaqueduct internally, and itwas reopened in 2005.

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typically derives from the private sector, national andstate public transportation agencies, public historicpreservation organizations, and aca demia. In additionto TRB, organizations such as the American Associa-tion of State Highway and Transportation Officials(AASHTO), transportation research partnershipsbetween public transportation agencies and universi-ties, and the Federal Highway Administration(FHWA) play a significant and interrelated role insponsoring historic preservation research.

Research AccomplishmentsAlthough historic preservation research interests intransportation are diverse, three areas deserve par-ticular attention.

Evaluating Historic SignificanceThe designation of historic status is one of the mostfundamental decisions in historic preservation,regardless of any relationship to transportation. Allsubsequent decisions required by law and regulationthat involve the effects of a project and the measuresto mitigate those effects derive from the property’sdesignation as historic. Most commonly the desig-nation involves a finding that a building, structure,bridge, district, site, or object is eligible for listing inthe National Register of Historic Places (NRHP) inaccordance with regulatory requirements1 and prac-tices established by the National Park Service (NPS).Although the National Register has been in placesince 1966, and considerable guidance is available,the decision about eligibility can be subjective,inconsistent, and time consuming.

Several key research efforts and products in thepast decade reflect the importance of the decisionabout historic status. In 1999, TRB’s Historic andArchaeological Preservation in Transportation Com-mittee, with assistance from FHWA and NPS, orga-

nized the National Forum on Assessing Historic Sig-nificance for Transportation Programs (1). The ses-sions led to three research projects on improvingdecision-making performance:

� National Cooperative Highway Research Pro-gram (NCHRP) Project 8-40, Evaluating CulturalResource Significance Using Information Technol-ogy (IT), which surveyed IT applications (2);

� A project to develop a model IT application(3); and

� NCHRP Project 25-25, Task 33, National Reg-ister of Historic Places Eligibility, which evaluatedpractices nationwide (4).

Success in this area can be measured by the con-tinuing emphasis—in workshops, research projects,and publications—on careful and systematicapproaches to decision making by the federal and statetransportation agencies. Transportation agencies’ focuson their “ownership of responsible decision making”is a significant improvement over previous practices.

Managing the Recent PastDecisions on historic status usually involve proper-ties that are more than 50 years old—an approachthat is designed to separate careful consideration ofhistoric significance from the influence of nostalgia.The 50-year horizon, however, increasingly encom-passes buildings, structures, and districts built in thepost-World War II years. In some parts of the UnitedStates, the rate of increase in these properties is expo-nential—especially in the suburbs of major metro-politan areas.

Complicating the subjective tendency of conven-tional decisions about what should be consideredhistoric are personal relationships with properties“like the one I grew up in,” the mass production ofthose properties, and the increasing number of prop-erties that transportation projects must deal with.This situation intensifies with the passing of eachyear and may affect the delivery of transportationprojects significantly.

An important example of applied research tomanage the recent past is the work conducted byFHWA to support the exemption of the InterstateHighway System, now crossing the 50-year thresh-old, from eligibility for listing in the National Regis-ter of Historic Places, in accordance withSAFETEA-LU Section 6007. The research developeda national context for consultation with state his-toric preservation officers to identify properties towhich the exemption would not apply (5). FHWA’sresearch defined only 143 individual Interstate sys-tem elements that are considered historic and sup-1 36 CFR Part 65.

This suspension bridge inNishanic Station, NewJersey, fell into disrepairand was in danger ofbeing demolished.Instead, the 1897 bridgewas rehabilitated, withcare taken to keep itslenticular truss structureunchanged.

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ported a significant statutory streamlining of historicpreservation involvement with the Interstate system.

Although NPS has issued limited guidance, theTRB Historic and Archaeological Preservation inTransportation Committee has worked to bringattention to the potential impact of the nation’s morerecent history on transportation project delivery. Thecommittee has sponsored a series of conference ses-sions and workshops to explore how the issue isbeing expressed and managed across the country.The research community is ready to assist in man-aging the recent past efficiently in a proactive part-nership with the historic preservation community.

Historic Bridge PreservationHistoric bridges are integral elements of the trans-portation system, and interest in historic bridges inthe United States has been a long-term theme of boththe transportation and the historic preservation com-munities. Much of this mutual interest, however, hasbeen expressed in sometimes impassioned debatesbetween the two communities. Research efforts at thenational and state levels therefore have turned topragmatic approaches to achieve balanced consider-ation of transportation and preservation needs.

Historic bridge research has focused largely onfour areas: historic context development, historicbridge inventories, management and preservationplans, and rehabilitation practices. Although manystates have their own context studies of historicbridges, an NCHRP project produced a notable, up-to-date national study (6). The NCHRP project builtnot only on several decades of research at the statelevel but also on efforts by state DOTs to inventoryhistoric bridges.

All 50 states have prepared historic bridge inven-tories—although the levels of comprehensivenessmay vary (see box, page 28). In addition, many stateshave made progress in managing historic bridgesthrough preservation plans or programmatic agree-ments developed in cooperation with preservationpartners.

The goal of research, however, is to influencewhat happens in the outside world, and manydepartments of transportation (DOTs) are now morecapable and inclined to consider the rehabilitation,instead of the replacement, of historic bridges. Theinterest in rehabilitation is reflected in Guidelines forHistoric Bridge Rehabilitation and Replacement (7) andin the progress that DOTs have made in completinghistoric bridge inventories and developing manage-ment plans.

Also of interest is the growing awareness that theaesthetics of new bridges in historic areas can bene-fit from context-sensitive solutions (CSS) to avoid

introducing false historic elements or design featuresthat would have an effect on adjacent historic prop-erties. A session at the 2008 TRB Annual Meeting,Context-Sensitive Solutions and Bridge Aesthetics:Procedures That Underlie Successful and Cost-Effec-tive Designs, may prove to be pivotal in integratingthose issues. The increased willingness of trans-portation engineers and historic preservation pro-fessionals to engage in dialogue about historic bridgeissues is fundamental to progress in this area.

Looking into the FutureThe trends established through past research accom-plishments will continue as best practices are refinedand as new technologies bring greater efficiency andstreamlining to the historic preservation reviewprocess for transportation projects.

In some respects, historic preservation was hin-dered by its own success, as the information fromdecades of local research and regulatory reviews cre-ated a burgeoning, but data-rich, knowledge base.Geographic information systems, web-enabled datasystems, and other digital technologies haveimproved information access significantly, are con-tributing to analytical efficiency, and are an importantmeans to identify future research needs.

Research InitiativesThe TRB Historic and Archaeological Preservation inTransportation Committee and AASHTO’s StandingCommittee on the Environment have identified 26historic preservation research needs in transportation.Of the 26, four have been completed, two are underway; the rest are unmet. In addition, FHWA’s SurfaceTransportation Environment and Planning Coopera-tive Research Program (STEP) has identified tworesearch needs. The four projects under way are thefollowing:

� Integrating Cultural Resource Managementand Historic Preservation into Transportation Plan-ning (AASHTO; NCHRP);

� Implementation of Cultural Resource Com-mitments (AASHTO; NCHRP Project 25-25, Task41);

� Research and Innovation Agreement withAdvisory Council on Historic Preservation (FHWA-STEP); and

� Consideration of Historic Preservation in EarlyPlanning (FHWA-STEP).

The primary focus of these projects is on stream-lining the legal and regulatory processes in historicpreservation that directly influence transportationproject delivery. This can be accomplished by iden-

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To inform the national dialogue about historic bridgepreservation and to encourage continued management

of significant structures, historic preservation specialists withMead & Hunt, a multidisciplinary consulting firm, recentlyundertook a national study of historic bridge practices incooperation with the Historic Bridge Alliance. Completedbetween February and June 2008, the survey addressedbridge preservation and management practices in eachstate, including inventories, rehabilitation projects, successesand challenges, and future bridge management activities.Respondents included state departments of transportation(DOTs), state historic preservation offices, and Federal High-way Administration representatives.

Historic bridge inventories and preservation plans repre-sent an effort by DOTs to comply with federal requirements forthe inventory, rehabilitation, and potential adaptive reuse ofhistoric bridges.a Compliance with environmental require-ments—such as with Section 106 of the National PreservationAct and Section 4(f) of the Department of Transportation Actof 1968—also can be streamlined by proactively and compre-hensively defining the universe of historic bridges and reach-ing a consensus about their management.

The survey results are expected to help state DOTs and otheragencies understand how their state’s practices fit into thenational spectrum of historic bridge survey, evaluation, andpreservation planning. The survey allows agencies to see whattheir counterparts are doing, as well as what strategies, tech-niques, and policies are working in other states, enabling pro-cedural improvements.

Highlights of the survey results demonstrate progress innational bridge preservation and include the following:

� All 50 states have completed historic bridge inventories;however, not all have been comprehensive—21 states havelimited their historic bridge inventories to specific materials

or bridge types, and most historic bridge inventories onlyaddress bridges built between 1900 and 1945.

