Crash Reduction Factors for Rear End Collision Strategies ... · Crash Base Rates for Freeways/Reduction Strategies for Rear End ... GA 30356 13. Type of Report and Period Covered

1. Report No. FHWA/OH-2008/14

2. Government Accession No. 3. Recipient's Catalog No.

5. Report Date January 2009

4. Title and subtitle Crash Base Rates for Freeways/Reduction Strategies for Rear End Crashes - Volume 2: Reduction Strategies for Rear End Crashes in Ohio 6. Performing Organization Code

8. Performing Organization Report No. 7. Author(s) Prahlad D. Pant, Ph.D. Subarna Panta

10. Work Unit No. (TRAIS)

11. Contract or Grant No. 134230

9. Performing Organization Name and Address PDP Associates Inc. P.O. Box 888264 Atlanta, GA 30356

13. Type of Report and Period Covered 12. Sponsoring Agency Name and Address Ohio Department of Transportation 1980 West Broad Street Columbus, Ohio 43223

14. Sponsoring Agency Code

15. Supplementary Notes

16. Abstract The primary objective of this research was to systematically review past studies on rear end crashes, examine strategies for reducing rear end crashes on both freeway and non freeway facilities, and develop a set of rear end crash reduction strategies for use in Ohio, which will be appropriate for various traffic engineering solutions, operations and ITS improvements. Accordingly, this study conducted an extensive review of past literature related to rear end crashes and strategies to reduce them. A determination of specific strategies for a road safety improvement program requires an understanding of probable crash reduction capabilities for various geometric, operational and environmental factors on the roadways. Studies of crash reduction strategies have usually focused on before-and-after comparisons of specific locations or conditions. Based on the data provided by the Ohio Department of Transportation, this study attempted to examine the crash reduction capabilities for signalized intersections, unsignalized intersections, freeways and non-freeways where countermeasures were implemented. An attempt was made to compute crash reduction factors for rear end collisions for these roadway facilities. However, this task could not be performed because of the severe limitations in the ODOT countermeasure and roadway site data. In response to the researchers’ request for additional data, ODOT decided not to proceed ahead with this research as it required the dedication of district resources that were not currently available. It was believed that breaking the project into smaller, more manageable pieces, would not yield results that would be statistically significant. There were also several national projects underway which would limit this project’s benefits. In view of these circumstances, ODOT decided to terminate the contract for this project and all work stopped. 17. Key Words Rear End Crashes, Rear End Accidents, Crash Base Rate, Accident Base Rate, Freeways, Crash Density, Crash Rate, Accident Density, Accident Rate.

18. Distribution Statement No restrictions. This document is available to the public through the National Technical Information Service, Springfield, Virginia 22161

19. Security Classif. (of this report) Unclassified

20. Security Classif. (of this page) Unclassified

21. No. of Pages 22. Price

Form DOT F 1700.7 (8-72) Reproduction of completed pages authorized

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Crash Base Rates for Freeways/Reduction Strategies for Rear End Crashes Volume 2: Reduction Strategies for Rear End Crashes in Ohio

Prepared by Prahlad D. Pant, Ph.D. Principal Investigator

and Subarna Panta

Systems Analyst

Research Performed By PDP Associates Inc.

P.O.Box 888264 Atlanta, GA 30356

Research Performed Under State Job No.: 134230 Agreement No.: 20819

Prepared in cooperation with Ohio Department of Transportation

and U.S. Department of Transportation, Federal Highway Administration.

January 2009

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Disclaimer Statement

The contents of this report reflect the views of the authors who are responsible for the facts and accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the Ohio Department of Transportation or the Federal Highway Administration. This report does not constitute a standard, specification, or regulation.

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ACKNOWLEDGEMENT The researchers thank the following officials of the Ohio Department of Transportation for their assistance in the conduct of this research study.

• Ms. Monique Evans P.E., Administrator, Office of Research & Development; • Ms. Jennifer Townley P.E., Administrator, Office of Systems Planning and Program

Management; • Mr. Don P. Fisher P.E., Manager, Office of Systems Planning and Program

Management; • Mr. Jonathan Hughes P.E., Manager, Office of Systems Planning and Program

Management; • Mr. Tom Ramsay, Office of Systems Planning and Program Management

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TABLE OF CONTENTS

1.0 Statement of the problem - - - - 15 2.0 Objectives - - - - 19 3.0 Background and Significance of work - - - - 21 4.0 Further Review of Crash Reduction Factors with Medium to High Level of Predictive Certainty for Rear End Collision Reduction Strategies - - - - 35 5.0 Possible Causes of Rear End Crashes and their Reduction Strategies - - - - 37

5.1 Possible Causes of Rear-End Crashes - - - - 37 5.2 Reduction Strategies for Rear-End Crashes - - - - 38

6.0 Data Collection and Analysis - - - - 49 6.1 Data Collection - - - - 49 6.2 Data Compilation - - - - 49 6.3 Request for Data - - - - 53

7.0 Conclusions - - - - 57

Reference - - - - 59 Appendix I Simple Before and After Comparison - - - - 63 Appendix II AID Tree Diagram for Rear End Crashes - - - - 85

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LIST OF TABLES

Table 1. Rear End Crashes in Ohio from 1998 – 2007

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Table 2. Rear End Crash reduction Factors – Ohio 1997

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Table 3. Reduction Strategies for Rear End Crashes at Signalized Intersections

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39

Table 4. Reduction Strategies for Rear End Crashes at Unsignalized Intersections

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42

Table 5. Reduction Strategies for Rear End Crashes at Non-Freeways

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44

Table 6. Reduction Strategies for Rear End Crashes at Freeways

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Table 7. Simple Before Study for Countermeasures employed on intersections in year 2004

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50

Table 8. Countermeasures Listed in ODOT Data

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Table 1.1: Simple Before and After Comparison for Countermeasures employed in Intersections from year 2001 – 2004

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65

Table 1.2: Simple Before and After Comparison for Countermeasures employed in Interstate from year 2001 – 2004

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Table 1.3: Simple Before and After Comparison for Countermeasures employed in Non-Interstate from year 2001 – 2004.

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LIST OF FIGURES

Figure 1. AID Tree diagram for rear end accident density for all 12 districts of rural highways without intersection.

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89

Figure 2. AID Tree diagram for intersections With One Way Stop Sign - No Control Legs - Rear end Crashes

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90

Figure 3. AID Tree diagram for T Intersections with One Way Stop Sign - Stop Control Legs - Rear end Crashes

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91

Figure 4. AID Tree diagram for Two Way Stop Control Intersections- No Control Legs - Rear end Crashes

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Figure 5. AID Tree diagram for Two Way Stop Control Intersections- Stop Control Legs - Rear end Crashes

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Figure 6. AID Tree diagram for Flashing Beacon Control Intersections- No Control Legs - Rear end Crashes

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Figure 7. is for AID Tree diagram For Flashing Beacon Control Intersections- Stop Control Legs - Rear end Crashes

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Figure 8. AID Tree diagram for Signalized Intersection Legs - Rear end Crashes

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Figure 9.AID Tree diagram for rear end accident density for statewide freeways.

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Figure 10. AID Tree diagram for rear end accident rate for statewide freeways.

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VOLUME 2. REDUCTION STRATEGIES FOR REAR END CRASHES

1.0 Statement of the Problem

The US Department of Transportation reports that 5.97 million crashes occurred in the United States in 2006 (1). The damages and injuries from these crashes cost the United States billions of dollars each year. A Federal Highway Administration (FHWA) publication indicates the cost of crashes at 230 billion dollars each year (2). The National Highway Traffic Safety Administration (NHTSA) 2003 General Estimates System data suggests rear end crashes at 28 percent of the total crashes (3). The Ohio Department of Public Safety has reported that a total of 328,742 traffic accidents occurred in 2007. Of these, 87,976 or 26.76 percent of the total accidents were rear end collisions. Statistics show that the proportion of the rear end collision to the total traffic accident has remained almost constant over the last ten years. The data for rear end crashes over the last decade is given below (4).

Table 1: Rear End Crashes in Ohio from 1998 - 2007

Year Total Crashes

Rear End Collision

Percentage of Rear End Collision

2007 328,742 87,976 26.76 2006 334,206 90,933 27.21 2005 358,127 94,077 26.27 2004 381,639 101,682 26.64 2003 392,683 102,199 26.03 2002 386,076 101,619 26.32 2001 387,075 102,714 26.54 2000 386,122 100,410 26.00 1999 385,704 103,445 26.82 1998 377,920 102,871 27.22 (Source- Traffic Crash Facts, Ohio Department of Public Safety,

http://www.publicsafety.ohio.gov/crashes/crash_facts.asp)

A conference presentation titled “Strategies for Improving Safety and Mobility on Ohio Roads” points out that 43 percent of all freeway crashes occur on 12.5 percent of the freeway system and 19.4 percent of all non-freeway crashes occur on 1.9 percent of the non- freeway system. It also indicates that 31.3 percent of freeway rear end crashes occur on 4.3 percent of the freeway system (5). Ohio DOT aims to reduce the total number of crashes 10 percent by 2010 and reduce rear end collision 25 percent by the year 2010 (6 ).

http://www.publicsafety.ohio.gov/crashes/crash_facts.asp

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The Safety Core Business Unit of the Federal Highway Administration conducted a program review of the Highway Safety Improvement Program in six states (Delaware, Oregon, Connecticut, Florida, Ohio and Iowa) during 2001.The findings related to crash reduction factors are as follows:

• Oregon extensively used customized crash reduction factors. • Connecticut used both cost/benefit analysis and crash reduction factors in selecting

projects for implementation. • Two districts of Florida DOT that were visited, used statewide crash reduction factors

to perform benefit/cost analysis (7). • Ohio ranks second to California in terms of safety funding (6, 7).

In 1997, ODOT identified 12 crash reduction factors related to rear end crashes which are shown in the table below (8).

Table 2: Rear End Crash reduction Factors – Ohio 1997

No. Description CRF 1 Lane use signs – overhead 0.1 2 Install PTSWF sign/flasher[for approach speeds > 45 mph] 0.6 3 Widen pavement to provide 2WLTL 0.2 4 Install left turn bay & extra pavement without signal 0.2 5 Install left turn bay & extra pavement with signal 0.2 6 Widen for left turn lane, including resurfacing 0.2 7 Widen for right turn lane, including resurfacing 0.2 8 Install traffic signal - all types -0.1 9 Add left turn phase with new left turn lane 0.2 10 Add left turn phase with existing left turn lane 0.1 11 Install optically programmed heads 0.1 12 Relocate driveway entrance 0.2

A safety study generally focuses on “analysis of roadway and traffic related data to determine the possible cause of identified crash pattern and provide alternative countermeasures to mitigate the crash patterns” (10). For safety studies, ODOT uses crash data for a minimum of three years. The crash data is reviewed for the following crash characteristics of a site and a detailed analysis is done to identify the problems and their possible causes.

1. Crash Type - Angle, Backing, Fixed Object, Sideswipe, Head-On, Rear End 2. Time of Day – Day, Night 3. Pavement Condition –Wet, Dry 4. Severity – PDO, Injury/Fatalities

After possible causes are identified, every alternative measure of improvement including “do nothing” is analyzed. The rate of return is calculated, which “determines the benefit expected

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to be obtained by the improvements (10).” Crash reduction factors are used in computing the rate of return for both PDO and Injury/Fatalities crashes. A user friendly Excel worksheet is developed for this purpose (11). However, currently ODOT does not have a uniform and complete set of statewide strategies for reducing rear end crashes.

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2.0 Objectives: The primary objective of this research study is to systematically review past studies on rear end crashes, examine strategies for reducing rear end crashes on both freeway and non freeway facilities, and develop a set of rear end crash reduction strategies for use in Ohio, which will be appropriate for various traffic engineering solutions, operations and ITS improvements. The study was designed to perform the following tasks to fulfill the objectives.

1. Conduct a thorough review of literature. 2. Obtain crash, traffic and roadway inventory data from ODOT, and prepare a master

database for use in this study. 3. Analyze the above mentioned ODOT data and determine crash reduction factors for

rear end collision reduction strategies. 4. Prepare a set of strategies for reducing rear end collisions and provide appropriate

recommendations.

