IA VerkehrsberuhigungDesign for an AmericanRoadBY KOPL HALPERIN AND ROBERT HUSTON

The appearance of the ITE guidebookResidential Street Design and Traffic

Controll in 1989 should have signaledthe start of a new era for American citystreets. Experiments had begun in theNetherlands in the late 1960s to make amore forgiving roadway out of whatwas known to be the most dangeroustype of roads. The deadliest roads are“obsolete facilities where increasingtraffic speeds, volumes and vehicle per-formance have exceeded the originaldesign parameters. ”2 In the words ofanother author, these are “roads thatwere mostly built for horse traffic. It isnot surprising that an accident problemhas arisen.”3

By 1976 systematic attempts to applythe Dutch experience had begun inGermany.4 These were calledVerkehrsberuhigung, translated as“transportation calming. ” The firstguide in English to the use of thesetechniqties was Appleyard,5 followed bythe ITE guidebook and more recentlyby Civilised Streets.4 Civilised Streets not

only catalogs the techniques but chartstheir successes at reducing crash rates.

Now, after 15 years of European suc-cesses, Great Britain also has begun toapply Verkehrsberuhigung. It is inter-esting that the United States and

Conversion FactorsTo convert from ~ multi~lv by

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Canada have not. Perhaps this isbecause the authors of these guideshave used European models as illustra-tions. These European models appearforeign to American traffic plannersand drivers. Native North Americanroad elements that would achieve thesame goals have been overlooked.

A design is presented here that usesAmerican road elements forVerkehrsberuhigung. The primary aimis greater safety. It should also con-tribute to urban revitalization, as suchdesigns have done in Europe.b

Site Selection

A preliminary work for site selectionpreviously was published.’ Death rateson state traffic routes in Erie County,Pa., were found not to be a function oftraffic volume, which supports earlierpublished work reviewed by Hauer.8

The highest fatality rate route wasselected for redesign. It should bepointed out that any route can be madesafer; limited resources should be spenton those routes that pose the greatestrisk. The redesign shown is site specific,but similar use can be made of locallyfamiliar elements on any route needingredesign. The highest fatality rate routein Erie County is S.R. 4018 or Alternate5, a 9.6-mile collector or minor arterialentirely within the urban district. It car-ries up to 9,500 cars a day.9 This routehad 52 fatalities between 1961 and 1990.Figure 1 maps these fatalities. Thedeaths are distributed over the entirelength of the road; there are no black

spots. A black spot is a particular high-crash location, for example, a singleintersect ion.

Figure 1 also shows the remarkablenumber of schools along this route.Roads are a special hazard for 6- to 9-year-olds.9 Roughly 30 percent of child-hood pedestrian traffic casualties arechildren going to or from school. bBeginning in 1972, the Japanese govern-ment devoted considerable effort toimproving safety in school zones. Withinfive years they had reduced childhoodpedestrian casualties by half.l”

The portion chosen for the redesignis segments 120 through 140 of S.R.4018. It is a six-block (three-quartermile) stretch of what local residents callW. Sixth Street, from Cranberry toCherry streets. There are two elemen-tary schools located right along theroute in this one portion. In addition,children walk this route to four otherschools.

Six blocks to the south is 12th Street,S.R. 5, a six-lane principal arterial andmajor truck route. This six-lane routecarries 30,000 cars a day. Six blocks tothe North is “Oth” Street, the BayfrontHighway. The Bayfront Highway is athree-lane urban bypass, opened inOctober 1990. As Levinson states, theopening of urban bypasses often leads toexcess capacity on existing city streets.11This has certainly been the case in Erie.Figure 2 shows the capacity of Oth to12th streets along with the total averagedaily traffic. It can be seen that evenclosing a street would not affect thelevel of service on any parallel route.

28 ● ITEJOURNAL ● APRIL 1994

The design in this articles is not aimed atclosing the road, but merely at loweringthe crash rates by enforcing the speedlimit. But the American Association ofState Highway Transportation Officials’(AASHTO’S) Green Book12 states thata minor arterial “ideally does not pene-trate identifiable neighborhoods. ” Toavoid conflict, through traffic can berouted to two nonresidential routes, theBay front Highway and S.R. 5 (12thStreet).