� State DOTs primarily use management plans and pro-grammatic agreements to fulfill their regulatory responsibili-ties and to administer statewide historic bridge programs.Although fewer than half of the states have completedbridge-specific management plans to guide preservationefforts, many states recognize their value, and 20 statesintend to complete historic bridge management plans.Nineteen states have developed programmatic agreementsto address historic bridges comprehensively under Section106. Other states have programmatic agreements thataddress individual bridge types or that serve as tools for stip-ulating acceptable repair work.

� Survey respondents identified five primary challenges tohistoric bridge programs: lack of funding, lack of agencypreservation commitments, inability to identify adaptivereuses, lack of education about historic bridges, and theinability of bridges to meet current design criteria. Despitethese challenges, two-thirds of state DOTs report theirapproach to addressing historic bridges has been effective.

� Most states wish to accomplish more with their pro-grams; future initiatives include inventories, managementplans, education, programmatic agreements, and rehabilita-tion projects.

For more information on the survey results, contact preservation@meadhunt.com or visit www.meadhunt.com/documents/newsletters/HistoricBridgePractices.pdf.

Pettis and Long are architectural historians with Mead &Hunt, Inc., Madison, Wisconsin.

a 23 U.S.C. 144(o).

Preserving Bridges NationwideImproving on the Past

E M I L Y P E T T I S A N D C H R I S T I N E L O N G

Local historic groups protested the proposed replacement of this1905 bridge over the St. Joseph River in South Bend, Indiana. St.Joseph County agreed to rehabilitate the bridge instead and keep itin use.

Number of states that have taken steps toward bridge preservationprograms.

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tifying best practices for regulatory review, aug-menting survey and planning efforts through tech-nological innovation, and applying programalternatives that are consistent with the law and reg-ulation. These projects cover the spectrum from theearly consideration of historic preservation concernsin planning, to innovative administrative streamlin-ing during project development, to strengtheningthe tracking of commitment performance.

Unmet Research NeedsMany of the unmet research needs are as importantas the ongoing studies of potential process improve-ments. Although historic preservation interests intransportation are diverse, the most important needsinclude

� Effectively managing the recent past,� CSS and historic properties, and� Best practices in the rehabilitation of historic

bridges.

As noted earlier, the exponential increase in thenumber of properties at or beyond the 50-year thresh-old for consideration as historic could overwhelmthe capacity of transportation agencies and their his-toric preservation partners—despite improvementsmade in the regulatory processes. The most importantemerging transportation research need, therefore, is tofind ways to manage the recent past effectively, by effi-ciently determining which properties are historic, andby developing historic contexts to target the signifi-cant aspects of the nation’s recent past and determineNRHP eligibility. The recently approved NCHRP Proj-ect, Developing Regional Historic Contexts for Post-World War II Housing, should make significantprogress in this area.

Informing PracticeResearch should not focus exclusively on streamlin-ing decision making and regulatory process improve-ments, however. The growing interest in andapplication of CSS in the design of transportationprojects can benefit from an enhanced understand-ing of the role of historic properties in defining con-text. Research to review applications of CSS practicein relation to historic properties would help definebest practices and principles of practice.

Research has contributed to improvements in his-toric bridge preservation. The transportation com-munity will face additional challenges as theinfrastructure continues to age and as fundingbecomes more competitive.

The continued collaboration between the historicpreservation and engineering communities could

focus on defining innovative and financially respon-sible best practices and making that informationaccessible to practitioners. FHWA and AASHTO, forexample, have developed a web-based community ofpractice to communicate innovative engineering andpreservation approaches—a method of disseminat-ing research that can directly influence transporta-tion project decision making and facilitate therehabilitation of that nation’s historic bridges.

References 1. Klein, T. H., and L. Sebastian. Transportation Research Cir-

cular E-C055: National Forum on Assessing Historic Signif-icance for Transportation Programs. Transportation ResearchBoard of the National Academies, Washington, D.C., 2003.http://onlinepubs.trb.org/Onlinepubs/circulars/ec055.pdf.

2. NCHRP Research Results Digest 277: Review and Improvementof Existing Processes and Procedures for Evaluating CulturalResource Significance, Transportation Research Board of the National Academies, June 2003. http://onlinepubs.trb.org/Onlinepubs/nchrp/nchrp_rrd_277.pdf.

3. Edwards, M. R., R. L. Peer, E. Lindner, and T. H. Klein.NCHRP Report 542: Evaluating Cultural Resource Signifi-cance: Implementation Tools. Transportation Research Boardof the National Academies, Washington, D.C., 2005. http://onlinepubs.trb.org/Onlinepubs/nchrp/nchrp_rpt_542.pdf.

4. The SRI Foundation and ICF International. National Reg-ister of Historic Places Eligibility. Final Report, NCHRPProject 25-25, Task 33. Transportation Research Board ofthe National Academies, Washington, D.C., November 30,2007. www.trb.org/NotesDocs/25-25(33)_FR.pdf.

5. Federal Highway Administration and The Louis BergerGroup. The Interstate Highway System in the United States:Draft Final Historic Context Report. U.S. Department ofTransportation, December 2004.

6. Parsons-Brinckerhoff and Engineering and Industrial Her-itage. A Context for Common Historic Bridge Types. FinalReport, NCHRP Project 25-25, Task 15, TransportationResearch Board of the National Academies, 2005.www.trb.org/NotesDocs/25-25%2815%29_FR.pdf.

7. Lichtenstein Consulting Engineers, Inc. Guidelines for His-toric Bridge Rehabilitation and Replacement. Final Report,NCHRP Project 25-25, Task 19, Transportation ResearchBoard of the National Academies, 2007.

Postwar contemporary-style house in Oshkosh,Wisconsin, constructedcirca 1956. A recentlyapproved NCHRP projectwill develop regionalhistoric contexts forhousing built after WorldWar II.

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T he Center for Transportation and the Environment(CTE), North Carolina State University (NCSU), and North

Carolina Department of Transportation (DOT) have part-nered on initiatives to train graduate and undergraduateengineering students in developing and applying context-sensitive solutions (CSS). The programs provide studentswith valuable experience for their transportation careers,including connections with employers and colleagues.

CSS Summer AcademyIn cooperation with North Carolina DOT, CTE conducts an expe-riential summer program for junior- and senior-level under-graduates interested in careers in transportation and theenvironment. The Context-Sensitive Solutions Summer Acad-emy introduces the principles of CSS and their applications intransportation planning, project development, construction,operations, and maintenance.

Joe Hummer and John Stone, ofthe NCSU Department of Civil, Con-struction, and Environmental Engi-neering, lead the Academy studentsthrough coursework, case study activ-ities, and research projects. Field tripsshowcase real-life applications of CSSacross the state. The students alsowork as summer interns for NorthCarolina DOT, in positions thatdirectly address transportation andenvironmental concerns.

At the conclusion of the Acad-emy, students make final presenta-tions of their findings to a group ofNorth Carolina DOT staff, other pro-fessionals, and university faculty. Thirty-two undergraduatejuniors and seniors have completed the Academy successfullysince its start in 2004. Academy students have researched andanalyzed more than 50 different North Carolina DOT projects.

In 2007 and 2008, the Context-Sensitive Solutions SummerAcademy focused on research into the costs and benefits ofCSS. Students collected data and background information onprojects from documents and structured interviews with NorthCarolina DOT project managers. The assignments allowed stu-dents to investigate issues of current interest in the industry,gain experience in transportation research methodology, andlearn about a range of project types in North Carolina. A stu-dent presented a report on the 2007 Academy to the TRB Con-text-Sensitive Design and Solutions Task Force at the TRB 86thAnnual Meeting.

CSS Graduate CourseCTE and the NCSU Department of Civil, Construction, and Envi-ronmental Engineering have launched a new course for grad-uate students on CSS principles and practices. Designed andtaught by Hummer and Stone, the course imparts hands-onexperience with CSS principles by applying the core practices ofCSS, including comprehensive identification of context, linkeddecision-making, stakeholder involvement, use of multidisci-plinary teams, and comprehensive documentation.

During the first session, student teams worked with a proj-ect in Wrightsville Beach, North Carolina. The teams studied theproject and the community context and then applied flexibledesign approaches to develop alternatives. The teams pre-sented the alternatives at a mock citizens’ workshop to role-playing North Carolina DOT employees, representing variouscommunity groups and concerns.

Equipping the WorkforceBoth the Academy and the graduate-level course are part ofCTE’s commitment to educate and equip the next-generationtransportation workforce. The programs allow students toenhance their engineering education and to start their careerswith valuable insights into the project development processand with experience in addressing environmental and com-munity concerns.

For more information on CTE programs, visit www.cte.ncsu.edu/CTE/Education/index.asp.

The author is Associate Director, Center for Transportationand the Environment, North Carolina State University,Raleigh.

Introducing Context-Sensitive Solutions to theNext Generation of Transportation Professionals

J A M E S B . M A R T I N

CSS students viewenvironment-friendlysolutions incorporatedinto the WilmingtonBridge.

CSS Summer Academy students follow a hands-on program thatcombines coursework, case study activities, research projects,internships with North Carolina DOT, and field trips, culminating ina final project report.

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The author is SeniorProject Scientist,Illingworth & Rodkin,Inc., Petaluma,California.