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3.0 Background and Significance of Work Different strategies could be adopted for cost effective safety improvements in all types of roadways. Determination of specific countermeasures for the road safety improvement program requires an understanding of probable crash reduction capabilities for various geometric, operational and environmental factors on all types of roadways. Crash Reduction Factors (CRFs) are such tools that many agencies use to estimate cost effective countermeasures for safety improvement programs. Crash reduction factors (CRFs) are used to determine probable crash reduction capabilities for various geometric, operational and environmental factors associated with specific improvements on different types of roadways including freeways, non-freeways and signalized and unsignalized intersections. Studies of crash reduction factors have usually focused on before-and-after comparisons of specific locations or conditions. This research effort has conducted an extensive review of past literature related to rear end crashes. The review of past literature includes countermeasures for the reduction of rear end collisions, causes of rear end crashes and crash reduction factors related to rear end crashes. One such research paper titled “Attention Based Model of Driver Performance in Rear End Collisions” published in 2000 in the Transportation Research Record focuses on the attention based model of driver performance in rear end collisions (12). This paper attempted to introduce an attention based rear end collision avoidance model “that describes the driver’s attention distribution, information extraction and judgment process”. The paper indicated that the model components “provide a structure for interpreting conflicting reaction-time data and also provide several important recommendations for the design of warning algorithms and displays.” Another research paper titled “Analysis of Design Attributes and Crashes on the Oregon Highway System”, and published in August 2001, explores the relationship between crash occurrence and roadway design characteristics (13). Studies were performed on both freeway and non freeway roadway facilities that were located on both urban and rural areas. The study findings indicated that numerous design characteristics and crash occurrence were statistically related. Another research paper titled, “Taking Tire Slip Ratio into Account and Estimating Friction Coefficients in Rear-End Collisions on Winter Roads” was published in the Transportation Research Record in 2001 (14). The primary focus of the study was to estimate the road surface friction coefficient in rear end collisions on winter road conditions in Japan. The study indicated that the friction ratio is dependent on tire slip ratio, particularly of a specific type of tire and also attempted to evaluate the relationship between improvement in traffic safety and increment in friction coefficient. The findings of the study suggested that accidents could be reduced by improving winter road conditions and increasing the friction coefficient. The study indicated that the rate of accidents in icy road conditions decreased by

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50 percent if the friction coefficient increased by 0.1. The study, however, concluded that more research is required to obtain most favorable friction coefficient threshold. Another research paper titled “Rear-End Collision–Warning System Design and Evaluation via Simulation” focuses on a rear end collision warning system that is built in a vehicle (15). A rear end collision warning system was designed and evaluated. In this system, a lead vehicle is able to warn the following vehicle if the later is coming close too rapidly. A warning algorithm was developed based on an appropriate warning distance. The factors considered, while designing the algorithm were minimizing the occurrence and severity of crashes and reducing the frequency of nuisance alarms. The findings showed that it was possible to design an effective rear end collision system which could minimize the occurrence and severity of crashes. The study recommended field studies to derive optimum values for design parameters. The Crash Reduction Information approved by the North Carolina DOT in 2002 (16) shows the following countermeasures listed for rear end crashes:

New traffic signal Closed loop signal system Left turn lane at intersection Right turn lane at intersection Increase turn lane length Continuous left turn lane Widening for additional lane Vertical realignment Improve skew angle Skid treatment Remove traffic signal Dynamic message sign

A research paper related to crash reduction factors, titled “Development of Crash Reduction Factors: Methods, Problems, and Research Needs” was presented at the 82nd annual meeting of the Transportation Research Board in 2003 (17). This paper examined the method, problems and research needs for the development of crash reduction factors. The emphasis was placed on the before-and-after study method as it is the predominant method of choice for development of crash reduction factors. The paper introduced and reviewed three different before-and-after methods:

The simple before-and-after method, The before-and-after study with comparison group method, and The before-and-after study with the empirical Bayes method.

A paper titled “Configuration Analysis of Two-Vehicle Rear-End Crashes” was presented at the 82nd annual meeting of the Transportation Research Board in Washington D.C on Jan 12-16, 2003 (18). This paper examined the role of light trucks in rear-end accidents. Light trucks are vehicles bigger and heavier than passenger cars and are more likely to affect the visibility of the passenger car driver. The study indicated that due to distraction and limited

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visibility there is a higher chance of rear end crashes when a regular passenger car follows a light truck vehicle. A paper titled “Driver Attributes and Rear-End Crash Involvement Propensity” was published by the National Highway Traffic Safety Administration (NHTSA) in March 2003 (19). This study explores statistical relationship between the crashes and the drivers who are involved in crashes. The primary sources of information for this study were General Estimates Systems (GES) and the Fatality Analysis Reporting System (FARS), both compiled by the National Highway Traffic Safety Administration (NHTSA). The findings of this study suggested a strong statistical relationship between the sex of the driver and the type of rear end crash and also between the age of the driver and the type of rear end crash. Some of the inferences made by the studies are:

Drivers under 18 have highest rate of rear end striking crashes. Probability of striking rear end crashes decreases with age. Young male drivers are more likely to be involved in rear end crashes than young

female drivers.

Another research paper titled “Examination of Crash Contributing Factors Using National Crash Databases” was published in October 2003 (20). This study was prepared by the National Highway Traffic Safety Administration (NHTSA) to examine the factors that contribute to some specific types of vehicle crashes. The research was based on crash data obtained from various sources. The research was divided into three phases. a) Phase one - comparison of the contributing factor distributions from different data sources in order to assess which database contains more information about the selected factors. b) Phase two – investigation of the issues of crash severity to see if the contributing factors varied depending on the severity of the crash. c) Phase three - determination of the contributing factors based on the pre-crash scenarios for each crash type. The findings included analysis of three different scenarios – single vehicle off road, lane change and rear end crashes. Inattention, alcohol/drugs, and speeding were found to be the major factors for all types of crashes. In the rear end crash analysis, three different scenarios were selected – lead vehicle decelerating, lead vehicle moving and lead vehicle stopping. The crash contributing factors for the later two scenarios were similar to all types of crashes. Inattention and speeding were the top two primary contributing factors for both scenarios. Findings from the rear end crash scenario analysis suggested that alcohol and drugs were higher contributing factors for the lead vehicle moving than the lead vehicle decelerating and lead vehicle stopping scenarios. Rear end collisions were found to be more likely to occur in situations involving the lead vehicle moving when the driver of the striking vehicle was under the influence of alcohol/drugs rather than if the striking vehicle was speeding. Intersections A project on development of crash reduction factors was done by Kentucky Transportation Institute in 1996 (21). This study was primarily based on surveys of other states that were using some form of crash reduction factors. This study extensively used data provided by 37 states. It indicated that 19 states had developed their own accident reduction factors and that

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18 states used reduction factors developed by other states. Based on the survey and review of past literature, this study recommended nine groups of accident reduction factors. The study also listed percent reduction of accidents for certain types of improvements. The reported improvement category for intersection that are related to rear end crashes are:

Channelization of left –turn lanes at no-signal intersection Additional left turn at signalized intersection Additional left –turn lanes at no-signal intersection

A report titled “Strategic Highway Safety Plan for Vermont” published in December 2001 (22) states its goal to minimize the occurrence and severity of crashes by identifying and implementing achievable and effective education, enforcement, engineering and emergency response initiatives. The report focuses on seven critical emphasis areas and has identified specific crash reduction strategies for each of them. The critical emphasis areas are as follows:

Keeping vehicles on the roadway and minimizing the consequences of leaving the road

Young drivers Improving the design and operation of highway interactions Increasing seat belt use and improving airbag effectiveness Reduced impaired driving Curbing speeding and aggressive driving Keeping drivers alert

The crash reduction strategies listed in the fourth critical emphasis area also targets the rear end crashes which occur in the intersections. The following strategies are listed in this area:

Improve visibility by providing enhanced signing and delineations Improve maintenance and visibility of signs and markings Improve geometry at intersections Implement physical changes on the approaches to and at intersections Improve driver compliance with traffic control devices and traffic laws at

intersections through increased enforcement Reduce speed at intersections Increase public awareness at High Crash Locations Implement a local program for identifying and prioritizing High Crash Locations

NCHRP Synthesis 310, Impact of Red Light Camera Enforcement on Crash Experience A Synthesis of Highway Practice was published in 2003 (23). The primary objective of this synthesis was to determine the impact of red light camera on crashes and their severity. The findings of the research suggest that the red light cameras could bring about slight increase in the rear end crashes and decrease in angle crashes. The synthesis however, cautions that more research is needed to reach a conclusive finding. NCHRP Report 500, Guidance for Implementation of the AASTHO Strategic Highway Safety Plan was published in 2003 (24). Volume 5 of this report outlines guidelines for addressing unsignalized intersection collisions and Volume 12 deals with the signalized intersection collisions. Intersections represent only a small part of the overall roadway system but intersection related crashes account for more than 50 of all crashes in urban areas

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and 20 percent in the rural areas. Rear end crashes constitute 6 percent of the crashes at signalized intersection and 1 percent at unsignalized intersection. Most of the objectives of this guidance relate to the physical improvement of signalized and unsignalized intersections. Though the strategies relate to all type of crashes many strategies are appropriate for rear end crashes. The guidance “provides a classification of strategies according to the expected time frame and relative cost.” The guidance also provides description of strategies and classifies the strategies into three types – proven, tried and experimental. Many of the strategies relate to rear end crashes. A research study titled “An Evaluation of Red Light Camera (Photo-Red) Enforcement Programs in Virginia: A Report in Response to a Request by Virginia’s Secretary of Transportation” and published in 2005 (25) focused on seven Virginia red light camera programs. The researchers claim that there was a ‘definite’ increase in rear end crashes after red light cameras were installed. The study also confirms that there was an increase in total injury after the camera was installed. A focus group study titled “Driver Attitudes and Behaviors at Intersections and Potential Effectiveness of Engineering Countermeasures” was published in 2005 (26). This research effort focused on identifying driver attitudes and behaviors with respect to four different intersection scenarios including rear end crashes. The engineering countermeasures discussed are intersection rumble strip and improved skid resistance or a combination of both. The report “Update of Florida Crash Reduction Factors and Countermeasures to Improve the Development of District Safety improvement Projects” was published in April, 2005 (27). The main objective of this study was to update the Florida DOT’s CRFs “and to develop a computer system to systematically maintain safety improvement projects implemented by its districts to facilitate regular CRF updates” The study also conducted survey of state DOTs. The improvement programs for rear end crashes being utilized by various DOTs include

Channelization intersection Painted Lane Protected lane with curb or raised bars Install two-way left-turn lane in median Channelize two-lane to three lane Channelize four lane to five lane Add left and right turning lanes with signal Provide right-turn lane Add left turn lane with physical separation Add left turn lane with painted separation Add turning lanes Add double left turn lanes Add T-intersection turn and bypass lane Detached left-turn lane Increase turning radii Improve sight distance Change all way stop sign from two-way stop sign Install lane use sign

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Remove unwarranted signal Install flashing beacon

Though most DOTs have used simple before-and-after and cross sectional methods for developing CRFs, this research study used Empirical Bayes method to overcome a statistical vulnerability. Crash reduction Analysis System Hub(CRASH), a web-based application system was developed as a part of this research effort to allow recording and maintaining projects, updating CRFs based on the latest available improvement project and crash data and applying CRFs in the benefit-cost analyses of specific projects. A research results digest 299 titled “Crash Reduction Factors for Traffic Engineering and Intelligent Transportation System (ITS) Improvements: State of Knowledge Report” was published in November 2005 by NCHRP (28). This digest provides an overview of the current status of the crash reduction factors for a variety of treatments and provides an outline of the “best available” crash reduction factors. This digest uses AMF (Accident Modification Factors) as the standard terminology as a means of being uniform with other continuing researches being done by NCHRP. AMFs or CMFs (Crash Modification Factors) are expressed as (1 – CRF). A CRF of 10% would be equal to 0.90 AMF. “CRFs are the quantitative results from research studies, indicating the percentage reduction in crashes that can be expected after implementing a treatment or program. AMF are derived from crash reduction factors and are used in predictive technologies to estimate the reduction of crashes that can be expected for a specific treatment or installation.” The report emphasizes the importance of AMFs in the decision making process of the states and addresses the “ impediments that prevent more extensive use of AMFs” which affects the quality of the factors which is being used by many states. The issues addressed in the report are:

Origins/Transferability of AMFs Methodological issues Variability Crash Migration and spillover issue Lack of information in effectiveness Combinations of treatments Publication/Citation issues

This digest lists 100 specific treatments which include both traditional and ITS countermeasures. Out of these 100 treatments 20 were found to be credible with high to medium level of predictive certainty. This digest gives a summary of the research study from which the AMF was developed. The crash reduction strategies that were included in the summaries of the research studies that developed AMFs for intersections and which are related to the rear end crashes are follows:

Install roundabout Add exclusive left-turn lane Add exclusive right-turn lane Install a traffic signal Remove a traffic signal Modify signal change interval

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Convert to all-way stop control Install red light camera

The final report of this project will include a comprehensive summary of the best AMFs that are available at that time. A research study titled “Update and Enhancement of ODOT's Crash Reduction Factors” was published in June 2006 (29). The main objective of this study was to update the list of crash reduction factors for Oregon Department of Transportation. ODOT has been using the current list of countermeasures since early 1990’s. The study lists the three distinct types of countermeasures and their crash reduction factors:

1. which are backed by robust research 2. with limited research and 3. discussion only (no research)

The countermeasures include design improvements, Operations/ITS and markings and signs. The listed countermeasures for intersection that are backed by robust research and that relate to rear end crashes are:

Add left-turn-bay, signalized intersection Add left-turn-bay, unsignalized intersection Add right-turn lane on major road, signalized intersection Add right-turn lane on major road, unsignalized intersection Add two way left turn lane Install automated enforcement of red light violations Lengthen the yellow change interval to ITE guidelines Remove traffic signal from one way street

The countermeasures include design improvements, Operations/ITS and markings and signs. The listed countermeasures for intersection with limited research and that relate to rear end crashes are:

Convert 4-lane into 3-lane Improve intersection sight distance/clear sight triangles Provide illumination for intersection

The Illinois Department of Transportation has published a Highway Safety Improvement Program under Illinois Comprehensive Highway Safety Plan. The program includes Guidelines to Counter Measure Effectiveness & Crash Reduction Factor effective November 2006 (30). The countermeasures and CRFs that concern intersection rear end crashes are

Channelization Lane Addition Left turn Lane, Right Turn Lane Bidirectional Install roundabout, Overhead sign tuss, Advance warning signs, Signal modernization, Advance warning with flasher, Add traffic actuation, Curb Parking removal.

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Freeways A project on development of crash reduction factors was done by Kentucky Transportation Institute in 1996 (21). This study was primarily based on surveys of other states that were using some form of crash reduction factors. This study extensively used data provided by 37 states. It indicated that 19 states had developed their own accident reduction factors and that 18 states used reduction factors developed by other states. Based on the survey and review of past literature, this study recommended nine groups of accident reduction factors. The study also listed percent reduction of accidents for certain types of improvements. The improvement category related to for all types of crashes in the freeway are:

Construct interchange Modify Entrance/Exit Ramp Frontage Road Glare Screen for night accidents

The countermeasures include design improvements, Operations/ITS and markings and signs. The listed countermeasures for freeway with limited research and that relate to rear end crashes are:

Provide illumination on highway sections Install ramp metering Provide illumination for freeway

A research study titled “Advance Warning of Stopped Traffic on Freeways: Current Practices and Field Studies of Queue Propagation Speeds” was published by the Texas Transportation Institute in June 2003 (31). This study focused on the following three major causes of slow/stopped traffic conditions:

Congestion related to recurrent traffic conditions Congestion related to work zones Congestion related to incidents

The following significant findings related to rear ends collision are summarized in the report. Most frequent type of collision in the United States especially at work zones is rear-

end collisions Rear-end crashes on freeways are caused by normal speed traffic encountering

slow/stopped traffic on main lanes or ramps The following significant findings related to driver behavior approaching slow/stopped traffic are summarized in the report

Hard braking maneuvers between 1 and 16 per 1000 approaching vehicles observed at two work zone sites.

5% of vehicles rapidly approached end of queue despite advance warning The study summarizes several studies that claims to have estimated the benefits of advance warning of slow/stopped traffic on freeways

0.5 seconds of an additional warning time of slow/stopped vehicle could reduce rear end collisions by 60 % and an extra second of warning time could reduce rear end collisions by as much as 90%.

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Queue warning systems in Netherlands, Germany and England were found to significantly lower the rate of rear end collisions on freeways

A report titled “Advance Warning of Stopped Traffic on Freeways: Field Studies of Congestion Warning Signs” was published by the Texas Transportation Institute On March 2005 (32). This research study addresses a major safety concern leading to rear end collisions on freeways, which is traffic flowing at normal speed encountering unexpected slow or stopped traffic. The main objective of this study in the first phase was to conduct a literature review to determine current practices for advance warning for stopped traffic and in the second phase was to test two advance warning techniques using static warning signs on the Dallas area freeway. The research study identified the following four basic problem areas where advance warning of slow of stopped traffic are recommended.

Sight distance constraints Recurrent congestion Construction/maintenance zones Incidents

The research study observes that no standard for advance warning exists and further studies are needed to address other areas including, desirable messages for various conditions and assessment of the prevalence of rear-end crashes where congestion and horizontal or vertical alignment visibility constraints exist. The Research Results Digest 299 titled “Crash Reduction Factors for Traffic Engineering and Intelligent Transportation System (ITS) Improvements: State of Knowledge Report” published in November 2005 by NCHRP (28) and discussed earlier under the section of Intersection lists two countermeasures exclusively for freeways for all types of crashes with medium-high predictive certainty. They are:

Narrow lane widths to add lanes (applicable to urban freeway) Add shoulder rumble strips (applicable to both rural and urban freeway)

The digest mentions that no AMF exists for safety service patrol, which has become a very common countermeasure on many freeways as a way to reduce incidents and secondary crashes. The final report of this project will include a comprehensive summary of the best AMFs that are available at that time. A research titled “A Comprehensive Analysis of the Relationship between Real-Time Traffic Surveillance Data and Rear-End Crashes on Freeways” was prepared for the presentation at the TRB 2006 annual meeting (33). This paper attempts to develop a strategy to identify real-time traffic conditions prone to rear-end crashes using freeway loop detector data. The paper concludes that the rear end crashes may be grouped into two different segments/groups. The first group consists of rear end crashes that occur under extended congestion and the second group of crashes occurs with relatively free-flow conditions prevailing 5-10 minutes before the crash. The data comparison between two different groups revealed that group one crashes was associated with extended congestion indicated by high occupancy while group two crashes were associated with downstream speed differential and downstream on ramp traffic. The paper claims that 75 percent of the rear end crashes may be identified 5-10 minutes before their occurrence

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The University of Minnesota published a report titled “Identification and Simulation of a Common Freeway Accident Mechanism: Collective Responsibility in Freeway Rear-end Collisions” in April 2006 (34). In this study the researchers have obtained trajectory information of vehicles involved in rear end crash from video records. These trajectories were used to ascertain each driver’s speed, following distance, reaction time and braking rate. The researchers claim to have simulated what would have happened if certain driver reaction had been different, other variables remaining constant. The researchers claim to have established the following findings: “1. Short following headways by the colliding drivers were probable casual factors for the collisions, 2. for each collision at least one driver ahead of the colliding vehicles probably had a reaction time that was longer than his or her following headway, and 3. had the driver’s reaction time been equal to his or her following headway, the rear-end collision probably would not have happened.” A research study titled” Modeling the Probability of Freeway Rear-End Crash Occurrence’ published June 2006 (35) claims to have developed a model of freeway rear-end crash risk based on a modified negative binomial regression. The model considers a drivers response time distribution and applies a dual-impact structure accounting for the probability of a vehicle becoming an obstacle and the following vehicle’s reaction failure. The findings of this study include:

Higher VMT which is a generalized AADT was found to decrease the probability of a leading vehicle becoming an obstacle

Higher truck percentage per mile was found increase the probability of lead vehicle becoming an obstacle

Higher posted speed limit was found to decrease the probability of rear end collisions Narrow shoulder width was found to increase the probability of rear end crashes Probability of rear end crash is higher in the merge sections of the freeways.

A research study titled “Update and Enhancement of ODOT's Crash reduction Factors” was published in June 2006 (31). The main objective of this study was to update the list of crash reduction factors for Oregon Department of Transportation. ODOT has been using the current list of countermeasures since early 1990’s. The study lists the three distinct types of countermeasures and their crash reduction factors:

1. which are backed by robust research 2. with limited research and 3. discussion only (no research)

The Illinois DOT’s Guidelines to Counter Measure Effectiveness & Crash Reduction Factor effective November 2006 (29) has listed Raised Reflective Markers as countermeasure for nighttime freeway crashes of all types. The CRF is negative for ADT less than 20000 and is positive for ADT greater that 20000

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Ohio The Ohio Department of Transportation’s countermeasure effectiveness reduction factor was published in September, 1997, which was later revised in July, 2007 (9). The countermeasures for rear end crashes are listed as follows:

Lane use signs – overhead Install PTSWF sign/flasher [for approach speeds > 45 mph] Install left turn bay & extra pavement without signal Install left turn bay & extra pavement with signal Widen for left turn lane, including resurfacing Widen for right turn lane, including resurfacing Add left turn phase with new left turn lane Add left turn phase with existing left turn lane Install optically programmed heads Relocate driveway entrance

All the above listed had positive crash reduction factors for rear end crashes. The countermeasure - Install traffic signal - all types, had a negative crash reduction factor for rear end crashes though it was positive for other types of crashes Ohio Department of transportation published “Development of Crash Reduction Factors” in September 2005 (36). The report states that the main objective of the research effort was to develop CRFs for the seven types of improvements ranked by the ODOT as most important. They are as follows:

Add two-way left turn lane Install median barriers Remove/relocate fixed object Flatten slope, remove guardrail Flatten vertical curve Provide interchange lighting Close median opening

The CRFs were computed for only total crashes and injury/fatal crashes for all the above types of countermeasures. Rear end crashes were not specifically considered. The Ohio Department of Transportation, in an effort to develop a set of reliable base crash rates initiated a research project in 1998 with the University of Cincinnati. The study was titled “Rational Schedule of Base Accident Rates for rural Highways in Ohio, Phase I” (37). The researchers successfully developed a set of mathematical models to estimate base accident density/rate for non-intersections in rural highways in ODOT District 8. Phase II study (38) was completed in 2003 to develop a set of mathematical models to estimate base accident density/rate for non-intersections in rural highways in the remaining eleven ODOT districts. Crash base rate were developed for density and rate of different types of crashes including rear end crashes. Appropriate dependent variables were used in the development of the base rates. AID technique was employed in identifying a set of independent variables that had significant relationship with each dependent variable. The studies recommended means and standard deviations for each type of accidents type to be used as the method for

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calculating cash base rate. Regression equation was also developed in each of the research study which could be used as an additional tool for predicting the crash base rate. The results showed a strong relationship between rear end crash density and ADT. A small number of rear end crashes were also found to be associated with speed and population density. The AID tree is given in Appendix II. Another study to develop a set of mathematical models to estimate base crash rates for intersections in Ohio has been completed in December 2006(39). This study also employed similar methodologies that were used in the study to develop crash base rate for rural highways. Crash density was calculated for different types of intersections. A summary of the results showing the relationship between rear end crash density for different types of intersections and the independent variables is as follows:

Intersections With One Way Stop Sign - No Control Legs: Strong relationship between rear end crash density and ADT. A small number of rear end crashes were also found to be associated with number of left and through lanes

T Intersections with One Way Stop Sign - Stop Controlled Legs: Strong relationship between rear end crash density and ADT.

Two Way Stop Control Intersections- No Control Legs: Strong relationship between rear end crash density and ADT.

Two Way Stop Control Intersections- Stop Controlled Legs: Strong relationship between rear end crash density and ADT.

Flashing Beacon Control Intersections- No Control Legs: Strong relationship between rear end crash density and ADT.

For Flashing Beacon Control Intersections- Stop Controlled Legs: Strong relationship between rear end crash density and ADT.

Signalized Intersection Legs: Strong relationship between rear end crash density and ADT.