S.R. 4018 is not used by emergencyvehicles (as confirmed by ambulance, fireand polic officials), and since the openingof the Bayfront Highway, S.R. 4018 is notused by truckers. Although 95 percent ofthe traffic is passenger car, it also is a busroute, because the design allows for thelarge turning radius of a bus.

The Design

A computer-aided design drawing ofthe basic design is shown in Figure 3.An artist’s rendering of the design isshown in Figure 4. For comparison, aphotograph of the existing route isshown in Figure 5. The existing route is36-feet (ft) wide. It consists of two cart-ways, two bikeways and a parking lane.All are retained.

The techniques of Verkehrsberuhi-gung chosen for implementation andthe elements of the design are givenbelow. All of these techniques anddesign elements must be unified intoone aesthetic whole.

Following are the elements exam-ined in detail.E Concrete pavers. Concrete pavers arethe only element of the design to besomewhat new to Erie drivers. Theirnearest use on a major street pavementproject is in downtown New Castle, 60miles to the south. Pavers are a provenpart of European successes in trafficsafety. 13 Flink states that Americam

like technological solutions to prob-lems.14 Working with a WesternPennsylvania paver manufacturing firmhelped get the right textures for thecartways, bikeways, parking and detailwork.■ Clay-shale brick crosswalks. Red con-crete pavers would work, but for aes-thetics and continuity with Americantradition, real red brick was chosen.The design combines the appeal of tra-dition and respect (brick) with theappeal of high technology (concrete

Figure 1. Erie, Penn., urbanized area showing S.R. 4018 traffic deaths.

pavers). Aesthetics are extremely vard style is quite familiar to local dri-important in gaining public acceptance. vers. In fact, the redesign intersects two■ Central boulevard. Again, an existing boulevards, at Cranberry StreetAmerican element is used. This boule- and at Liberty Street. In 30 years there

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Figure 2. Erie roadway capacity Bayfront to S.R. 5, east-west routes, Cranberry toCherry.

has never been a fatality on the boule-vard part of either Cranberry or Liberty.

Recent work by the FloridaDepartment of Transportation15 andthe Georgia Department ofTransportation lb has shown that amountable curb median can have anenormous positive influence on trafficsafety. In this design, a mountablemedian is used for those areas that can-not have a boulevard because of theturning radius of a bus. Neither mount-able curb nor boulevard would interferewith the turning radius of a car.Otherwise, a boulevard is preferable to

mountable curb, especially in a snow-belt region.

The boulevard provides refuge topedestrians and greater visibility. It sep-arates the traffic streams, and theboulevard lowers the lateral clearance,an essential component.17 Finally, theboulevard increases beauty and thusimproves the respect drivers will paythe district. Drivers will not be as likelyto speed through a neighborhood theyrespect.I 9-ft lanes. Both the AASHTO Green

Book12 and ITE’s Traffic EngineeringHandbook18 give 9-ft lanes as an

acceptable standard. 9-ft lanes are cer-tainly familiar to Erie drivers. There is asurprising lack of published research inNorth America on the effects of lanewidth on speed and safety on any roadsother than interstates.19 But in Europethis is not the case. Hass-Klau et al.4 areadamant that lane widths greater than 3meters (m) are detrimental to safety onolder urban roads. Our own measure-ments of snow patterns revealed 7-ft 6-inches (in.) to 8-ft 6 in. as the widthscreated by drivers exercising caution., Curb bulbs. Curb bulbs are an impor-tant part of Verkehrsberuhigung instal-lations. Residents in Erie are familiarwith Curb bulbs, especially along PerrySquare, a park that lies on S.R. 4018.The function of curb bulbs is to narrowthe apparent horizontal alinemental soas to induce the driver to choose lowerspeeds. Another function is to delineatethe cartway, so that the driver cannotencroach on the bikeway or parking.Currently, drivers along S.R. 4018 usethe parking lane as a second traffic lane,a dangerous practice, Curb bulbs wouldeliminate this. Finally, the curb bulb canbe planted with flowers, enhancingrespect for the district and thus lower-ing speeds.