Pile driving at large construction sites pro-duces formidable noise. Marine pile driv-ing similarly can produce high soundpressures underwater—but these can be

lethal to fish and can harass marine mammals,including those protected by federal law. This prob-lem has contributed to costly construction delays onmajor bridge projects. To protect marine life, engi-neers have designed air bubble curtains to reduceunderwater sounds.

Problem In 2000, the California Department of Transportation(Caltrans) undertook a demonstration project toinstall steel piles as part of the design to replace theeastern span of the San Francisco–Oakland BayBridge. The demonstration involved driving 8-foot-diameter steel piles that were more than 300 feetlong. The new bridge would require more than 250of the piles.

Caltrans also conducted tests on sound reduc-tion methods that had been developed to protectmarine mammals. The underwater sounds duringthis demonstration, however, fatally injured fish,which were observed floating on the surface andexposed to predation by seagulls. Because the soundreduction methods were not protecting the fish ade-quately, state and federal agencies raised concernsabout the endangered fish species in the area.

While the designers were working on develop-ing an air bubble curtain that would effectively pro-tect fish, pile driving began on the nearby Benicia-Martinez Bridge, located in the Carquinez Strait, acritical migration route for endangered fish inNorthern California. Fish were fatally injured bythe construction noise. This caused additionalalarm and slowed the construction of the bridge.

The construction plans had not included meth-ods to reduce underwater sounds. The pile drivinghad been restricted to slack tide conditions, whenfish were least likely to be present, and was sus-pended when the endangered fish began theirmigration. The potential delay of 7 months threat-ened to stop the project permanently because offunding issues.

Solution and ApplicationAir provides an effective barrier to sound propagat-ing through water, because of the difference in den-sity between air and water. Air bubble curtainsystems have been used to reduce underwater soundpressures from explosions or from other sources ofhigh-amplitude sounds.

The first documented use of air bubble curtainson a marine pile-driving project was in Hong Kong;the curtains reduced the sounds by 3 to 5 decibels,protecting marine mammals (1). Engineers inCanada then reported favorable results with an airbubble curtain to protect fish at a wharf project. Cal-trans, however, faced several complications: thesound levels were much higher, the water was

Reducing Underwater Soundswith Air Bubble CurtainsProtecting Fish and Marine Mammals from Pile-Driving NoiseJ A M E S A . R E Y F F

R E S E A R C H P AY S O F F

An unconfined air bubblecurtain with twovertically stacked rings isdeployed on a harborproject to reduceunderwater sounds; oil-free compressors supplyair to the system.

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deeper, and the currents stronger. The curtain of airbubbles must be able to extend from the bottom ofthe pile to the water surface without any gaps.

Moreover, the driving templates that had beendesigned and fabricated for the project did not sup-port the use of available air bubble curtains. Engi-neers therefore developed two types of curtains.

Design VariationsFirst, they placed a perforated tube at the bottom ofa large cylinder that extended from just below themud line to above the water surface, with the pileinside. The large cylinder would prevent currentsfrom sweeping the air bubbles away from the pile.

Because many projects could not accommodatea large cylinder around the pile, multistage air-bubble curtains were developed. These systemsplace a series of rings around the pile at differentdepths. Although currents could sweep the bub-

bles away, the ring above would generate more bub-bles, maintaining a uniform presence of air aroundthe entire pile.

The prefabricated pile template for the Benicia-Martinez Bridge could not accommodate completerings. The engineers therefore developed stackedquarter-rings that were placed at each quadrant ofthe piles. Because of the water depth, large com-pressors were required to deliver air to the bottomof the water column.

Underwater sound tests were conducted forthese air bubble curtains with the air suppliesturned on and off. The sound was reduced by 20 to30 decibels close to the pile, where most of the fishinjuries had occurred (2). Tests on other projects inshallower waters measured reductions of 10 to 20decibels. In comparison, most highway noise bar-riers achieve reductions of only 5 to 10 decibels.

The key was that no fish injuries or mortalitywere observed with the air bubble curtains. Soundreductions from the pile driving were recorded outto 1 kilometer away. Areas with adverse effect onfish and marine mammals were estimated todecrease in size by up to 90 percent.

Research Group FormedWhile the engineers were working on an effectivedesign for the air bubble curtains against pile-driving sounds, researchers were trying to deter-mine the effects of the noise on fish. Highway andresource agency officials, expert consultants, anduniversity researchers formed the Fisheries Hydro -acoustic Working Group (FHWG), which releasedthe first research findings on the effects of sound onfish in 2005 (3). The group concluded that little was known and much additional research wasneeded.

In 2008, FHWG developed interim criteria toidentify the potential effects of underwater soundon fish. All impact pile-driving activities exceededthe sound levels at which the onset of impacts tosmall fish occurs. On bridge projects that usedlarger steel-pipe piles, the impacts could extend 1to 2 kilometers out into open water.

BenefitsUse of the air bubble curtains during pile drivinghas reduced sounds substantially. Biologists fromCaltrans have not identified any injured fish withthe air bubble curtains in use during pile driving. InSan Francisco Bay, pile driving has been permittedduring fish migration seasons, as long as the air bub-ble curtains reduce the sound levels sufficiently. Inthis way, pile driving that had been limited to sea-sonal windows can be completed before deadlines.

Example waveforms andfrequency spectra for 2.4-m-diameter steel pilewith and without bubblecurtain: Benicia-MartinezBridge, Carquinez Strait,California.

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Projects now incorporate efforts to reduce under-water sounds from pile driving. In addition to airbubble curtains, options include dewatered coffer-dams and other methods to install piles. Attenuationsystems that use air to reduce underwater sounds arein routine use on the West Coast for marine pile-driv-ing. Although the air bubble curtains can increase thetime and cost of pile driving, proper planning canminimize the delays.

The FHWG continues to research the effects ofsound on marine species and to develop more effec-tive techniques to reduce underwater sound frommarine construction. A National Cooperative High-way Research Program project is testing the effect ofpile-driving sounds on fish in a laboratory setting(see box, below). A pooled-fund study will investi-gate changes to pile designs that could reduce soundpressures.

The Federal Highway Administration presentedCaltrans and FHWG with a 2005 EnvironmentalExcellence Award. Caltrans and the WashingtonState Department of Transportation (DOT) havedeveloped guidance manuals for assessing theimpacts of pile driving before design, so that theappropriate measures to reduce sound can be incor-porated. Washington State DOT is investigatingmethods to reduce pile-driving sounds further, toallow pile driving year-round in waters with endan-gered or threatened species. For more information onthis topic and for copies of research documents, seethe Caltrans website, www.dot.ca.gov/hq/env/bio/fisheries_bioacoustics.htm.

For additional information, contact James A. Reyff,Illingworth & Rodkin, Inc., Acoustics–Air Quality,505 Petaluma Boulevard South, Petaluma, CA

94952; telephone: 707-766-7700, ext. 24; e-mail:jreyff@illingworthrodkin.com; or James R. Andrews,Senior Transportation Engineer, Division of Environ-mental Analysis, Caltrans; telephone: 916-653-9554;e-mail: jim_andrews@dot.ca.gov.

References1. Wursig, B., C. R. Greene, Jr., T. A. Jefferson. Development of

an Air Bubble Curtain to Reduce Underwater Noise of Per-cussive Piling. Marine Mammal Research, 49:79–93, 1999.

2. Reyff, J. A. Underwater Sound Levels Associated with Con-struction of the Benicia-Martinez Bridge: Acoustical Evalua-tion of an Unconfined Air-Bubble Curtain System at Pier 13.Illingworth & Rodkin, Inc., Petaluma, Calif., 2003.

3. Hastings, M. C., and A. N. Popper. Effects of Sound on Fish.2005.

4. Technical Guidance for Assessment and Mitigation of Hydro -acoustic Effects of Pile Driving on Fish. Caltrans, March 2009.www.dot.ca.gov/hq/env/bio/fisheries_bioacoustics.htm.

EDITOR’S NOTE: Appreciation is expressed to StephenMaher, Transportation Research Board, for his effortsin developing this article.

More Clues from the LabNational Cooperative Highway Research Pro-gram Project 25-28, Predicting and Mitigat-ing Hydroacoustic Impacts on Fish from PileInstallation, is studying the science behindaquatic pile driving and its impact on fish. Theproject team, led by Art Popper, University ofMaryland, has developed a wave tube appa-ratus to study the effects on fish in a labora-tory setting, using auditory signals that closelyreplicate those of pile driving. Variablesinclude the intensity of the pile-driving sig-nal, the number of strikes, and the intervalsbetween strikes. Postexposure experimentsassess the sample fish for hearing loss and tis-sue damage. Results of the study are expectedthis fall.

Air bubble curtainsubmerged and in action;the bubble curtain notonly reduces the sound,but also keeps fish awayfrom the pile.

Suggestions for “Research Pays Off” topics are wel-come. Contact G. P. Jayaprakash, TransportationResearch Board, Keck 488, 500 Fifth Street, NW,Washington, DC 20001 (telephone 202-334-2952,e-mail gjayaprakash@nas.edu).