The AID Trees for each of the above mentioned intersections is given in Appendix II. Another research study to develop a set of crash base rate for freeways was completed in March 2007 (40). This study also employed similar methodologies that were used in the study to develop crash base rates for rural highways and intersections. The result showed a strong relationship between statewide freeway rear end crash density and ADT. A small number of rear end crash densities were also found to be associated with distance to interchange. Similarly, The result showed that a strong relationship existed between statewide freeway rear end crash rate and population density. A small number of rear end crash rate were also found to be associated with distance to interchange. The AID trees for statewide rear end crash density and rate are given in Appendix II. Summary Significant amount of research has been performed to understand rear end crashes on different types of roadways. Behavioral variables such as driver inattention influence of drug and alcohol, aggressive driving have been attributed to rear end crashes. Geometric and

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design variables such as number of lanes, curve characteristics, vertical grade, surface type, median type, turning lanes, shoulder width, lane width have been ascribed to have significant relationship with rear end crashes. Operation characteristics such as traffic control, red light camera, visibility of signs and markings have been recognized as having strong association with rear end crashes. Other roadway characteristics such as high congestion, work zones, slow or stopped traffic due to incidents also are found to have strong correlation with occurrence of rear end crashes. Several reduction strategies/factors exist, that address behavioral, geometric and design and operations characteristics of rear end crashes in different types of roadways such as intersections, rural and urban freeways and rural and urban highways. The condition of every state and every roadway segment within a state is inimitable. At the same time changes in roadway conditions could be very rapid. Many of the strategies that are being implemented by several agencies have been proven to have a high or medium level of certainty. There are also ongoing researches that look promising. Those strategies need to be examined and recommended if they are found compatible with the overall rear end collision strategy in Ohio.

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4.0 Further Review of Crash Reduction Factors with Medium to High

Level of Predictive Certainty for Rear End Collision Reduction Strategies

The NCHRP Report 617 titled “Accident Modification Factors for Traffic Engineering and ITS improvements” published in 2008 includes a comprehensive summary of the best AMFs that are available (41). “Remove a traffic signal” is one of the specific treatments with high level of predictive certainty for rear end crashes at intersections. The AMF for all types of crashes is calculated at 0.76 and the AMF for rear end crashes is calculated at 0.71 (41). Another specific treatment that has medium-high level of predictive certainty for different types of crashes which includes rear-end crash is “Convert to All-Way Stop Control.” The AMF for rear end crashes is 0.87 (41). “Add Exclusive left turn lanes” and “Add Exclusive right turn lanes” are two treatments that are defined as high level of AMF predictive certainty. This study does not specifically discuss about the percent reduction in rear end crashes or AMFs for rear end crashes. Numerous previous studies have indicated that rear end crashes constitute a high percentage of intersection crashes. The treatment discussed in this study, therefore could be as useful for rear end crashes. Further research targeted specific to rear end crashes may be warranted to gain a better insight. The AMFs given for different types of geometry for left-and right-turn crashes are as follows: Left-Turn Crashes: One Both Approach Approaches Rural Stop-Controlled Intersection (4-legs) 0.72 0.52 Rural Stop-Controlled Intersection (3-legs) 0.56 — Rural Signalized Intersection (4-legs) 0.82 0.67

Rural Signalized Intersection (3-legs) 0.85 — Urban Stop-Controlled Intersection (4-legs) 0.73 0.53

Urban Stop-Controlled Intersection (3-legs) 0.67 Urban Signalized Intersection (4-legs) 0.90 0.81 Urban Signalized Intersection (3-legs) 0.93

Right Turn Crashes:

Rural Stop-Controlled Intersection (4-legs) 0.86 0.74 Urban Signalized Intersection (4-legs) 0.96 0.92

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Fatal and Injury Intersection Accidents (all accident types) Rural Stop-Controlled Intersection (4-legs) 0.77 0.59

Urban Signalized Intersection (4-legs) 0.91 0.83 “Install Roundabouts” is another treatment that is defined as high level AMF predictive certainty. The AMFs for all types of accidents are calculated as followings: Roadway Type AMF Single Lane - Urban (prior control – two way stop control) 0.44 Single Lane - Rural (prior control – two way stop control) 0.29 Multilane – Urban (prior control – stop sign) 0.82 Single/Multilane – Urban (prior control - signal) 0.52 All sites All Crashes 0.65 “Convert Stop- Control to Yield Control” is one of the specific treatments with high level of predictive certainty for rear end crashes at intersections. The AMF for all types of crashes is given at 2.37 (41). “Install traffic signal at urban intersection” and “Install traffic signal at rural intersection” are two of the specific treatments with high level of predictive certainty for rear end crashes at intersections. The AMFs for “Install traffic signal at urban intersection” and “Install traffic signal at rural intersection” are given at 1.50 and 1.58 respectively. (41). “Install red light cameras” is another treatment with high level of predictive certainty. The AMF for rear end crashes with all type of severity is given at 1.15 and AMF for rear end crash with injury type severity is given at 1.24 (41).

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5.0: Possible Causes of Rear End Crashes and Their Reduction Strategies It seems that ODOT would greatly benefit if a “standard” set of possible causes of rear end crashes and corresponding general reduction strategies for these crashes could be developed and implemented on a statewide basis. Rear end crashes have exhibited different characteristics in different types of roadways and the causes of rear end crashes for these roadways may vary within a large number of contributing factors. Thus it is important to (a) determine the possible cause(s) for rear end crashes for the roadway or intersection under study and (b) to develop general strategies for reducing rear end crashes for each possible cause. Based on the authors’ research (44), a list of possible causes for rear end collisions for all types of roadways is provided below. 5.1 Possible Causes of Rear-End Crashes

• Absence of turning lanes • Inadequate advance warning intersection warning signs • Following too closely • Crossing pedestrians • Improper channelization • Improper passing maneuvers • Improper speed perception of right turning vehicles • Inadequate delineation • Inadequate directional guidance • Inadequate shoulders/shoulder drop-off • Insufficient left-turn storage length • Large number of turning vehicles • Lane drop • Lack of adequate gaps

-for side road traffic -for main line left turn

• Narrow lane width • Obstruction in or too close to roadway • Parking too close to intersection • Pavement condition • Restricted sight distance • Slippery pavement • Short turning radius • Stop & start condition at slip ramps of yield- merge condition • Drivers not aware of access points • Uncontrolled access • Yield sign control • Improper/Illegal parking Improper/absent signal coordination • Railroad crossing

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• Inadequate intersection identification • Inadequate signal timing or phasing • Lack of dilemma zone protection • Poor visibility of signals • Truck drivers hesitant to stop • Unwarranted signal

5.2 Reduction Strategies for Rear End Crashes Strategies for reducing rear end crashes can only be determined after possible causes of rear end crashes for specific sites are identified. The highway facility under study can be classified into the following groups:

1. Signalized intersections 2. Unsignalized intersections 3. Non-freeways and 4. Freeways

In the following tables, strategies for reducing rear end crashes are listed for each possible cause of the crash for each highway facility as described above.

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Table 3: Reduction Strategies for Rear End Crashes at Signalized Intersections Possible Causes of Rear End Crashes

Reduction Strategies for Rear End Crashes

Slippery pavement • Overlay pavement • Provide adequate drainage • Groove pavement • Provide “slippery when wet” signs • Clean up road surface i.e. gravel, sand, soil, etc • Improve snow and ice control measures

Absence of Turning Lanes • Provide turning lanes • Increase turning radii

Crossing pedestrians • Install/improve signing or marking for pedestrian crosswalks

• Reroute/prohibit pedestrian traffic • Construct pedestrian bypass/overpass • Install heads and buttons if warranted • Install pedestrian phase

Improper speed perception of right turning vehicles

• Prohibit/right turns on red from side streets • Install/Improve acceleration lane • Install/improve pavement markings

Improper/absent signal coordination

• Coordinate signals • Optimize signal coordination

Inadequate directional guidance

• Install additional pavement markings(dotted lines)/channel lines

• Install/improve lane use control signs • Improve turn radii • Increase enforcement • Install/improve directional signing

Inadequate intersection identification

• Install/improve road name signs • Install advance road name signs

Inadequate signal timing or phasing

• Adjust amber phase • Provide progression through a set of signalized

intersections, if available • Provide/adjust all-red clearance • Adjust signal timing or phasing

Insufficient left-turn storage length

• Lengthen left-turn storage

Lack of dilemma zone protection

• Provide dilemma zone protection

Lack of improper vehicle detection or malfunctioning loop detectors

• Relocate/modify vehicle detectors • Provide adequate maintenance of loop detectors • Install/improve dilemma zone loop detector configuration • Provide vehicle detection

Large number of turning vehicles

• Create left or right turn lanes • Prohibit turns • Increase turn radii • Provide special phase for turning traffic • Widen roadway • Channelize intersection • Retime signal

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• Provide turning guidelines • Provide dual turning lanes • Channelize intersection • Retime signal

Poor visibility of signals • Install/ improve advance warning signs • Install/improve overhead signals • Install/improve visors • Install/improve back plates • Relocate signals • Add additional signal heads • Remove obstacles • Provide flashers on advance warning devices • Use programmable heads • Provide dilemma zone protection • Adjust/re-aim signal head • Install higher watt signal

Restricted sight distance • Remove obstacles • Provide adequate channelization • Provide phase for left turning traffic • Install/improve warning signs • Provide adequate sight distance • Restrict parking near intersection • Restrict/prohibit turns • Optimize stop bar placement to accommodate turning

traffic • Install supplemental heads

Short turning radius • Provide adequate turning radii • Locate stop bars to accommodate turning traffic • Widen intersection • Install “Stop here on Red Signs”

Stop & start condition at slip ramps of yield- merge condition

• Change to stop condition • Provide/improve acceleration lane • Remove ramp • Provide adequate roadway geometry

Truck drivers hesitant to stop • Provide/adjust dilemma zone protection • Add delay to side road detection to minimize frequency

of signal changing • Provide additional all red clearance

Unwarranted Signal • Remove signal Improper channelization • Improve channelization Improper passing maneuvers • Install/improve no-passing markings

• Extend/modify existing passing zones • Increase enforcement • Install/upgrade warning signs

Inadequate advance warning intersection warning signs

• Install/upgrade advance intersection warning signs • Install flashers on advance warning devices

Inadequate delineation • Optimize stop bar placement to accommodate turning traffic

• Install/improve raised pavement markers • Refurbish markings • Provide double-painting • Improve/install pavement markings • Install/upgrade delineation

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• Install/upgrade advance warning signs Inadequate shoulders/shoulder drop-off

• Correct shoulder drop-off • Improve roadway shoulders • Install/improve advance warning signs(interim)

Lane drop beyond Intersection

• Drop lane at or before intersection • Add complete lane beyond intersection • Install/improve signing • Install improve pavement markings

Narrow lane width • Provide adequate lane width • Install/widen paved shoulder

Obstruction in or too close to roadway

• Remove obstacles • Warn of obstructions • Mark obstructions • Install barrier curbing • Install breakaway features to light poles, sign post etc • Project objects with guard rail (if warranted) • Install crash cushioning device

Parking too close to intersection

• Post parking restrictions near intersections

Pavement condition • Perform road surface repair • Install warning sign (interim)

Uncontrolled access at intersection

• Eliminate, consolidate or relocate drives • Install service roads • Provide curb & gutter section to control/define access

points • Reduce width of access

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Table 4: Reduction Strategies for Rear End Crashes at Unsignalized Intersections Possible Causes of Rear End Crashes


Absence of Turning Lanes • Provide turning lanes • Increase dual turning lanes

Crossing pedestrians • Install/improve additional signing • Improve horizontal/vertical alignment • Install/improve intersection control beacons • Install/improve road name signs • Improve sight distance and/or remove sight

obstruction(s) • Install/improve rumble strips • Install/improve street lighting

Improper channelization • Improve channelization Improper passing maneuvers • Install/improve no-passing markings



• Install/Improve acceleration lane • Install/improve pavement markings

Inadequate advance warning intersection warning signs

• Install/upgrade advance intersection warning signs • Install flashers on advance warning devices

Inadequate delineation • Optimize stop bar placement to accommodate turning traffic

• Install/improve raised pavement markers • Refurbish markings • Provide double-painting • Improve/install pavement markings • Install/upgrade delineation • Install/upgrade advance warning signs