There are three identical blocks inthe project, the three blocks of segment120. The number of midblock curb bulbsvaries from one block to the next, forresearch purposes. It is hoped that theoptimal spacing for desired speeds can

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30 ● ITEJOURNAL ● APRIL 1994

be determined. It is known what spacingis needed between vertical realignmentssuch as speed plateaus and pillows.4 Ifthe same effects can be achieved withhorizontal realignment, this would bemore familiar to American drivers andthus a better choice, but this wouldrequire further research.■ Reflecting bollards. Reflecting bol-lards need no introduction to Americantraffic planners. They help delineate theroadway under conditions of limitedvisibility.■ Stop signs. Stop signs are one of thefew proven methods to lower crashrates.20 This recently was confirmed byLaPlante and Kropidlowski.21According to LaPlante andKropidlowski, stop signs are ineffectualor even counterproductive on roadswith greater than 12,000 cars a day. Thepresent traffic volume in the re-designroute section is 6,000 cars a day; thenew bypass has removed 3,000 cars aday. The design volume is 2,000; it isexpected that through traffic will re-route to the Bayfront Highway bypass.

Rerouting does not necessarily occur

after a Verkehrsberuhigung installation;it depends on the availabity of alternateroutes.4 In a district with large numbersof faster parallel bypasses available andsevere overcapacity, rerouting willprobably occur. According toAppleyard, diverting traffic aloneincreases safetys; according to Hauer,slowering traffic volume does not neces-sarily increase safety. Safety of a routedoes not appear to depend on the trafficvolume. It should be pointed out thatboth the population and the traffic vol-ume in Erie County, Erie City and inthe immediate district have been declin-ing for many years.22

It is recommended that all intersec-tions within the redesign district be re-signed to multiway stops. Currently,three intersections have traffic lights; itis not known what happens when trafficlights are replaced by stop signs. It isbelieved that multiway stop signs are ofsuch known safety advantage that theyshould be specified whenever possiblein urban residential districts. This isespecially important in school zones.■ Lower posted speed. It is well known

that drivers do not drive the postedspeed.23 On the road in question, theposted speed is 25 miles per hour(mph), and the overall design is aimedat enforcing that speed limit. The cur-rent 85th percentile in the redesign arearanges from 34 mph to 38 mph depend-ing on the segment. In order to con-vince the driver that the optimum speedhas now changed, the design includeschanging the posted speed from 25 mphto 20 mph. The entire district is a schoolzone, and in conjunction with schoolzone signs, this new posted limit shouldnot meet with resistance and should aidthe other design elements in convincingdrivers to select speeds below 25 mph.Speed limits of 20 mph do not currentlyexist in Erie but are common inChicago neighborhoods.

From Smeed in 196023 to Evans in1991~4 the evidence shows that loweringspeed limits does lower the averagespeed of the road and does lower thecrash rates. The success of this projectdoes not depend, however, on the effectsof speed limits. The redesign insteaddepends on engineering techniques.

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■ Angle-in parking in some places. Itwas feared that the redesign wouldeliminate essential parking spaces. Aparking survey was done and found thatthe parking along the route was utilizedless than 10 percent at all times of theday and night. There were two excep-tions to this, one was in front ofEmerson-Gridley Elementary School insegment 131.

The other location in need of greaterparking is the strip of small shops at thecorner of Cascade Street in segment120. The redesign includes eight angle-in spaces, where currenlty there is con-crete pavement at sidewalk grade. Theshops will thus take on the aspect of asmall-town downtown. This shouldincrease trade, and shopkeepers areuniformly supportive of this project.

complicated. They involve comparingthe route to existing routes in the Erieurban district and comparing the extantdata to data predicted from Nilsson’sequations on crash rates and severityrates as a function of route speed.25

In Pennsylvania, a reportable crashis one in which either the vehicle wastowed or a person was treated forinjury, or both. The design should beable to reduce the number of reportablecrashes by 34 percent and the numberof injuries by 57 percent.

The fatality prediction is more strik-ing. Fatalities increase much morerapidly with increasing route speed thando overall crashes. The current expect-ed value is one fatality on this route sec-tion every 10 years. The redesign shouldreduce this to one every 70 years, andchildhood pedestrian fatalities should

from 14 a decade to between two andthree. That is, 11 or 12 deaths a decadethat currently occur could be prevented.