Ken Courage has stacked up nearly five decades ofexperience in transportation, with more than 30years as a civil engineering professor at the Uni-versity of Florida (UF). After starting out as a traf-

fic signals engineer in Winnipeg, Canada, Courage has heldpositions in government, industry, and academia. His focusareas include transportation system modeling, highway capac-ity analysis, and traffic software development. Courage alsospecializes in the teaching and research aspects of advancedtraffic management systems, traffic data collection and analy-sis, and traffic safety. He has written many papers on the sub-ject of traffic management and control technology, and hasproduced a variety of traffic engineering software.

“I have enjoyed all aspects of this work,” he comments. “Ihope it’s been useful to someone!”

Courage joined the faculty of the UF Department of Civiland Coastal Engineering in 1971. Since his retirement in2003, he has served as an emeritus professor. “I look at retire-ment as the beginning of a new career in transportationresearch,” he remarks.

Courage became involved with the TransportationResearch Board in 1968 as principal investigator for NationalCooperative Highway Research Program (NCHRP) Project20-3. The project launched a landmark effort in freeway sys-tem management on the John Lodge Freeway in Detroit,Michigan. “That project was a bit ahead of its time,” headmits. “But it laid an important stone in the foundation ofwhat we now call intelligent transportation systems.”

In the 1990s he served as principal investigator for NCHRPProject 3-48, which developed an improved methodology fordealing with traffic-actuated control as described in the High-way Capacity Manual (HCM) chapter on signalized intersec-tion analysis. According to Courage, researchers “have pickedup where we left off. The result will be a greatly improved sig-nalized intersection analysis procedure in the 2010 HCM.”

Currently, Courage is principal investigator for NCHRPProject 3-85, Guidance for the Use of Alternative TrafficAnalysis Tools for Highway Capacity Analysis, and is a mem-ber of the NCHRP Project 3-92 team that is developing the2010 HCM. He also has been a member of the research teamfor three other NCHRP projects and has served on fourNCHRP project panels and two NCHRP synthesis panels.

“Traffic analysts often use simulation and other models inconjunction with, or instead of, the HCM procedures,” notesCourage. “Traffic simulation modeling is one of the most use-ful and productive developments of transportation research,but it will not make the HCM irrelevant. One of the mostimportant enhancements in the 2010 HCM will be the guid-

ance on how to use alternative toolseffectively.”

In addition to NCHRP, Couragehas been involved in many TRBstanding committees: the TrafficFlow Theory Committee, on whichhe currently serves; the HighwayCapacity and Quality of ServiceCommittee; the Traffic Signal Sys-tems Committee; and the FreewayOperations Committee. These fourcommittees sponsor the TRB JointTraffic Simulation Subcommittee, orSimSub, which Courage has chaired

for the past 5 years. “SimSub has come a long way in 5 years,”he observes. This year, he states, he plans to step down aschair “to make room for younger people with fresh ideas.”

Courage is a fellow of the Institute of Transportation Engi-neers (ITE), a past president of ITE’s Florida Section, and aregistered professional engineer. In 1972, Courage receivedthe Highway Research Board Award, and in 1973, the ITE PastPresidents Award. Other honors include a Traffic EngineeringCouncil Award from ITE, two Research Achievement Awardsfrom the University of Florida, and the ITE District 10 Sher-wood H. Hiller Distinguished Service Award. Last year, he wasinducted into the honor roll of the Intelligent TransportationSociety of Florida.

Courage graduated with a bachelor’s degree in electricalengineering from the University of Manitoba and received amaster’s degree in civil engineering from Texas A&M Uni-versity.

Courage notes that he has not missed an annual TRB meet-ing since the first one he attended in 1968. “That’s 42 in arow,” he points out. “Those meetings can tire you out, butthey are the most important transportation research event ofthe year. I always look forward to the next one.”TR

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P R O F I L E S. . . . . . . . . . . . . . . . . . .

“Traffic simulation modeling is one of

the most useful and productive

developments of transportation

research, but it will not make the

Highway Capacity Manual

irrelevant.”

Kenneth G. CourageUniversity of Florida

Robert D. (Bob) Holtz’s research in geotechnology andgeosynthetics has taken him around the globe. Pro-fessor of Civil Engineering at the University of Wash-ington (UW) in Seattle since 1988, he has held

engineering positions in such locales as Sweden, France, andItaly. Holtz, named professor emeritus at UW in 2008, citesgeosynthetics, foundations, soil reinforcing, soil improvement,and slope stability as his primary areas of research.

A native of Tucson, Arizona, Holtz earned bachelor’s andmaster’s degrees in civil engineering from the University of Min-nesota. In 1966, he attended Harvard University for a specialprogram in soil mechanics, and he received a Ph.D. in soilmechanics from Northwestern University in 1970.

Holtz began the academic side of his engineering career at theUniversity of Minnesota, Minneapolis, working as a teachingassistant while he earned his master’s degree. Since then—whilemaintaining an active consulting practice—Holtz has heldteaching and research positions at such institutions as Califor-nia State University; the Swedish Geotechnical Institute and theRoyal Institute of Technology, Stockholm, Sweden; NationalResearch Council of Canada, Ottawa; École Nationale des Pontset Chausseés, Paris; and Purdue University. His research spon-sors have included the National Science Foundation, the Pur-due Research Foundation, the Indiana Department of Highways,the Federal Highway Administration (FHWA), the United StatesAir Force, the Washington State Department of Transportation(DOT), the National Cooperative Highway Research Program,and several private companies.

Although he is now retired from full-time teaching andresearch, Holtz still oversees a research project of note to trans-portation geotechnical engineers.

“We are constructing a very steep slope reinforced by ‘Spi-ralnails’ that is well instrumented and will be loaded to failureby a large footing-and-jack system on the top of the stabilizedslope,” Holtz explains. Spiralnails are a new type of groutless soilnailing system developed by a Seattle-area engineer, and the

project is funded by Hilfiker Retaining Walls. A recently com-pleted project involved a full-scale instrumented field test offootings constructed on several short, compacted aggregate piersat a stiff clay site in Texas.

Research is a foundation of a professor’s life, Holtz notes. “Itis gratifying to see that some of our research on geosyntheticshas been put to good use by highway agencies, such as IndianaDOT and, especially, Washington State DOT,” he observes. “Forexample, our research on geotextile separators shows that theyreally do work.” Holtz adds that findings on soil reinforcing withgeosynthetics have influenced the development of a new designapproach for geosynthetic reinforced retaining walls and slopes.

Holtz expresses concern, however, about the future of geo -technical research related to transporta-tion. Organizations such as FHWA andWashington State DOT recently havemuch less funding for geotechnicalresearch, he notes: “Unfortunately,many problems remain, and they areunlikely to be solved without some typeof a directed and collaborative appliedresearch program between the profes-sional geotechnical engineers in thetransportation agencies and the univer-sities.”

Holtz’s TRB activities draw on hisgeotechnical research expertise. He has

been a member of the Design and Construction Group, and ofthe Committees on Geosynthetics, Soils, and Rock Instrumen-tation, and Soil and Rock Properties. He also contributed hisexpertise to the Transportation Earthworks committee for nearly20 years, serving as chair from 1982 to 1988. Holtz also chairedthe Geology and Properties of Earth Materials Section(1990–1996). In 1999, he was named an emeritus member ofthe Soil and Rock Properties Committee.

Holtz is working to finish the second edition of the under-graduate textbook, An Introduction to Geotechnical Engineering,which he coauthored with Bill Kovacs in 1981. Now in its 42ndprinting, the book has been translated into Chinese, BahasaMalaysian, French, and Turkish. Holtz also coauthored theFHWA Geotextile Engineering Manual with Barry R. Christopher(1985), and Geosynthetic Engineering with Ryan R. Berg andChristopher (1997), and has authored or contributed to manychapters, journal articles, papers, and other publications.

Several awards and honors have recognized Holtz’s contri-butions to the field of geotechnical research, including Distin-guished Member of the American Society of Chemical Engineers(ASCE), Cross-Canada Lecturer for the Canadian GeotechnicalSociety, Puget Sound Academic Engineer of the Year, and the IGSPioneer Award from the International Geosynthetics Society.

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P R O F I L E S. . . . . . . . . . . . . . . . . . .

“It is gratifying to see that some of

our research on geosynthetics has

been put to good use by highway

agencies, such as Indiana DOT and,

especially, Washington State DOT.”

Robert D. HoltzUniversity of Washington

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Sensor May Adjust Spring LoadRestrictionsResearchers at Case Western Reserve University,Cleveland, Ohio, are testing a new sensor to moni-tor the freeze–thaw status of subsurface pavementconditions. Led by Xiong (Bill) Yu, the team hopesthat their research into pavement strength with thesensor will shave some time off the mandatory springload restrictions (SLR), or vehicle weight limits, thatare in place throughout the winter in cold regions.SLR is a pavement preservation strategy in theseregions, designed to prevent deterioration of thepavement substructure during the spring thaw,which saturates and weakens pavement layers.

Tested at MnROAD, the outdoor roadway labora-tory in Ostego, Minnesota, the sensor is “rugged,sensitive, and portable,” according to Yu, and hasdistributive sensing capability on moisture migra-tion. Its performance since October 2007 has demon-strated excellent signal quality, he reports.