Inadequate directional guidance

• Install/improve directional signing • Install additional pavement markings • Install/improve lane use control signs • Increase enforcement • Improve turn radii

Inadequate shoulders/shoulder drop-off

• Correct shoulder drop-off • Improve roadway shoulders • Install/improve advance warning signs (interim)

Insufficient left-turn storage length

• Lengthen left-turn storage • Improve lane use signs

Lack of adequate gaps -for side road traffic -for main line left turn

• Provide traffic signal if warranted • Provide multi-way stop signs

Lane drop beyond Intersection

• Drop lane at or before intersection • Add complete lane beyond intersection • Install/improve signing • Install improve pavement markings


• Create left or right turn lanes • Prohibit turns • Increase turn radii • Provide traffic signal

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• Provide multi-way stop signs • Widen roadway • Channelize intersection

Narrow lane width • Provide adequate lane width • Install/widen paved shoulder


• Remove obstacles • Warn of obstructions • Mark obstructions • Install barrier curbing • Install breakaway features to light poles, sign post etc • Project objects with guard rail(if warranted) • Install crash cushioning device

Parking too close to intersection

• Post parking restrictions near intersections


Restricted sight distance • Remove obstacles • Provide adequate channelization • Install/improve active warning signs • Provide adequate sight distance • Restrict parking • Restrict/prohibit turns • Provide turn lanes

Short turning radius • Provide adequate turning radii • Locate stop bars to accommodate turning traffic • Widen intersection

Slippery pavement • Overlay pavement • Provide adequate drainage • Groove pavement • Provide “slippery when wet” signs • Clean up road surface i.e. gravel, sand, soil, etc • Improve snow and ice control measures • Flatten steep grades


• Change to stop condition • Provide/improve acceleration lane • Provide overlap phase • Remove ramp • Add right turn lane • Provide adequate roadway geometry

Uncontrolled access at intersection

• Eliminate, consolidate or relocate drives • Install service roads • Provide curb & gutter section to control/define access

points • Reduce width of access

Yield Sign Control • Install stop signs • Change geometrics • Improve sight distance characteristics

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Table 5: Reduction Strategies for Rear End Crashes at Non-Freeways Possible Causes of Rear End Crashes


Absence of Turning Lanes • Provide turning lanes • Provide Two Way Left Turning Lane

Crossing pedestrians • Install/improve signing or marking for pedestrian crosswalks

• Reroute/prohibit pedestrian traffic • Construct pedestrian bypass/overpass • Install signal if warranted

Drivers not aware of access points

• Install/improve signing • Improve horizontal/vertical alignment • Install sight distance • Provide flashers on advance warning devices • Identify access points • Right in right out movements at access point • Close/relocate/consolidate drives

Following too closely • Driver education of safe driving practices –TV commercials

• Provide headway maintenance system • Increase capacity • Provide climbing lane

Improper illegal parking • Increase enforcement • Prohibit parking • Create off street parking • Post parking restrictions

Improper/absent signal coordination

• Coordinate signals • Optimize signal coordination

Inadequate delineation • Improve/install pavement markings • Install/upgrade delineation • Install/upgrade advance warning signs • Optimize driveway stop bar placement to accommodate

turning traffic • Install/improve raised pavement markers • Refurbish markings • Provide double-painting

Uncontrolled access • Close/ relocate drives • Provide curb & gutter section to control/define access

points • Reduce width of access • Install service roads




• Correct shoulder drop-off • Improve roadway shoulders • Install/improve advance warning signs (interim) • Install/improve delineation

Lack of adequate gaps -for side road traffic -for main line left turn

• Provide traffic signal if warranted • Provide Lt lane or right side loop ramp at grade

separator Lane drop • Drop lane at or before intersection

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• Add complete lane beyond intersection • Install/improve signing • Install improve pavement markings


• Create left or right turn lanes • Prohibit turns • Increase turn radii • Change TWLTL to exclusive LT • Widen roadway

Narrow lane width • Provide adequate lane width • Install/widen paved shoulder • Lower speed limit • Advance warning of narrow lane

Railroad crossing • Install/improve warning signs • Provide adequate sight distance • Repair/replace crossing • Remove hump

Restricted sight distance • Remove obstacles • Provide adequate channelization • Install/improve active warning signs • Provide adequate sight distance • Restrict parking near intersection • Restrict/prohibit turns • Optimize stop bar placement to accommodate turning

traffic Slippery pavement • Overlay pavement

• Provide adequate drainage • Groove pavement • Provide “slippery when wet” signs • Clean up road surface i.e. gravel, sand, soil, etc • Improve snow and ice control measures

Improper channelization • Improve channelization Improper passing maneuvers • Install/improve no-passing markings



• Remove obstacles • Warn of obstructions • Mark obstructions • Install barrier curbing • Install breakaway features to light poles, sign post etc • Project objects with guard rail (if warranted) • Install crash cushioning device



• Change to stop condition • Provide/improve acceleration lane • Provide overlap phase • Remove ramp • Add right turn lane • Provide adequate roadway geometry

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Table 6: Reduction Strategies for Rear End Crashes at Freeways Possible Causes of Rear End Crashes


Drivers not aware of exit/entry points

• Install/improve signing • Improve horizontal/vertical alignment • Provide flashers on advance warning devices • Identify access points

Following too closely • Driver education of safe driving practices –TV commercials

• Provide headway maintenance system • Increase capacity • Provide climbing lane

Inadequate delineation • Improve/install pavement markings • Install/upgrade delineation • Install/upgrade advance warning signs • Install/improve raised pavement markers • Refurbish markings • Provide double-painting

Improper speed perception of merging vehicles



• Correct shoulder drop-off • Improve roadway shoulders • Install/improve advance warning signs (interim) • Install/improve delineation

Lack of adequate gaps • Provide ramp meters • Provide advance warning signs

Large number of exiting vehicles

• Create left or right turn lanes • Increase turn radii • Widen roadway and exit ramps

Narrow lane width • Provide adequate lane width • Install/widen paved shoulder • Lower speed limit • Advance warning of narrow lane

Slippery pavement • Overlay pavement • Provide adequate drainage • Groove pavement • Provide “slippery when wet” signs • Clean up road surface i.e. gravel, sand, soil, etc • Improve snow and ice control measures

Improper channelization • Improve channelization Pavement condition • Perform road surface repair

• Install warning sign (interim) Stop & start condition at slip ramps of yield- merge condition

• Change to stop condition • Provide/improve acceleration lane • Remove ramp • Provide adequate roadway geometry

Heavy congestion related to recurrent traffic conditions, incidents, or work zones

• Provide advance real time traffic information • Provide advance warning signs with/without flashers

Improper perception of traffic conditions at merge section of

• Provide advance real time traffic information • Install/Improve merge lane

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freeway • Improve acceleration lane • Install ramp meter

Existence of vertical or horizontal sight distance constraint

• Improve vertical or horizontal visibility/sight distance • Advance warning signs with/without flashers

Narrow shoulder width • Provide adequate shoulder width

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6.0: Data Collection and Analysis: The primary objective of this task was to examine the required rear end crash data and the data relating to countermeasures applied to signalized and unsignalized intersections, freeways and non-freeways. 6.1: Data Collection: At the request of the researchers, the Ohio DOT provided the following data:

1. Crash data (1997- 2006) – work zones were excluded. 2. Countermeasures completed at different types of roadways (1999 - 2004).

This study attempted to examine the above-mentioned data for all intersections, freeways and non-freeways where the countermeasures were implemented. 6.2: Data Compilation: The Excel file consisting of countermeasure data provided by ODOT contained both individual and multiple countermeasures at roadway segments. Only sites with individual countermeasures were chosen for this study as a review of past literature revealed (e.g. NCHRP Research Digest 299) that no substantial research has yet been done on effect of multiple countermeasures at a single location. The examination for the data was completed in the following steps: Task 1: The first task completed by the researchers was the separation of the rear end crash data from the crash data of all types provided by the ODOT. Task 2: The second task consisted of separating the rear end crash data for each year. Task 3: During the third task, the rear end crash data was combined into intervals of three year periods. For example, a single Microsoft Access file of combined rear end crash data for 1997-1999 was created to analyze the “before” crash data for the countermeasures completed in 2000. A single Microsoft Access file of combined rear end crash data for 2001-2003 was created to analyze the “after” crash data for the countermeasures completed in 2000. Task 4: The fourth task was to merge the “before” 3-year rear end crash data and “after” 3- year rear end crash data with the rear end crash data for the corresponding year on which the countermeasures were applied. Microsoft Access program, Structured Query Language and Microsoft Excel were used. Task 5: In the fifth task, the merged database was separated into three different subgroups: intersections, freeways and non-freeways. A master file for each specific site on which the countermeasure was implemented was created, which consisted of the “before” and “after” rear end crash data for the year of implementation. An example of the master file for countermeasures on interstate freeways implemented in 2004 is given in Table 7. A complete set of the data is given in Appendix I.

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Table 7. Simple Before Study for Countermeasures Employed on Intersections in 2004 Dist NLF ID Begin

Log End Log

Countermeasure Before (# of rear end crashes - 2002 and 2003)

After (# of rear end crashes 2005 and 2006)

Percent Change

2 SLUCIR00280**C 4.91 5.1 widen to six lanes 2 0 100.00 4 SSUMIR00076**C 10 12 Extend channel line

for I-76 EB to I-77 SB ramp

168 173 -2.98

7 SMOTIR00075**C 3.74 20.4 2003 Added Thru-75-Arrow

824 737 10.56

7 SMOTIR00075**C 10 12 03 - Micro-surface to correct skid numbers.

72 81 -12.50

8 SBUTIR00075**C 0 6.72 Major widening PID 10751 and study PID 75971 should address issues

453 352 22.30

8 SHAMIR00071**C 7.53 8.03 abb, Add signs on Ramps and exit panels

21 23 -9.52

8 SHAMIR00071**C 9.82 10.1 Add speed limit signs

15 12 20.00

8 SHAMIR00071**C 12 14 Rumble strips on shoulders.

93 119 -27.96


186 183 1.61


180 97 46.11

8 SHAMIR00071**C 18 19.9 Rumble strips on shoulders.

187 141 24.60

8 SHAMIR00074**C 5.73 6.26 Signs/Turnarounds, Signs up 7/13/99

2 2 0.00

8 SHAMIR00074**C 9.2 9.33 PID 75730 to reconstruct ramps should address issues

2 3 -50.00

8 SHAMIR00074**C 16 18 Rumble strips on new pavement

56 73 -30.36

8 SHAMIR00074**C 17.4 17.7 PID 78082 ramp meters should address issues

10 10 0.00

8 SHAMIR00074**C 18 18.8 PID 78082 to add ramp meters should address issues

34 33 2.94

8 SHAMIR00074**C 18.5 19 continue with projects to redesign interchange and install ramp metering

52 44 15.38

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8 SHAMIR00074**C 19.2 19.5 PID 76257 to reconstruct interchange and PID 78082 to install ramp meters should address issues

18 10 44.44

8 SHAMIR00275**C 18.6 20.6 Remove unpaved crossovers.

63 86 -36.51


499 375 24.85

8 SHAMIR00275**C 24 24.6 widening project PID 22386 should address safety issues

60 69 -15.00

8 SHAMIR00275**C 30.7 31.6 PID 20128 to add aux lane from 42 to RHH should address issues

54 29 46.30

8 SWARIR00075**C 10 12.2 PID 10754 widening to the MOT Co line should address issues

22 20 9.09

12 SCUYIR00090**C 14.5 14.9 Install rumble strips 36 34 5.56

Task 6: This study attempted to perform comprehensive statistical tests for each file consisting of the “before and “after” rear end crash data and countermeasures implemented at the site. The objective of this task was to compute the crash reduction factors for rear end collisions for these roadway facilities. However, this task could not be accurately performed because of the limitations in the ODOT countermeasure data. Before-and-after studies are primarily done for evaluating the effectiveness of countermeasures and calculating crash reduction factors. Several Before-After designs are available:

(1) Simple Before/After Design: The basic before-and-after design is the Simple Before/After design. It evaluates a situation before and after a countermeasure is implemented. This design is found to have many drawbacks and is most often not used by safety researchers. The results, particularly the crash reduction factors based on Simple Before/After Design, will have low level of predictive certainty, if any, for collision strategies.