Prospects

The proposed design is, like anyroad design, site specific. Whether itgets built at the particular site is a politi-cal decision. Unfortunately, as Kraaystates, transportation safety has a lowpolitical priority.b

The basic elements of the analysisand of the design shown here can beadapted to any urban route. Identifyinga high death rate location on an oldhorse road probably means finding aplace needing redesign.

For more than 20 years, successfuloverseas experimentation with roadredesign has lowered crash rates. If

Expected Crash fall from one every 30 years to one Amer~an road design elements are

Reduction every 200 years. If the redesign were used, many American urban districtsapplied to the entire length of S.R.

The crash reduction calculations arecould rapidly duplicate these successes.

4018, the number of fatalities would fall This design, it is hoped, could be adapt-

Figure 4. Artist’s rendering of Verkehrsberuhigung design.

32 ● ITEJOURNAL ● APRIL 1994

ed elsewhere. Locally familiar elementsshould be used wherever possible. It is afertile area for further research, butmore importantly, lives can be saved.

Finally, Wilde states that the successof any transportation safety improve-ment depends on its being “psychologi-cally invisible. ”zc Evans arrives at thesame conclusion: “Safety may best beadvanced by drivers not having tochoose between driving habits morelikely to lead to crashes than those lesslikely to lead to crashes. ”24Verkehrsberuhigung, when properlydone with an eye for aesthetics andneighborhood improvement, leads to asafer transportation system without dri-vers feeling restrained.

Acknowledgements

This article benefitted from discus-sions with numerous people concernedwith the use of the road in variouscapacities. It would not have been pos-sible without the help of Bob Welling ofLampus Inc. of Springdale, Pa., and JimRedman of North American Woonerfof Los Alamos. N.M.

Figure 5. Intersection shown in Figure 4, present configuration.

References “Hazardous Road Locations: Identification

1. Homburger, W., E.A. Deakin, P.C.and Counter Measures.” OECD, Paris, 1976,

Bosselmann, D.T. Smith Jr. and B. Beukers. ~,p. 28,

Residential Street Design and Traffic Crmtrol.Norman, L.C. “Road Traffic Accidents:

Englewood Cliffs, NJ: Prentice Hall, 1989.Epidemiology, Control and Prevention. ”

2. Organization for Economic Cooperation andPublic Health Paper No, /2. World Health

Development Road Research Group.Organization, Geneva, 1962. Cited inLeeming, J, J,, Road Accidents, Cassell,

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4.

5.

6.

7.

8.

9,

10

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London, 1969, p. 34.Hass-Klau, C., 1, NoId, G. Becker and G.Crampton, Civilised .SIr-eet.s: A Guide [oTraffic Calming, Environmental andTransporfPlanning. Brighton, England: 1992.

Appleyard, Donald. Livabk .SIreem. Berkeley,CA: University of California Press, 1981.Kraay, Joop H.,Saf_e(yin Residen[ia/Areas;The European Viewpoint. Report R-87-20.Liedschendam, The Netherlands: Institutefor Road Safety Research SWOV, 1987.Halperin, K. and J. Redman, “Route fatalityrisk as a measure of travel fatality risk. ”RISK—Issuesin [{ealth and Safety, Vol. 4,No. 1 (1993): 1-15.Hauer, Ezra. The JOr@-reeringr)fSafetyandthe Safety of Engineering, irr .1. Peter Rothe,cd., Challenging the Old Order: Towards NewDirections in Traffic Safety Theory. NewBrunswick, NJ: Transaction Publishers, 1990,pp. 39-71.European Conference of Ministers ofTransport. Principal Action.r of the ECMTinthe Field of Road Safely, ed. 1986. Paris,France: ECMT, 1986, p. 73.Japanese Government. White Paper onTransportationSufety, 1977editiorr.Tokyo,Japan: International Association of Trafficand Safety Sciences, 1977, p. 26.Levinson, Herbert S. “Streets for People andTransit. ” Transportation Quarterly, Vol. 40,No. 4 (October1986): 503-S20,American Association of State Highway andTransportation Of ficials(AASHTO). .4Policy on Geometric Design of Highways andStreets. Washington, DC AASHTO, 1990.Lilley, Alan A.A Handbook of.$egmentalPavirrg. London, England E & FN Spon, 1991.