Jurisdictions in the United States currently setload restrictions based mainly on deflection mea-surement and experience. To simplify the decision of

when to start the restrictions, the Minnesota Depart-ment of Transportation (DOT) uses the actual andpredicted average daily temperature, with the SLRduration fixed at 8 weeks. Restrictions must beplaced when the pavement first thaws and the stiff-ness of the base layer is low; proper measurementand prediction of freeze-thaw events is crucial to asuccessful load-restriction strategy. Although a fewtechnologies can provide such information—forexample, temperature-based technologies and resis-tivity probes—they are not reliable and the data col-lection is time-consuming, Yu notes.

In 2008, the sensor indicated that the ground wasrelatively stable between February 15 and 29, with anappreciable amount of thaw between February 29and March 14. The trend of change was more signif-icant between March 14 and 29, according to thedata. After that, the ground moisture continued toincrease slightly and was relatively stable from April15 to July 15, when the most current data were ana-lyzed. According to Yu, this implies that the SLRcould have been lifted around April 15, 2008. Therestrictions were not lifted in most areas of Min-nesota until May 13, 2008.

Although the results are encouraging, theresearchers are working on validation of the sensorat different locations and with alternative designs—such as hot-mix asphalt thickness, base types, con-struction variations, and others—to provide betterdecision support. The MnRoad research team—ledby Ben Worel, with members Jack Herndon, RobertStrommen, and Doug Lindenfelser—is a collaboratorin the study.

For more information, contact Bill Yu, 216-368-6247, xxy21@case.edu.

NEWS BRIEFSA new sensor,currently being testedto monitorfreeze–thaw status ofsubsurface pavementconditions, is placedbeneath thepavement surface.

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Seatbelt Use Up,Traffic Fatalities DownTwo reports released by the National Highway Traf-fic Safety Administration (NHTSA) show a rise inseat belt use and a decline in motor vehicle trafficfatalities for 2008. According to the reports, NHTSA’sNational Occupant Protection Use Survey measureda nationwide 83 percent rate of seat belt use last year,and traffic fatalities fell from 41,059 in 2007 to aprojected total of 37,313 in 2008.

Sixteen states and territories had use rates of 90percent or higher, according to the NHTSA report. Ingeneral, areas with stronger seat belt enforcementlaws had higher use rates. According to state andterritory surveys, Michigan had the highest rate ofseat belt use—97.2 percent—and American Samoa,with 55.7 percent, had the lowest. Nineteen stateshad less seat belt use in 2008 than in 2007, withRhode Island’s use rate dropping 7.1 percent. Of the35 states and territories that showed an increase inseat belt use, the highest were the Northern MarianaIslands, with an increase of 9.8 percent, and NewYork, with an increase of 5.6 percent.

NHTSA’s early estimate of motor vehicle trafficfatalities in 2008 shows a 9.1 percent decline fromfatalities reported in 2007. An actual count of lastyear’s traffic fatalities will be released in August. Theestimated decline, based on a statistical projection,would be the third-largest drop in traffic fatalitiessince 1961. Preliminary data from the Federal High-way Administration show that vehicle miles traveled(VMT) also fell in 2008, to 2,922 billion miles—anapproximate 3.6 percent drop. The fatality rate, com-puted per 100 million VMT, declined from 1.36 in2007 to 1.28 in 2008.

N E W S B R I E F S

An international agency initiative endeavors toreduce by half automobile greenhouse gas emis-sions in the European Union by 2050. The 50 by 50Global Fuel Economy Initiative (GFEI) report,issued in March, promises to achieve a savings of 6billion barrels of oil and to prevent the release of 2gigatons of carbon dioxide annually.

According to the report, GFEI would accom-plish its goal by helping and supporting policiesto promote the production of more fuel-efficientvehicles.

The path to a 50 percent reduction in fuel con-sumption per kilometer takes into account sugges-tions made by the Intergovernmental Panel onClimate Change, and would entail collaborationwith governments as well as the car industry. GFEI’s

objectives for 2009 include regional assessmentsand launches to further political involvement inEurope, North America, Latin America, and Asia;four regional pilot projects to aid the developmentof national fuel economy policies; interaction withthe Group of Eight (G8) forum and the UnitedNations (UN); and the formulation of a fuel econ-omy information database, information materials,and website.

GFEI is a result of the partnership between theUN Environment Programme, the InternationalEnergy Agency, the International Transport Forum,and Fédération Internationale de l’AutomobileFoundation.

For more information, visit www.50by50campaign.org.

Women’s Transportation Seminar (WTS) hasexpanded its scholarship program, creating the WTSFoundation, a 501(c)(3) organization that supportsthe advancement of women in transportation pro-fessions. The WTS Foundation replaces the WTSScholarship, which has raised $2,000,000 and dis-bursed more than $900,000 in its 15 years. The foun-dation plans to initiate, sponsor, and publish research

and to promote and offer education opportunitiesand professional development for women in thetransportation community.

In 2008, TRB Executive Director Robert E. Skin-ner, Jr., signed a memorandum of understandingwith WTS Past President Ann L. Koby as part ofTRB’s concerted effort to encourage the involvementof women in transportation.

Women’s Group Expands Scholarship Program

Many states, likePennsylvania,participate in anational seat beltuse enforcementand educationcampaign.

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A COMMITMENT TO SCIENCE AND TECH-NOLOGY—President Barack Obamaannounced new initiatives and invest-ments in science at the 146th Annual Meeting of the National Academy of Sci-ences (NAS), Monday, April 28, at theNAS Building in Washington, D.C. Aftera welcome by NAS President Ralph J.Cicerone, Obama discussed his adminis-tration’s commitment to scientificprogress and promised to devote 3 per-cent of the country’s gross domestic product to funds for scientific researchand innovations. The budgets of threeagencies—the National Science Founda-tion, the Department of Energy’s Officeof Science, and the National Institute ofStandards and Technology—will be dou-bled, Obama said. He also announcedthe members of the President’s Councilof Advisors on Science and Technology—seven are NAS members.

TRB HIGHLIGHTS

Developing Reliability-BasedBridge Inspection PoliciesThe National Bridge Inspection Standards (NBIS), whichmandate the frequency and methods used for the safetyinspection of highway bridges, require routine inspectionsevery 24 months. That interval may be extended to 4 yearsfor bridges that meet certain criteria and are approved bythe Federal Highway Administration, but under NBIS,hands-on inspections are required every 2 years for bridgeswith fracture-critical elements.

In general, the inspection intervals are not based on theperformance of bridge materials or designs but derive fromexperience managing the 600,000 bridges in the NationalBridge Inventory. Although applied to the entire bridgeinventory, these inspection intervals may not be appro-priate for all bridges; for example, recently constructedbridges typically experience few problems during theirfirst decade of service, but under the requirements, thesebridges must have the same inspection frequency andintensity as a 50-year-old bridge nearing the end of its ser-vice life. The application of reliability theory to inspectionpractices can help meet the goals of improving bridgesafety and reliability, as well as optimize resources forbridge inspection.

The University of Missouri has been awarded a$399,930, 20-month contract [National CooperativeHighway Research Program (NCHRP) 12-82, FY 2009] tohelp develop a recommended bridge inspection practicefor consideration by the American Association of State

Highway and Transportation Officials (AASHTO). Theproject is scheduled for completion in December 2010.

For more information, contact Waseem Dekelbab, TRB,202-334-4109, wdekelbab@nas.edu.

Calibrating Concrete Bridge DesignSpecifications for ServiceabilityAASHTO’s LRFD (Load and Resistance Factor Design)Bridge Design Specifications has its primary advantage inuniform reliability at the strength limit state, achieved bystatistical calibration. Service and fatigue limit states, how-ever, can only be calibrated using engineering judgment.This process does not achieve uniform reliability. Althoughthis research project focuses on concrete bridges, the lackof reliability for service and fatigue limit states also affectssteel bridges.

To assure that uniform reliability is achieved for all limitstates, the calibration will include criteria for cracking,deformation, and concrete stresses, along with the newlyadopted fatigue provisions. Additional limit states mayneed to be added and calibrated to include other effects,such as owner-specified design and permit vehicles.

A $500,000, 30-month contract [NCHRP Project 12-83, FY 2009] has been awarded to Modjeski & Masters,Inc., to develop new concrete service and fatigue limitstates as needed, to calibrate new and existing concrete ser-vice and fatigue limit states, and to prepare specificationsfor consideration by the AASHTO Highway Subcommit-tee on Bridges and Structures. The project is scheduled for

COOPERATIVE RESEARCH PROGRAMS NEWS

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ADVANCING EQUITY CONSIDERATIONS—Brian Taylor, UCLA (left); Jef-frey Buxbaum, Cambridge Systematics; T. Keith Lawton, Keith LawtonConsulting, Inc.; Johanna Zmud, NuStats, LLC; and David Levinson, Uni-versity of Minnesota, participate in a meeting of the Committee onEquity Implications of Alternative Transportation Finance Mechanisms.The committee convened May 7 and 8 at the Keck Center to explorethe equity implications of alternative funding mechanisms for trans-portation projects. The committee also is working to pinpoint specificissues to consider when alternative transportation funding mecha-nisms are proposed and to develop recommendations for research.