(2) Before/After with randomized control groups In this design, sites with similar characteristics with likelihood of implementation of countermeasures are assigned randomly to either control group or treatment group. All the sites have thus, equal chance of falling into either of the groups. However, an improvement measure is implemented only in the treatment group and no treatment is done in the control group. Measurement before and after treatment is done in the

52

treatment group. Measurement before and after without treatment is done in the control group and the results are evaluated. This design has been found to reduce biasness and improve the accuracy of estimation.

(3) Before/After with comparison groups The Before/After design with comparison group could be better suited to this study since it could utilize ODOT historical data for roadway facilities where improvements were completed in the past. The only difference between the preceding design and this design is that the groups are not assigned on a random basis in this design. The measurement criteria are the same. This design is more appealing and practical to this study as sites with historical records (for example, ODOTs crash data for a particular site) can be chosen even after countermeasures are implemented. The before and after results in control groups are evaluated and compared with before and after results of the treatment group. For each site that is selected for study, the traffic, roadway and rear end crash data for 3 years prior to and 3 years after the improvement can be used (42, 43). The roadways can be classified by different types, which include signalized intersections, unsignalized intersections, non-freeways and freeways. The selection of the sites can be based on the above criteria and can be grouped into control and treatment groups. Data permitting, a sizable number of sites can be selected for each group for minimizing statistical bias in the analysis.

Our examination of the ODOT data revealed that it was not possible to determine the effectiveness of the countermeasures and calculate crash reduction factors by using the Before/After Comparison Groups Design for several reasons: 1: In most case the countermeasures were not specific enough to be included in the study. For example, the freeway countermeasures implemented in 2002 was follows:

• Add lanes • Mill to improve skid resistance • Epoxy pavement markings • Improve Exit Ramp • Enhance warning signs for exit loop ramp • Interchange improvements • Include Portable Message Board in construction plans to alert traffic to slower

moving traffic ahead • Install YIELD sign for WB ramp • Install 2 merge warning signs, relocate 3, install 1 Yield sign • Section currently under total reconstruction • Add Lane project to increase interstate capacity. • Milled to improve skid resistance • Improve signing and pavement markings • Capacity addition

Another example of the intersection countermeasures employed in the year 2003 was as follows:

• Rehabilitate roadway

53

• Reconstruct intersection, installing LT lanes and RT lane and increasing approach radii; Signal upgrade addition of turn phases.

• New interchange • Construct offset LT lanes on SR82, LT lanes on SR7 and RT lane on SR7 SB

approach. • Widening and Increasing Intersection Radius • Replacing 2 Traffic Signals • Removal of parking on street

The above countermeasures are not uniform and lack precise definitions. Most of the countermeasures suggest a broad range of treatments, thus limiting the execution of quantitative analysis. 2: A reasonable number of sites with the same countermeasures implemented during the analysis period are necessary for classifying them into control and treatment groups. The ODOT data did not provide the possibility for grouping the available sites in this manner. 3: It was determined that any attempt to determine the effectiveness of countermeasures and calculate crash reduction factors would only lead to misleading and inaccurate results. Hence, the researchers requested ODOT to provide additional data that will be conducive to the determination of crash reduction factors. 6.3 Request for Data To summarize, the researchers worked on the following data that were previously received from ODOT:

1. Crash data (1997- 2006) excluding work zone crashes 2. Countermeasures completed at different types of roadways (1999 - 2004).

Based on the data received from ODOT, the researchers had so far isolated the sites that were applied with single treatments. Thereafter, the researchers categorized the sites into different groups with sites that appeared to have been applied with similar countermeasures. However, it should be noted that most of these countermeasures listed in ODOT data are described in a broad manner without any specificity. It is necessary, therefore, to further investigate these sites and countermeasures to determine if these data are suitable for calculating crash reduction factors. The eighteen countermeasures listed in ODOT data are shown in Table 8.

Table 8. Countermeasures Listed in ODOT Data

1 Channelization and/or Turning Lanes 2 Access Management / Raised Median 3 Micro-surface to correct skid numbers or similar countermeasures 4 Resurface pavement or similar countermeasures 5 Lanes Added to Traveled Way 6 Sight Distance Improvements 7 Add speed limit signs or similar countermeasures 8 Signing improvements or similar countermeasures 9 Traffic Signal Installation or similar countermeasures 10 Improved signal coordination or similar countermeasures 11 Rumble strips on shoulders or similar countermeasures 12 Add lanes or similar countermeasures 13 Install 4-way stop and advance warning signage or similar

countermeasures 14 New interchange or similar countermeasures 15 Hill repaved for skid resistance or similar countermeasures 16 Widened Traveled Way or similar countermeasures 17 Reconstruct ramps should address issues or similar countermeasures 18 Add median should address issues or similar countermeasures

In order to further investigate the countermeasures and the sites where these countermeasures were applied, the researchers generated the 18 tables (not included in this report) where each table provided a list of sites where a countermeasure was applied. Each table contained the following fields:

1. District 2. NLF_ID 3. County 4. Route 5. Begin Log 6. End Log 7. Countermeasure 8. Completion Date

Further investigation needed to be done to fully understand what specific countermeasure was actually used at each site. For example, the countermeasure listed as “channelization and/or turning lanes” did not fully explain what kind of channelization was used or if a left turn lane, right turn lane or both right turn and left turn lanes were added. Without any specific information, anything was open to assumption. To facilitate further research, we requested ODOT to help us in getting in-depth data for each countermeasure and roadway site as listed in the above-mentioned tables. Our data needs were summarized in Tasks 1 thru 5 as shown below.

54

55

1. Task 1. For each site listed in each table, we requested ODOT to help us in determining in further specific terms and details what countermeasure was exactly used at each site. This information needs to be reviewed and finalized for all sites.

2. Task 2. Based on the outcome of Task 1, the researchers would prepare a revised list of countermeasures and sites for further investigation.

3. Task 3. For the sites included in the revised list, the researchers would request ODOT to provide the geometric features of each site before and after the countermeasures were applied. The researchers would also request ODOT to provide the AADT data for each site before and after the countermeasures were applied.

4. Task 4. Based on the information in Task 3, the researchers would further revise the list of countermeasures and sites so that sites with similar geometric features and AADT were grouped together for each countermeasure.

5. Task 5. Based on the information in Task 4, the researchers would request ODOT to provide them with a list of other sites in the State of Ohio that have similar geometric features, AADT and crash experience but where no countermeasures were applied during the before and after periods. The purpose of this effort is to create comparison groups for further analysis which will allow the researchers to perform the remaining work and calculate crash reduction factors.

In the researchers’ opinion, the most important item was to begin with Task 1, which required a detailed investigation of the countermeasure performed at each site. The knowledge gained from completing Task 1 would allow them to work on Task 2, Task 3 etc leading them toward the calculation of accident reduction factors.

56


57

7.0: Conclusions This study performed a review of the past literature on reduction strategies for rear end crashes. The review has shown that research on crash reduction factors and accident modification factors for rear end collision strategies is quite limited. The ODOT data received by the researchers had severe limitations for analyzing the effectiveness of countermeasures for rear end collision strategies. To facilitate further research, the researchers requested ODOT to help them in getting in-depth data for each countermeasure and roadway site. The data needs were summarized in a letter dated August 19, 2008 to ODOT. ODOT, however, decided not to proceed ahead with this research as it required the dedication of district resources that were not currently available. ODOT internally discussed the possibility of breaking the project into smaller, more manageable pieces, but believed this approach would not yield results that would be statistically significant. In addition, there were also several national projects underway which would limit this project’s benefits. In view of the above circumstances, ODOT decided to terminate the contract for this project and all work stopped.

58


59

8.0: Reference

1. National Transportation Statistics 2007, Bureau of Transportation Statistics, Research and Innovative Technology Administration. http://www.bts.gov/publications/national_transportation_statistics/2007/index.htm, Accessed Dec. 28, 2008.

2. Facts, Statistics and Data. Federal Highway Administration, U.S. Department of Transportation. http://safety.fhwa.dot.gov/facts/ , Accessed Nov. 28, 2007.

3. Status of NHTSA’s Rear-End Crash Prevention Research Program. National Highway Traffic and Safety Administration, U.S. Department of Transportation. http://www-nrd.nhtsa.dot.gov/pdf/nrd-01/esv/esv19/05-0282-O.pdf, Accessed Nov. 28, 2007

4. Crash Information. Department of Public Safety. http://www.publicsafety.ohio.gov/crashes/crash_facts.asp, Accessed Dec. 28, 2008

5. Greg Murphy & Jennifer Townley. Strategies for Improving Strategies Safety and Mobility on Ohio Roads. http://www.otecohio.org/presentations/OTECpresentations/Se15/JT_GM-Safety.pdf, Accessed June 28, 2007

6. Road way Safety and Mobility. Ohio Department of Transportation http://www.dot.state.oh.us/planning/Safety/GoalsandObjectives.htm, Accessed Nov. 28, 2007

7. National Review of Highway Safety Improvement Program, US Department of Transportation, http://safety.fhwa.dot.gov/media/hsip_final.htm, Accessed Nov. 28, 2007

8. Estimates of Countermeasure Effectiveness Reduction (CRF) Factors. Road way Safety and Mobility. Ohio Department of Transportation http://www.dot.state.oh.us/roadwaysafety/PDF_Files/Crash%20Reduction%20Factors%20Table%202004.pdf. Accessed Nov 28. 2004

9. Estimates of Countermeasure Effectiveness Reduction (CRF) Factors. Office of Systems Planning and Program Management, The Ohio Department of Transportation. http://www.dot.state.oh.us/planning/Safety/2006data/Crash%20Reduction%20Factors%20FY2008.PDF, Accessed Nov. 28, 2007

10. Safety Study Guidelines. Office of Systems Planning and Program Management, The Ohio Department of Transportation. Accessed Nov. 28, 2007 http://www.dot.state.oh.us/planning/Safety/PDF_Files/SafetyStudyGuidlines.pdf

11. Rate of Return Analysis. Office of Systems Planning and Program Management, The Ohio Department of Transportation. Accessed Nov. 28, 2007 http://www.dot.state.oh.us/planning/Safety/SafetyPrograms.htm

12. Timothy L. Brown, John D. Lee, Daniel V. McGehee. Attention Based Model of Driver Performance in Rear End Collisions. In Safety and Human Performance. Transportation Research Board 2000 Annual Meeting CD ROM, Washington D.C., Jan 9-13, 2000.

13. James G. Strathman, Kenneth J. Duecker, Jihong Zhang and Timothy Williams. Analysis of Design Attributes and Crashes on the Oregon Highway System. Oregon Department of Transportation, August 2001.

http://safety.fhwa.dot.gov/facts/

http://www-nrd.nhtsa.dot.gov/pdf/nrd-01/esv/esv19/05-0282-O.pdf

http://www.otecohio.org/presentations/OTECpresentations/Se15/JT_GM-Safety.pdf

http://www.dot.state.oh.us/planning/Safety/GoalsandObjectives.htm

http://safety.fhwa.dot.gov/media/hsip_final.htm

http://www.dot.state.oh.us/roadwaysafety/PDF_Files/Crash Reduction Factors Table 2004.pdf

http://www.dot.state.oh.us/roadwaysafety/PDF_Files/Crash Reduction Factors Table 2004.pdf

http://www.dot.state.oh.us/planning/Safety/2006data/Crash Reduction Factors FY2008.PDF

http://www.dot.state.oh.us/planning/Safety/2006data/Crash Reduction Factors FY2008.PDF

http://www.dot.state.oh.us/planning/Safety/2006data/ROR Tool FY2008.xls

http://www.dot.state.oh.us/planning/Safety/SafetyPrograms.htm

60

http://www.oregon.gov/ODOT/TD/TP_RES/docs/Reports/AnalysisDesignAtt.pdf. Accessed Nov. 28, 2007.

14. Takashi Nakatsuji, Mansour Hadji Hosseinlou, Akira Kawamura, and Yuki Onodera. Taking Tire Slip Ratio into Account and Estimating Friction Coefficients in Rear-End Collisions on Winter Roads. In Maintenance. CD ROM Transportation Research Record, Transportation Research Board, Washington, D.C. 2001 pp. 97 -103.