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Flink, James J. The Car Culture. Cambridge,MA: The MIT Press, 1975.Wallwork, Michael J. and Theodore A.Petritsch. An Analysis of Pedestrian/VehicleCrashes in Two Way Left Turn Lanes.Jacksonville, FL: Florida Department ofTransportation, 1992.

Georgia Department of Transportation Officeof Traffic and Safety. Before/A fter Evaluationfor New Media Construction—MemorialDrive (S. R. 10), DeKalb County. Atlanta,GA: GaDOT, 1992.Warren, Davey L. “Speed Zoning andControl. ” Synthesis of Safety ResearchRelated to Traffic Control and RoadwayElements, Vol. 2, FHWA-TS-82-Z33.Washington, DC FHWA, p. 17-6.Robinson, Carlton C. “Highway Capacity.”Transportation and Traffic EngineeringHandbook. Englewood Cliffs, NJ: Prentice-Hall, 1976,pp. 309-376.Van Wenld, Stephen N. “GeometricDesignand Traffic Control Devices:Can I ProvokeYou?” lTEJournal, Vol. 62, No.4 (April1992):41-43.Hauer, Ezra. Review of Published Evidenceon the Safety Effect of Conversion from Two-Way to Four-Way Stop Sign Control. Toronto,Canadal: University of Toronto Departmentof Civil Engineering, 1985 (citedin Evans, L.,Trrrfflc Safety and the Driver, Van NostrandReinhold,NewYork, 1991, p. 85).LaPlante, John N, and Chester R.Kropidlowski. “StopSign Warrants: Time forChange. ” ITE Journal, Vol. 62, No. 10(October 1992): 25-29.U.S. Department of Commerce Bureau of theCensus. 1980 Census of Population and

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24.

25.

26,

Housing, Census Tracts, Erie, PA StandardMetropolitan Statistical Area, 1983, and 1990Census of Population and Housing, SummarySocial, Economic & Housing CharacteristicsPennsylvania, 1992.Smeed, R.J. “The Influence of Speed andSpeed Regulations on Traffic Flow andAccidents. ” Roads and Road Construction,Vol. 38 (December 1960): 393-397,Evans, Leonard. Traffic Safety and the Driver,New York, NY: Van Nostrand Reinhold,1991, p. 156,Nilsson, G. Effects of Speed Limits on TrafficAccidents in Sweden. Linkoping, Sweden:National Raod and Traffic ResearchInstitute, 1990 (reviewed in Leonard Evans,Traffic Safety and the Driver, Van NostrandReinhold, New York, 1991, pp. 153-5; andNilsson, G, “International Symposium on theEffects of Speed L]mits on Traffic Accidentsand Transport Energy Use: The Effects ofSpeed Limits on Traffic Accidents inSwede n,” Organization for EconomicCooperation and Development, Paris,October, 1981 .).Wilde, Gerald J. S., “Beyond the Concept ofRisk Homeostasis: Suggestions for Researchand Application towards the Prevention ofAccidents and Lifestyle-Related Disease”,Accident Analysis and Prevention, v. 18, n. 5,1986, pp. 377-401. I

Kopl Halperin,Ph. D., is assistantprofessor of mech-anical engineering atPenn State at Erie—The Behrend Col-lege. He is the

author of numerous articles on the use ofinnovative materials to solve humanhealth risk problems; this research hastaken him into the area of transportationrisk. He is a member of the AmericanSociety for Engineering Education; thenational and Pittsburgh chapters of theAmerican Institute of Mining,Metallurgical and Petroleum Engineers;and the national and Cleveland chaptersof the Transporta-tion Research Forum.

Robert Hustonwas a senior inmechanical engi-neering at PennState—The BehrendCollege when thiswork was per-

formed. He is a Virginia State Cer~ifiedHighways Inspector. He had been withJ. W. Lassiter Concrete Inc. from 1983 to1989 and the Virginia Department ofTransportation from 1989 to 1990. Hecurrently is an air pollution control engi-neer for the Pennsylvania Department ofEnvironmental Resources—NorthwestRegion.

34 ● ITEJOURNAL ● APRIL 1994