L E A R N I N G F R O MI N T E R N A T I O N A LB E N C H M A R K S —The Committee for theStudy of Traffic SafetyLessons from BenchmarkNations—including (leftto right) Alison Smiley,Human Factors North,Inc.; Anthony G. Bliss,World Bank; and consul-tant Allan F. Williams—met April 21 at theNational Academies’ KeckCenter, Washington, D.C.The committee is investi-gating successful safetyprograms in nations suchas Sweden, United King-dom, Netherlands, andAustralia, as models toadapt and apply in reducing traffic deaths and injuries in the UnitedStates. A main focus of the study is an examination of the approachesused to build public and political support for the programs.

completion in October 2011.For more information, contact Waseem Dekelbab, TRB,

202-334-4109, wdekelbab@nas.edu.

Guidelines for PerformanceMeasurement of Congestion PricingAs demand for highway facilities increases and capacityremains limited, highway traffic congestion—one of thebiggest challenges facing transportation agencies today—will likely continue to worsen. Increasing peak times, lossof productivity during congested periods, and underuti-lization of capacity during off-peak periods are some of thesystem management challenges faced by the industry.

A growing momentum within government transporta-tion agencies to explore congestion pricing and evaluateits performance means that transportation organizationsneed assistance in developing and tracking measurementsto assess the benefits and impacts of congestion pricingstrategies. More knowledge is needed on how to developappropriate performance measurements, data tracking andanalysis methods, and ways to communicate the results tothe public.

PB Americas has been awarded a $200,000, 18-monthcontract [NCHRP Project 08-75, FY 2009] to create guide-lines for evaluation and performance measurement of con-gestion pricing projects to optimize the use of roadwaycapacity. The guidelines will help agencies select ordevelop appropriate performance measures, collect thenecessary data, track performance, and communicate the

results to decision makers, users, and the general pub-lic. The scheduled completion date for this project isNovember 1, 2010.

For further information, contact Chris Hedges, TRB, 202-334-1472, chedges@nas.edu.

Identification and Evaluationof Freight Demand FactorsHistorically, forecasts of demand for freight transportationhave underestimated substantially the growth in freightvolumes and average lengths of haul. As a result, today’shighways are overwhelmed with trucks, rail capacity islacking because of abandonments, and transportationinfrastructure sizing and pricing face planning dilemmas.

More recent national freight forecasts predict enormousincreases in the demand for freight transportation in thenext two decades. Because of the underestimation offreight demand by forecasters in the past, however, it is notcertain whether these predictions of freight growth areany more accurate.

The research firm Halcrow has been awarded a$350,000 contract [National Cooperative Freight ResearchProgram (NCFRP) Project 11, FY 2009] to describe andanalyze factors that may contribute to future freight quan-tity; geographic distribution; temporal distribution of tons,ton miles, vehicle miles, or train miles; and the value offreight to be moved in and through North America.

For further information, contact Bill Rogers, 202-334-1621, wrogers@nas.edu.

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TRB Meetings

C A L E N D A R

Additional information on TRB meetings, including calls for abstracts, meeting registration, and hotel reservations, is available atwww.TRB.org/calendar. To reach the TRB staff contacts, telephone 202-334-2934, fax 202-334-2003, or e-mail lkarson@nas.edu.Meetings listed without a TRB staff contact have direct links from the TRB calendar web page.

*TRB is cosponsor of the meeting.

2009

July

19–22 48th Annual Workshop onTransportation LawDenver, Colorado

19–22 2009 TRB Joint SummerConferenceSeattle, Washington

19–23 12th AASHTO–TRBMaintenance ManagementConference*Annapolis, Maryland

22 Northwest Traffic DataWorkshopSeattle, Washington

28–29 2009 TransportationPlanning, Land Use, and AirQuality ConferenceAmes, Iowa

August

3–6 GeoHunan: Challenges andRecent Advances in PavementTechnologies andTransportation Geotechnics*Hunan, China

17–18 5th New York City BridgeConference*Battery Park, New York

24–27 Transportation Hazards andSecurity Summit 2009:Progress Through Partnership(by invitation)Irvine, California

29– 14th Conference on ColdSept. 2 Regions Engineering*

Duluth, Minnesota

September

6–9 4th International Congress ofSmart Rivers 21: The Futureof Inland Navigation*Vienna, Austria

14–15 Integrated Corridor SystemManagement Modeling BestPractices WorkshopIrvine, California

16–17 North American Freight FlowsConference 2009Irvine, California

17–18 Research on the Transmissionof Disease in Airports and onAircraft: A SymposiumWashington, D.C.

28 Long-Term Performance ofGeotechnical InfrastructureBuffalo, New YorkG. P. Jayaprakash

October

5–7 European TransportConference*Leiden, Netherlands

13–14 Infrastructure SecurityWorkshop*Rutgers, New JerseyJoedy Cambridge

19–22 8th National Conference onAsset ManagementPortland, Oregon

27–30 4th International Conferenceon Women’s Issues inTransportationIrvine, California

29 EMS (Emergency MedicalServices) Workshop andMidyear MeetingWashington, D.C.Richard Pain

November

12–13 Developing a ResearchAgenda for TransportationInfrastructure Preservationand RenewalWashington, D.C.

December

13–18 12th InternationalConference on TravelBehavior Research*Jaipur, IndiaKimberly Fisher

2010

January

10–14 TRB 89th Annual MeetingWashington, D.C.

April

12–16 1st International Conferenceon Pavement Preservation*Newport Beach, California

May

5–7 1st International Conferenceon Nanotechnology inCement and ConcreteIrvine, California

30– Safety and Mobility ofJune 2 Vulnerable Road Users:

Pedestrians, Motorcyclists,and Bicyclists*Jerusalem, IsraelRichard Pain

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On Being a Scientist: A Guide to ResponsibleConduct in Research, Third EditionThe National Academies Press,2009; 82 pp.; $11.65; 978-0-309-11970-2.The National Research Councilhas released the third edition ofOn Being a Scientist, a report on the practice of sci-ence that applies to all forms of research—whetherin academic, industrial, or governmental settings—and to all scientific disciplines. The report, designedto supplement informal ethics lessons provided byresearch supervisors and mentors, describes the eth-ical foundations of scientific practices, along withsome of the personal and professional issues thatresearchers encounter in their work.

The third edition reflects developments since thepublication of the original edition, in 1989, and a sec-ond edition, in 1995. It includes a number of hypo-thetical scenarios and offers guidance in thinkingabout and discussing these scenarios. Among thetopics addressed are the responsibilities of advisersand their advisees, appropriate ways to share researchresults, the treatment of people and animals involvedin studies, and mistakes and negligence in research.Also included is a list of books and articles for fur-ther reading.

The St. Lawrence Seaway andPower Project: An OralHistory of the GreatestConstruction Show on EarthClaire Puccia Parham. SyracuseUniversity Press, 2009; 328 pp.;$34.95; 978-0-8156-0913-1In time for the 50th anniversaryof the St. Lawrence Seaway andPower Project, a 265-mile-long canal separatingAmerica from Canada, a new book reveals the proj-ect’s human side in the words of 53 engineers, car-penters, laborers, and their wives. Author ClairePuccia Parham exposes the dangerous working con-ditions, larger-than-life equipment, and constructiondilemmas encountered by workers.

The project, which began in 1954 and was com-pleted in 1959, cost $1 billion and is one of thelargest public works initiatives of the 20th century.The largest waterway and hydro dam project everjointly built by two nations, the Seaway project com-prised seven locks, the widening of various canals,the taming of rapids, and the erection of the 3,216-foot-long, 195.5-foot-high Robert Moses–Robert H.Saunders Power Dam. Since its completion, the Sea-way has seen the transport of 2.5 billion tons ofcargo—equivalent to 87 million truckloads—valuedat more than $375 billion. It also produces hydro-electric power for Canada and the United States.

BOOKSHELF

TRB PUBLICATIONS

The books in thissection are not TRBpublications. Toorder, contact thepublisher listed.

U.S. Marine Salvage Assets and Capabilities in a Maritime DisasterTRB Conference Proceedings 45This report contains the proceedings of a September2008 workshop focusing on a scenario of an incidentthat shuts down the Ports of Los Angeles and LongBeach. The proceedings examine the threat andexplore key issues relating to an efficient, effective,and coordinated U.S. salvage industry response to aworst-case marine casualty scenario.

2009; 81 pp.; TRB affiliates, $36; nonaffiliates, $48.Subscriber categories: marine transportation (IX) andsecurity (X).

Components of Bituminous Paving Mixtures 2008Transportation Research Record 2051 Presented are findings on polyphosphoricacid–modified asphalts, biofuel coproducts for per-formance enhancement of asphalt binders, fieldaging of unmodified asphalt binder, and asphaltmixes containing expanded clay aggregate. Other

topics explored include the effects of mineral filler,hot-mix asphalt containing hydrated lime, stonematrix asphalt mixtures with reclaimed asphalt pave-ment, and the incorporation of reclaimed asphaltpavement in warm-mix asphalt.

2008; 97 pp.; TRB affiliates, $40.50; nonaffiliates,$54. Subscriber category: materials and construction(IIIB).