15. Hariharan Krishnan, Scott Gibb, Aaron Steinfeld, and Steven Shladover. Rear-End Collision–Warning System Design and Evaluation via Simulation. In Safety and Human Performance. CD ROM Transportation Research Record, Transportation Research Board, Washington, D.C. 2001 pp. 52 -60.

16. W-Project Crash Reduction Information. North Carolina Department of Transportation, 2002. http://www.ncdot.org/doh/PRECONSTRUCT/traffic/Safety/ses/project_guide/regionalfactors110206.pdf. Accessed Nov.28, 2007

17. Joan Shen and Albert Gan. Development of Crash Reduction Factors: Methods, Problems, and Research Needs. Transportation Research Board 2003 Annual Meeting CD ROM, Washington D.C., Jan 12-16, 2003.

18. Mohamed A. Abdel-Aty and Hassan T. Abdelwahab. Configuration Analysis of Two-Vehicle Rear-End Crashes, Transportation Research Board 2003 Annual Meeting CD ROM, Washington D.C., Jan 12-16, 2003.

19. Santokh Singh. Driver Attributes and Rear-end Crash Involvement Propensity, Research and Development, NHTSA, US Department of Transportation, March 2003. http://www-nrd.nhtsa.dot.gov/pdf/nrd-30/NCSA/Rpts/2003/809-540.pdf, Accessed June 22,2004

20. Campbell, Brittany N., Smith, John D.and Najm, Wassim G. Examination of Crash Contributing Factors Using National Crash Databases. Research and Development, NHTSA, US Department of Transportation, October 2004. http://www-nrd.nhtsa.dot.gov/pdf/nrd-12/HS809664.pdf, Accessed Nov. 28, 2007.

21. Agent, Kenneth R Agent and Stamatiadis, Nikiforos. Development of Crash Reduction Factors. Kentucky Transportation Center, University of Kentucky, June 1997. http://www.ktc.uky.edu/Reports/KTC_96_13.pdf. Accessed Nov. 28, 2007.

22. Vermont Strategic Highway Safety Plan, Vermont. Gov, December 2006. http://www.atssa.com/galleries/default-file/VT_SHSP.pdf, Accessed March 28,2007

23. NCHRP Synthesis 310, Impact of Red Light Camera Enforcement on Crash Experience A Synthesis of Highway Practice. Transportation Research Board. 2003. http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_syn_310.pdf. Accessed Nov. 28, 2007

24. Strategic Highway Safety Plan, National Cooperative Highway Research Program. 2003. http://safety.transportation.org/guides.aspx. Accessed Nov 28,2007

25. Garber, Nicholas J., Miller, John S., Eslambolchi, Saeed, Khandelwal, Rahul, Mattingly, Kimberly M., Sprinkle, Kristin M., Wachendorf, Patrick L. An Evaluation of Red Light Camera (Photo-Red) Enforcement Programs in Virginia: A Report in Response to a Request by Virginia’s Secretary Of Transportation. Virginia Department of Transportation, University of Virginia, January 2005. http://www.thenewspaper.com/rlc/docs/05-vdot.pdf, Accessed Nov. 28, 2007

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26. Richards, C.M., Michaels, E.F., Campbell, J. Attitudes and Behaviors at Intersections and Potential Effectiveness of Engineering Countermeasures Publication FHWA-HRT-05-078. Office of Safety Research and Development, Federal Highway Administration, November 2005. http://www.tfhrc.gov/safety/pubs/05078/05078.pdf. Accessed Nov. 28, 2007.

27. Gan, Albert and Shen, Joan. Update of Florida Crash Reduction Factors and Countermeasures to Improve the Development of District Safety improvement Projects Lehman Center of Transportation Research, Department of Civil and environmental Engineering, Florida International University. April 2005. http://lctr.eng.fiu.edu/Documents/CRFFinalReport.pdf. Accessed Nov. 28,2007

28. Research Results Digest 299, National Cooperative Highway Research Program, November 2005. http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rrd_299.pdf, Accessed Nov. 28, 2007

29. Monsere,, Christopher M., Bertini,, Robert L., Breakstone,Aaron, Bonner,Carolyn, Bosa, Peter,de la Houssaye, David, Horowitz, Zachary, and Hunter-Zaworski, Kate. Update and Enhancement of ODOT's Crash Reduction Factors, Oregon Department of Transportation. June 2006. http://www.oregon.gov/ODOT/TD/TP_RES/docs/Reports/Crash_Reduction_Factors.pdf, Accessed Nov. 28, 2007

30. Guidelines to Counter Measure Effectiveness & Crash Reduction Factor Illinois Comprehensive Highway Safety Plan, Illinois Department of Transportation. November 2006. http://www.dot.state.il.us/safetyEng/Appendix%20E.pdf, Accessed Nov. 28,2007

31. Wiles, Poonam B., Cooner, Scott A., Walters, Carol H. and Pultorak and Edward J. Advance Warning Of Stopped Traffic On Freeways: Current Practices And Field Studies Of Queue Propagation Speeds. Publication FHWA/TX -03/4413-1. Texas Department of Transportation, June 2003.

32. Wiles, Poonam B., Cooner, Scott A., Rathod, Yatin and Wallace Diane G. Advance Warning Of Stopped Traffic on Freeways: Field Studies of Congestion Warning Signs. Publication FHWA/TX -05/0-4413-2. Texas Department of Transportation, March 2005

33. Pande, Anurag and Abdel_Aty Mohamed. A Comprehensive Analysis of the Relationship between Real-Time Traffic Surveillance Data and Rear-End Crashes On Freeways. TRB 06-0016, Manuscript prepared for the presentation at the TRB annual meeting. November 2005. http://www.mdt.mt.gov/research/docs/trb_cd/Files/06-0016.pdf .Accessed March 23, 2004

34. Davis, Gary A. Swenson, Tait. Identification and Simulation of a Common Freeway Accident Mechanism: Collective Responsibility in Freeway Rear-end Collisions. Department of Civil Engineering, University of Minnesota, April 2006. http://www.cts.umn.edu/pdf/CTS-06-02.pdf. Accessed Nov. 28,2007

35. Kim, Joon-Ki, Wang Yinhai and Ulfarsson, Gudmundur F. Modeling The Probability Of Freeway Rear-End Crash Occurrence. Paper Submitted to Journal of Transportation Engineering. June 2006. http://www.uwstarlab.org/STARLab_Papers/2006_JTE_FRE.pdf, Accessed Nov. 28, 2007

36. Hovey, Peter W.and Chowdhury, Mashrur. Development of Crash Reduction Factors. Safety Research Document, Ohio Department of Transportation September 2005. http://www.dot.state.oh.us/research/2005/Safety/14801-FR.pdf. Accessed Nov.28, 2007.

37. Pant, P.D., Liu Y. and Vasisht G. Rational Schedule of Base Accident Rates for Rural Highways in Ohio (Phase-I). Publication FHWA/OH -2000/003. Ohio Department of Transportation, January 2000.

38. Pant P.D., Rajagopal, A. and Cheng, Y. Rational Schedule of Base Accident Rates for Rural Highways in Ohio (Phase-II). Publication FHWA/OH - 2003/008. Ohio Department of Transportation, June 2003.

39. Pant P.D. and Kashayi, Nagaraju. Draft Final Report Crash Base Rates For Intersections In Ohio. Research performed for the Ohio Department of Transportation by University of Cincinnati, Ohio. December 2006

40. Pant P.D. and Panta, Subarna. Draft Final Report Crash Base Rates For Freeways In Ohio. Research performed for the Ohio Department of Transportation by PDP Associates Inc., Ohio. March 2007.\

41. Accident Modification Factors for Traffic Engineering and ITS Improvements, NCHRP report 617, National Cooperative Highway Research Program, 2008. http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_617.pdf, Accessed Dec. 28, 2008.

42. Joan Shen and Albert Gan. Development of Crash Reduction Factors: Methods, Problems, and Research Needs. Transportation Research Board 2003 Annual Meeting CD ROM, Washington D.C., Jan 12-16, 2003.

43. F.M Council, D.W. Reinfurt, B.J. Campbell, F.L.Roediger, L.Carroll, A.K.Dutta, & J.R.Dunham. Accident Research Manual, Publication FHWA/RD-80/016, Federal Highway Administration, US Department of Transportation, 1980

44. Expert System for Highway Safety Analysis Advising. Prepared by University of Cincinnati for Ohio Department of Transportation, February 12, 1996.

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http://www.dot.state.oh.us/research/2005/Safety/14801-FR.pdf. Accessed Nov.28

Appendix I

Simple Before and After Comparison

63


64

Table 1.1: Simple Before and After Comparison for Countermeasures employed in

Intersections from year 2001 – 2004. Intersection

2001

Dist NLF_ID Begin

Log End Log

Countermeasure Before After Percent

3 SHURSR00061**C 2.6 2.7 Channelization and/or Turning Lanes

2 3 -50.00

4 SPORSR00014**C 9.75 11.8 At SR44/Chestnut intersection, upgraded signal to box span; striped SR44/Chestnut with LT storage and added LT phases on all approaches. Completed FA 12/19/01

26 54 -107.69

4 SSUMSR00241**C 4.55 4.65 Channelization and/or Turning Lanes

2 9 -350.00

7 SCLASR00041**C 31 31.1 New Traffic Signal/Flashers 0 1 -100.00 8 SCLEUS00050**C 1.54 1.64 Lanes Added to Traveled Way 8 22 -175.00

2002 Dist NLF_ID Begin

Log End Log


12 SCUYIR00090**C 3.56 3.82 Add lanes completed-monitor results

18 3 83.33

12 SCUYIR00090**C 16.2 18.2 Mill to improve skid resistance duplicate location see above

402 175 56.47

4 SSUMIR00077**C 0 3.8 Epoxy pavement markings, completed 10/15/02; PID #24177

65 25 61.54

4 SSUMIR00077**C 20 21.5 Improve Exit Ramp at Cleve-Mass

60 17 71.67

2003

Dist NLF_ID Begin

Log End Log


12 SLAKSR00091**C 2 4 Left turn phase added 107 172 -60.75 10 SATHUS00033**C 2.77 4.81 Rehabilitate Roadway 112 161 -43.75 4 SMAHSR00007**C 3.45 3.45 Reconstruct intersection,

installing LT lanes on SR164 and SB RT lane on SR 7 and increasing approach radii; Signal upgrade addition of turn phases.

3 5 -66.67

65

12 SLAKSR00306**C 5.55 6.91 New interchange at SR 615 and-90 will help by reducing traffic on SR 306 - monitor

229 300 -31.00

4 STRUSR00007**C 8.6 8.6 At SR82 intersection, construct offset LT lanes on SR82, LT lanes on SR7 and RT lane on SR7 SB approach.

2 5 -150.00

7 SMIASR00055**C 9.79 11.8 HS - City of Troy Widening and Increasing Intersection Radius between SLM 10.50 and 11.15; Replacing 2 Traffic Signals; work to be Completed Spring ‘03, monitor crash frequency.

106 138 -30.19

7 SMIAUS00036**C 10.8 11.1 LS - Removal of parking on street

21 27 -28.57

2004

Dist NLF_ID Begin

Log End Log


3 SMEDSR00018**C 18 20 This section is in a rural area with a high number of Animal accidents. Upgrade signing to meet conditions.

26 36 -38.46

4 SMAHSR00007**C 8 12.1 Improve sign location and size through section after evaluation

139 112 19.42

7 SMOTSR00725**C 14.3 16.3 2003 - Micro surface to improve skid resistance

273 280 -2.56

8 SWARSR00048**C 23.1 23.1 Widn4AprForLTLS/UpgrdSgns 1 0 100.00

12 SLAKSR00306**C 5.18 5.53 New interchange at I-90 and SR 615 should alleviate congestion along the SR 306 corridor

35 30 14.29

66


Interstate from year 2001 – 2004.

Interstate

2001

Dist NLF_ID Begin

Log End Log


4 SSUMIR00076**C 5.9 6.59 Upgrade extrusheet signs, supports, lighting; PID #17965

32 34 -6.25

7 SCLAIR00070**C 2.47 3.97 Remove concrete curb/ fixed deficient radius ramp E

10 14 -40.00

12 SCUYIR00071**C 5.37 5.85 Straighten loop ramps. Remove right turn slip ramps and T the exit ramp into US 42. This work was completed on the southbound exit ramp as part of CUY-71-0.00 project.