Aviation 2008Transportation Research Record 2052 An evaluation of airline service quality; a forecast of airtaxi, commercial airline, and automobile demand inthe United States; a comparison of low-cost and full-service carriers in Southeast Asia; the cost of U.S. avi-ation infrastructure; short-haul airline crew rostering;segmentation and positioning analysis for the inter-national air travel market; and airport taxi–out pre-diction are some of the topics explored in this volume.

2008; 125 pp.; TRB affiliates, $41.25; nonaffiliates,$55. Subscriber category: aviation (V).

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Geology and Properties of Earth Materials 2008Transportation Research Record 2053The papers in this volume explore topics such asfrost and thaw depth predictors for variable loadrestrictions, climate-change impact on low-volumeroads, fly ash with calcium chloride for stabilizationof base and subgrade courses, field and laboratorysuction measurements of expansive clays, comput-

erized cone penetration tests for soil classification,and correlation between resilient modulus and plas-tic deformation for cohesive subgrade soil underrepeated loading.

2008; 79 pp.; TRB affiliates, $39; nonaffiliates, $52.Subscriber category: soils, geology, and foundations(IIIA).

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TRB PUBLICATIONS (continued)

The Last Steam Railroad in AmericaThomas Garver and O. Winston Link. Abrams, 1995; 144 pp.;$35; 978-0-8109-8201-7.

The era of the steam railroad was evoked in an exhibitionof fascinating historical photographs by O. Winston Link at

the National Academy of Sciences (NAS) building in Washing-ton, D.C., March 11–June 15. Taken from 1955 to 1959 alongthe Norfolk and Western Railway, Link’s photographs provideda revealing glimpse into the past. On May 20, Thomas Garver,Link’s photographic assistant and author of The Last SteamRailroad in America (1995, Abrams), delivered a lecture on thephotographs at the National Academies’ Keck Center in con-junction with the NAS exhibition.

Link’s assistant from 1957 to 1958, Garver participated inthree trips along the Norfolk and Western Railway to recordthe trains in photographs and audio. “Winston was fascinatedby the technology of [trains],” Garver said.

Garver believes that Link’s interest in rail started in child-hood. The Brooklyn-born Link had a standard-gauge Lioneltrain set growing up, said Garver, and Link spent time as ateenager taking pictures of the Erie Railroad and the luxuryBlue Comet train in New Jersey. The fascination continued intoadulthood, and while on a commissioned advertising photog-raphy project in Northern Virginia in 1955, Link saw a Norfolkand Western train pulling into the station. He returned to pho-tograph it the following night, and conceived of a project tophotograph the trains as they traveled through the mountainsof West Virginia, North Carolina, and Virginia, and to captureimages of the people and places that trains served.

“People in Virginia and North Carolina and West Virginiawere very supportive of [the project]; they really showed himSouthern hospitality,” said Garver.

Trained as a commercial photographer to produce picturesthat told a story and evoked a certain response, Link set up hisphotographs carefully, controlling every aspect of lighting,scene, and subject placement. He even acquired keys to the dis-patcher’s signal boxes so that he could tell conductors to speedor slow the trains in advance of the shot, said Garver.

Most of Link’s photographs were taken at night, which

allowed him to manipulate the lighting and bring a “humanvitality” to images of rail. “He created photographs that drewpeople in,” said Garver. “Even people who couldn’t imaginethemselves interested in those ‘greasy old machines.’”

According to Garver, Link’s photographs evoke the connec-tion between trains and “the good life.” Scenes such as a youngcouple at a drive-in movie with a train in the background, or afather and son bringing home a Christmas tree as a train passesby, suggest that the American experience is provided by, or atleast supported by, the railroad system. Link took up the proj-ect on his own, said Garver; Norfolk and Western did not com-mission or pay for it but encouraged and accommodated Linkin his mission.

In 1994, after a career as an art museum director, writer, andindependent curator, Garver became Link’s business agent. Heassisted on Link’s first book, Steam, Steel & Stars (1987, Abrams)and in 1995 wrote The Last Steam Railroad in America. AfterLink’s death in 2001, Garver served as organizing curator of theO. Winston Link Museum, located in the former Norfolk andWestern Railway passenger station in Roanoke, Virginia.

For more information on the O. Winston Link Museum, visitwww.linkmuseum.org. For listings of National Academies’ cul-tural programs, visit national-academies.org.

—Lea Mae Rice

Thomas Garver with O. Winston Link’s 1956 photograph, “HotshotEastbound at the Iaeger Drive-In, Iaeger, West Virginia.”

Trains That Passed in the NightAuthor Offers Insights on Photo Exhibit

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Activity and Time Use Analysis 2008Transportation Research Record 2054Authors investigate synchronicity of activity engage-ment and travel, analysis of activity conflict resolu-tion strategies, destination choice in daily activitytravel, differences of household weekday and week-end activities, analysis of planning decisions duringthe activity-scheduling process, weekly rhythm injoint time expenditure for at-home and out-of-homeactivities, a random utility-based microeconomicmodel for discretionary activity time allocation, net-work equilibrium with activity-based microsimula-tion models, and other topics.

2008; 109 pp.; TRB affiliates, $41.25; nonaffiliates,$55. Subscriber category: planning and administration(IA).

Work Zones and Maintenance OperationsTransportation Research Record 2055The 16 papers in this volume examine late lanemerges, automated speed photo enforcement, sched-uling, traffic delay, high-mast lighting, retroreflectiv-ity of pavement markings, asset managementpractices for pavement markings, surface trans-portation weather, and aspects of winter mainte-nance.

2008; 146 pp.; TRB affiliates, $48; nonaffiliates,$64. Subscriber category: maintenance (IIIC).

Traffic Control Devices, Visibility, andHighway–Rail Grade Crossings 2008Transportation Research Record 2056Glare, pedestrian visibility in crosswalks, pavementmarking retroreflectivity, “stop ahead” pavementmarkings, modern pavement marking systems, nine-panel logo signs, treatments at urban signalized inter-sections, dual-advisory speed signing onfreeway-to-freeway connectors, and gate rushing athighway–railroad grade crossings are some of thetopics covered in this volume.

2008; 109 pp.; TRB affiliates, $41.25; nonaffiliates,$55. Subscriber category: highway operations, capac-ity, and traffic control (IVA).

Environment and Energy 2008Transportation Research Record 2058 Presented are findings on the Tennessee Environmen-tal Procedures Manual, infrastructure strategies toreduce emissions from intermodal freight movementin Southern California, B20 biodiesel emissions com-pared against petroleum diesel emissions, emissionbehavior of public transportation buses with alter-native diesel fuels, environmental impacts of cat-alytic converter malfunctions, a wildlife habitatclassification to improve transportation and conser-

vation planning, environmental assessment oftire–pavement noise, carbon dioxide impacts of traf-fic congestion, and more.

2008; 178 pp.; TRB affiliates, $51; nonaffiliates,$68. Subscriber category: energy and environment (IB).

Geomaterials 2008Transportation Research Record 2059Authors study the Micro-Deval test for coarse aggre-gates and fine aggregates, anisotropic behavior ofaggregate bases, permanent deformation of naturalbituminous sands, stiffness of unbound aggregatebases, shear strength of recycled glass, the perfor-mance of chemically modified subgrade soils, ruttingof cement-treated base material, physicochemicalbehavior of cement kiln dust-treated kaolinite clay,lime in full-depth reclamation, and cement- andfiber-stabilized soil rapid assessment.

2008; 102 pp.; TRB affiliates, $40.50; nonaffiliates,$54. Subscriber category: soils, geology, and founda-tions (IIIA).

Highway Design 2008Transportation Research Record 2060The 18 papers in this volume explore topics in geo-metric design; roadside safety design in grates,guardrails, and cable barriers; landscape and envi-ronmental design; context-sensitive design and solu-tions; hydrology, hydraulics, and water quality; andutilities.

2008; 172 pp.; TRB affiliates, $51; nonaffiliates, $68.Subscriber category: highway and facility design (IIA).

Statistical MethodsTransportation Research Record 2061An analysis of naturalistic driving data, adjustmentfor a maximum likelihood estimate of negative bino-mial dispersion parameter, nonparametric Bayesianestimation of freeway capacity distribution, and tree-based regression models are some of the paper top-ics in this volume. Also examined are crashfrequency analysis with generalized additive modelsand spatial models, estimation of confidence inter-vals of crash prediction models, and cross-correlationanalysis and multivariate prediction of spatial timeseries of freeway traffic speeds.

2008; 76 pp.; TRB affiliates, $39; nonaffiliates, $52.Subscriber categories: planning and administration(IA), and safety and human performance (IVB).

Effectiveness of Behavioral Highway SafetyCountermeasuresNCHRP Report 622A framework to assess the costs and benefits ofemerging, experimental, untried, or unproven behav-

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ioral highway safety countermeasures is explored inthis report, along with guidance for estimating theeffectiveness of these countermeasures.

2008; 50 pp.; TRB affiliates, $30; nonaffiliates, $40.Subscriber category: safety and human performance(IVB).

Identifying and Quantifying Rates of State MotorFuel Tax EvasionNCHRP Report 623The findings in this report initiate an exploration ofa methodological approach to examine and quantifystate motor fuel tax evasion rates and to supportagency efforts to reduce differences between totalfuel tax liability and actual tax collections.

2008; 180 pp.; TRB affiliates, $43.50; nonaffiliates,$58. Subscriber category: planning and administration(IA).

Selection and Application of Warning Lights onRoadway Operations EquipmentNCHRP Report 624Recommended guidelines for the selection and appli-cation of warning lights on roadway operationsequipment address physical, functional, and perfor-mance requirements of the lighting system; recognizethat the lighting system must be designed and laidout with consideration to planned vehicle usage; andprovide technical information to develop procure-ment specifications for specific applications.

2008; 40 pp.; TRB affiliates, $27.75; nonaffiliates,$37. Subscriber categories: maintenance (IIIC), safetyand human performance (IVB).

Traffic Safety Evaluation of Nighttime andDaytime Work Zones NCHRP Report 627Investigated in this report are crash rates for night-time and daytime work zones, and managementpractices that promote safety and mobility in workzones. The report also features work-zone crashreporting suggestions, designed to help improve thedata collected on these crashes.

2008; 78 pp.; TRB affiliates, $35.25; nonaffiliates,$47. Subscriber category: safety and human perfor-mance (IVB).

Self-Consolidating Concrete for Precast,Prestressed Concrete Bridge ElementsNCHRP Report 628Strategies for the use of self-consolidating concrete(SCC) in precast, prestressed concrete bridge ele-ments; the selection of constituent materials; pro-portioning of concrete mixtures; testing methods;fresh and hardened concrete properties; production

and quality control issues; and other aspects of SCCare some of the issues examined in this volume.

2009; 92 pp.; TRB affiliates, $37.50; nonaffiliates,$50. Subscriber categories: bridges, other structures,and hydraulics and hydrology (IIC); and materials andconstruction (IIIB).

Performance-Based Construction ContractorPrequalificationNCHRP Synthesis 390This report summarizes the experience of state trans-portation agencies that have examined contractors’ pastperformance as part of the prequalification process.Focusing on design–bid–build projects, this synthesisalso examines information on the process developed inother sectors of the construction industry.

2009; 101 pp.; TRB affiliates, $38.25; nonaffiliates,$51. Subscriber categories: planning and administra-tion (IA) and materials and construction (IIIB).

Shared Use of Railroad Infrastructure withNoncompliant Public Transit Rail Vehicles: A Practitioner’s GuideTCRP Report 130Studied is a business case for the shared use of pub-lic transit rail vehicles that do not comply with Fed-eral Railroad Administration regulations, such aslight rail vehicles, with freight operations. The reportalso highlights a business model for shared-use oper-ations and explores the potential advantages and dis-advantages of these operations.

2009; 109 pp.; TRB affiliates, $39; nonaffiliates,$52. Subscriber categories: public transit (VI) and rail(VII).

Transit Systems in College and UniversityCommunitiesTCRP Synthesis 78An update of an earlier synthesis, this volumeexplores practices and trends in the areas of campustransit operations, policies, and planning, with afocus on technological and environmental innova-tions; as well as innovative partnership strategies toenhance services.

2008; 88 pp.; TRB affiliates, $35.25; nonaffiliates,$47. Subscriber category: public transit (VI).

To order TRB titlesdescribed in Bookshelf,visit the TRB onlineBookstore, at www.TRB.org/bookstore/, or contact the BusinessOffice at 202-334-3213.

TRB PUBLICATIONS (continued)

The TRR Journal Online website provides electronicaccess to the full text of more than 9,000 peer-reviewedpapers that have been published as part of theTransportation Research Record: Journal of the Trans-portation Research Board (TRR Journal) series since1996. The site includes the latest in search technologiesand is updated as new TRR Journal papers become available. To explore the TRR Online service, visitwww.TRB.org/TRROnline.

TR News welcomes the submission of manuscripts for possiblepublication in the categories listed below. All manuscripts sub-mitted are subject to review by the Editorial Board and otherreviewers to determine suitability for TR News; authors will beadvised of acceptance of articles with or without revision. Allmanuscripts accepted for publication are subject to editing forconciseness and appropriate language and style. Authorsreceive a copy of the edited manuscript for review. Original art-work is returned only on request.

FEATURES are timely articles of interest to transportation pro-fessionals, including administrators, planners, researchers, andpractitioners in government, academia, and industry. Articlesare encouraged on innovations and state-of-the-art practicespertaining to transportation research and development in allmodes (highways and bridges, public transit, aviation, rail, andothers, such as pipelines, bicycles, pedestrians, etc.) and in allsubject areas (planning and administration, design, materialsand construction, facility maintenance, traffic control, safety,geology, law, environmental concerns, energy, etc.). Manuscriptsshould be no longer than 3,000 to 4,000 words (12 to 16 double-spaced, typed pages). Authors also should provideappropriate and professionally drawn line drawings, charts, ortables, and glossy, black-and-white, high-quality photographswith corresponding captions. Prospective authors are encour-aged to submit a summary or outline of a proposed article forpreliminary review.

RESEARCH PAYS OFF highlights research projects, studies,demonstrations, and improved methods or processes that provide innovative, cost-effective solutions to importantt rans portation-related problems in all modes, whether theypertain to improved transport of people and goods or provi-sion of better facilities and equipment that permits such trans-port. Articles should describe cases in which the applicationof project findings has resulted in benefits to transportationagencies or to the public, or in which substantial benefits areexpected. Articles (approximately 750 to 1,000 words) shoulddelineate the problem, research, and benefits, and be accom-panied by one or two illustrations that may improve a reader’sunderstanding of the article.

NEWS BRIEFS are short (100- to 750-word) items of inter-est and usually are not attributed to an author. They may beeither text or photographs or a combination of both. Linedrawings, charts, or tables may be used where appropriate.Articles may be related to construction, administration, plan-ning, design, operations, maintenance, research, legal matters,or applications of special interest. Articles involving brandnames or names of manufacturers may be determined to beinappropriate; however, no endorsement by TRB is impliedwhen such information appears. Foreign news articles shoulddescribe projects or methods that have universal instead oflocal application.

POINT OF VIEW is an occasional series of authored opin-ions on current transportation issues. Articles (1,000 to2,000 words) may be submitted with appropriate, high-qual-ity illustrations, and are subject to review and editing. Read-ers are also invited to submit comments on published pointsof view.

CALENDAR covers (a) TRB-sponsored conferences, work-shops, and symposia, and (b) functions sponsored by otheragencies of interest to readers. Notices of meetings shouldbe submitted at least 4 to 6 months before the event.

BOOKSHELF announces publications in the transportationfield. Abstracts (100 to 200 words) should include title, author,publisher, address at which publication may be obtained, num-ber of pages, price, and ISBN. Publishers are invited to submitcopies of new publications for announcement.

LETTERS provide readers with the opportunity to com-ment on the information and views expressed in publishedarticles, TRB activities, or transportation matters in gen eral.All letters must be signed and contain constructive comments. Letters may be edited for style and space considerations.

SUBMISSION REQUIREMENTS: Manuscripts submittedfor possible publication in TR News and any correspondenceon editorial matters should be sent to the Director, Publica-tions Office, Transportation Research Board, 500 Fifth Street,NW, Was hington, DC 20001, telephone 202-334-2972, or e-mail jawan@nas.edu.

� All manuscripts should be supplied in 12-point type,double-spaced, in Microsoft Word 6.0 or WordPerfect 6.1 orhigher versions, on a diskette or as an e-mail attachment.

� Submit original artwork if possible. Glossy, high-qual-ity black-and-white photo graphs, color photographs, andslides are acceptable. Digital continuous -tone images mustbe submitted as TIFF or JPEG files and must be at least 3 in.by 5 in. with a resolution of 300 dpi or greater. A captionshould be supplied for each graphic element.

� Use the units of measurement from the researchdescribed and provide conversions in parentheses, as appro-priate. The International System of Units (SI), the updatedversion of the metric system, is preferred. In the text, the SIunits should be followed, when appropriate, by the U.S.customary equivalent units in parentheses. In figures andtables, the base unit conversions should be provided in afootnote.

NOTE: Authors are responsible for the authenticity of theirarticles and for obtaining written permissions from pub -lishers or persons who own the copyright to any previouslypublished or copyrighted material used in the articles.

I N F O R M A T I O N F O R C O N T R I B U T O R S T O

TR NEWS

The Transportation Research Record: Journal of the Trans-portation Research Board (TRR) has long been recognizedas one of the leading sources for scholarly research andpractical papers on all aspects of transportation. Paperspublished in the TRR have undergone rigorous peerreview refereed by TRB technical committees.

TRR Online builds on the publication’s reputation forhigh-quality papers and extends the journal’s reach,increasing accessibility to a wealth of information. Theservice offers electronic access to the full text of morethan 9,600 peer-reviewed papers published in the TRRseries since 1996 and is updated as new papersbecome available.

The TRR Online service allows all visitors to locatepapers of interest and to review the abstracts. Accessto the full papers is available to TRR Online subscribersand to employees of TRB sponsors. Other users maypurchase complete individual papers.

To search abstracts, visit www.TRB. org/TRROnline. You’llalso find more information about the TRR Online service,subscriptions, and pricing. Or you can call the TRB Book-store at 202-334-3213; e-mail TRBSales@nas.edu.

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