104 82 21.15

2002

Dist NLF_ID Begin

Log End Log


12 SCUYIR00090**C 3.56 3.82 Add lanes completed-monitor results

18 3 600.00

12 SCUYIR00090**C 16.2 18.2 Mill to improve skid resistance duplicate location see above

402 175 229.71

4 SSUMIR00077**C 0 3.8 Epoxy pavement markings, completed 10/15/02; PID #24177

65 25 260.00

4 SSUMIR00077**C 20 21.5 Improve Exit Ramp at Cleve-Mass

60 17 352.94

2003

Dist NLF_ID Begin

Log End Log

Countermeasure before after percent

1 SHANIR00075**C 15.1 15.6 Enhance warning signs for SB exit loop ramp

5 17 -240.00

3 SLORIR00090**C 15.3 15.9 Interchange improvements

186 34 81.72

67

4 SSTAIR00077**C 14 18 Include Portable Message Board in construction plans to alert traffic to slower moving traffic ahead

265 436 -64.53

4 STRUIR00080**C 1.57 3.14 Install YIELD sign for WB ramp from US 422

20 16 20.00

6 SFRAIR00070**C 16 18 Install 2 merge warning signs, relocate 3, install 1 Yield sign (LS)

158 267 -68.99

6 SFRAIR00270**C 28 30 Install Watch For Stopped Traffic signs EB 270, east of SR 3 (LS) EVAL

107 130 -21.50

6 SFRAIR00670**C 3 5 Section currently under total reconstruction (HS)

133 342 -157.14

7 SCLAIR00070**C 5.51 6.07 HS - Add Lane Project PID 17448, From 5.14 to 6.83

8 5 37.50

7 SMIAIR00075**C 5.08 5.52 HS - Design Build Project PID 11160, SLM 4.94 to SLM 10.84 Add Lane, Roadway work substantially complete, Open to Traffic.

4 2 50.00

7 SMIAIR00075**C 6 8 HS - Add Lane project to increase interstate capacity.

89 31 65.17

7 SMIAIR00075**C 7.33 9.35 Design build project to add lane on I75, SLM 4.94 to SLM 10.84.

91 31 65.93

11 SBELIR00070**C 20 20 Revise Traffic Signal 14 13 7.14 12 SCUYIR00090**C 12 14 Milled to improve skid

resistance 170 211 -24.12

12 SCUYIR00090**C 18 20 Improve signing and pavement markings

110 208 -89.09

12 SLAKIR00090**C 6.6 7.67 Capacity addition completed in 9/15/03 (4 to 6 lanes) west of SR 306

42 36 14.29

2004

Dist NLF_ID Begin

Log End Log


2 SLUCIR00280**C 4.91 5.1 widen to six lanes 2 0 100.00 4 SSUMIR00076**C 10 12 Extend channel line for I-

76 EB to I-77 SB ramp 168 173 -2.98

7 SMOTIR00075**C 3.74 20.4 2003 Added Thru-75-Arrow

824 737 10.56

7 SMOTIR00075**C 10 12 03 - Micro-surface to correct skid numbers.

72 81 -12.50

68

8 SBUTIR00075**C 0 6.72 Major widening PID 10751 and study PID 75971 should address issues

453 352 22.30

8 SHAMIR00071**C 7.53 8.03 abb, Add signs on Ramps and exit panels

21 23 -9.52

8 SHAMIR00071**C 9.82 10.1 Add speed limit signs 15 12 20.00 8 SHAMIR00071**C 12 14 Rumble strips on

shoulders. 93 119 -27.96


186 183 1.61


180 97 46.11

8 SHAMIR00071**C 18 19.9 Rumble strips on shoulders.

187 141 24.60

8 SHAMIR00074**C 5.73 6.26 Signs/Turnarounds, Signs up 7/13/99

2 2 0.00


2 3 -50.00

8 SHAMIR00074**C 16 18 Rumble strips on new pavement

56 73 -30.36

8 SHAMIR00074**C 17.4 17.7 PID 78082 ramp meters should address issues

10 10 0.00

8 SHAMIR00074**C 18 18.8 PID 78082 to add ramp meters should address issues

34 33 2.94

8 SHAMIR00074**C 18.5 19 continue with projects to redesign interchange and install ramp metering

52 44 15.38

8 SHAMIR00074**C 19.2 19.5 PID 76257 to reconstruct interchange and PID 78082 to install ramp meters should address issues

18 10 44.44

8 SHAMIR00275**C 18.6 20.6 Remove unpaved crossovers.

63 86 -36.51


499 375 24.85

8 SHAMIR00275**C 24 24.6 widening project PID 22386 should address safety issues

60 69 -15.00

8 SHAMIR00275**C 30.7 31.6 PID 20128 to add aux lane from 42 to RHH should address issues

54 29 46.30

8 SWARIR00075**C 10 12.2 PID 10754 widening to the MOT Co line should address issues

22 20 9.09

12 SCUYIR00090**C 14.5 14.9 Install rumble strips 36 34 5.56

69


70


Non-Interstate from year 2001 – 2004.

Non-Interstate

1999

Dist NLF_ID Begin

Log End Log


4 SPORSR00059**C 5.81 7.81 Widen to 4 lanes from Menough to Ravenna West Corp Limit

111 83 25.23

2000

Dist NLF_ID Begin

Log End Log


1 SHANSR00037**C 2.7 3.23 New Traffic Signal/Flashers

12 6 50.00

4 SATBUS00020**C 13.5 14.5 Widen to four std width lanes with necessary left turn lanes where needed from State Rd to SR 11

77 94 -22.08

4 SMAHSR00046**C 13.9 14.7 Traffic Signs, Pavement Markings and/or Delineators

98 94 4.08

4 SPORSR00303**C 6.83 8.02 Minor Structures Replaced or Improved for Safety

7 5 28.57

7 SMOTSR00741**C 4.28 7.37 Lanes Added to Traveled Way

200 124 38.00

8 SBUTSR00747**C 1.71 3.16 Lanes Added to Traveled Way

17 105 -517.65

8 SCLESR00125**C 7.02 8.63 Channelization and/or Turning Lanes

77 49 36.36

8 SCLESR00125**C 7.02 8.63 Channelization and/or Turning Lanes

13 7 46.15

8 SCLEUS00052**C 5.32 6.1 Roadway Realignment 183 141 22.95 9 SLAWSR00007**C 5.04 5.14 Traffic Signs 15 9 40.00

2001

Dist NLF_ID Begin

Log End Log


1 SDEFSR00066**C 0.97 2.06 Sight Distance Improvements

1 1 0.00

71

4 SATBSR00045**C 19.3 19.9 ATB-45-19.74, PID #18703, Completed Aug.01: Added SR45 center turn lane storage and LT storage on I-90 exit ramps

14 24 -71.43

4 SATBUS00020**C 12.8 13.3 ATB-20-20.921(M), PID #8254, Completed July 01: Widen viaduct to four std width lanes with necessary left turn lanes where needed from Park Ave to State Rd.

29 51 -75.86

4 SMAHSR00046**C 14.7 14.7 Extended SR46 turn lane storage lengths; Signal upgrade; MAH-46-14.52, PID #14974 Project completed 5-31-01

27 33 -22.22

4 SMAHSR00046**C 14.7 14.9 Channelization and/or Turning Lanes

15 6 60.00

4 SPORSR00014**C 9.01 10.3 S.R.44/Chestnut re-striped to add LT lanes on existg pavt. Signal upgraded to box span and LT phases added.

22 22 0.00

4 SPORSR00043**C 8 10 Resurfaced SLM 8.30-15.51, PID 17880

105 102 2.86

4 SPORSR00043**C 13.5 14 Guardrail end treatments upgraded with project POR-43-8.300, #17880

10 4 60.00

4 SSTASR00687**C 2.46 2.46 STA-687-1.94, PID #6256 Completed 10/31/01. Widened SR-687 through intersection. Everhard widened by county 1998, STA-CR98-2.29, PID #4276.

12 16 -33.33

4 SSUMSR00241**C 4.09 4.49 S.R. 241 @ S.R. 619 intersection widened for turn lanes, added intersection lightg and sig. upgrade

12 26 -116.67

4 STRUSR00087**C 0 2.51 Lanes Added to Traveled Way

17 5 70.59

5 SFAISR00037**C 11.4 11.5 Channelization and/or Turning Lanes

6 5 16.67

5 SFAISR00188**C 4.46 4.56 Sight Distance Improvements

1 5 -400.00

72

5 SKNOUS00036**C 18.2 19.1 Make Division St. lef a one-way which would eliminate the left turn from US 36. District will meet with the city to discuss this suggestion.

16 79 -393.75

5 SLICSR00161**C 2.14 2.24 Channelization and/or Turning Lanes

13 16 -23.08

7 SMOTSR00202**C 5.17 5.27 Lanes Added to Traveled Way

8 11 -37.50

8 SCLEUS00050**C 4.72 5.84 Widen to 12ft lane and 4ft shoulders

27 12 55.56

8 SCLEUS00050**C 7.66 8.26 Repaved 2 1 50.00 8 SHAMSR00264**C 6.85 6.95 Channelization and/or

Turning Lanes 15 33 -120.00

10 SNOBSR00078**C 5.49 6.89 Widened Traveled Way (No Lanes Added)

1 1 0.00

11 STUSUS00250**C 19.2 21.7 2. a. A construction project at the intersection of McCauley Drive was completed in October 2001. The project added turn lanes, new concrete pavement, new signals, new signal ahead signs w/flashers, and new pavement markings.

55 35 36.36

12 SLAKSR00608**C 0.3 0.96 Hill repaved for skid resistance

3 0 100.00

12 SLAKSR00608**C 0.5 1 Hill repaved for skid resistance

3 0 100.00

2002

Dist NLF_ID Begin

Log End Log


4 SATBSR00534**C 19.3 20.4 MAJOR REHABILITATION OF BRIDGE OVER IR 90.

21 6 71.43

11 SCOLSR00045**C 15.1 15.8 ADD A 2WLTL, INCLUDING A CURBED TYPICAL SECTION WITH A CLOSED DRAINAGE SY STEM. CONSTRUCT SIGNALIZED INTERSECTION.

16 5 68.75

12 SCUYUS00422**C 15.2 17.2 Added Turn Lanes on Harper Road Exit Ramp in 2002 to relieve queuing onto Freeway -

91 28 69.23

73

monitor -skid test pavement

3 SERIUS00250**C 9.75 10.4 Widen to 5-lanes 9 0 100.00 9 SJACSR00093**C 7 9 Install large Arrow sign

with flashers, Overlay pavement

2 0 100.00

9 SJACSR00093**C 14.9 15.4 Monitor, Pavement was widened in June 2002 to provide a center two way left turn lane

25 6 76.00

9 SJACSR00093**C 15 15.4 WIDEN A SECTION OF SR93 AND ADD A CEN TER TWO-WAY LEFT-TURN LANE FOR SAFETY.

22 6 72.73

9 SJACSR00093**C 15 15.4 Widen pavement for two way left turn lane

22 6 72.73

12 SLAKSR00640**C 1.76 2.14 Widening project completed

25 4 84.00

2 SLUCUS00020**C 18.9 19.2 build new four lane bridge

21 2 90.48

4 SMAHSR00045**C 11.8 11.8 Warning sign relocation on county route approaches and signal timing/phasing operational evaluation.

4 1 75.00

7 SMOTUS00040**C 3.13 3.13 Upgraded Stop Signs and added Stop Lines.

1 0 100.00

4 SSUMSR00018**C 2.12 2.58 Recent projects added cap. via addtl lanes & signal cood. (PID #7861 & #20697). Requires correction of I value = 6, slm 2.10-3.16 and recalc. HSP rank. Refer to SCWP.

72 27 62.50

4 SSUMSR00018**C 8 10 Widen to standard lane width with turn lanes where needed; drainage, curbs, sidewalks, lighting; access management, signal upgrade/coordination, drainage improvements; create off street parking

108 43 60.19

4 SSUMSR00091**C 17.2 18.2 S.R. 91 widened to 5 lanes north of Old Mill, installed signal at Old Mill

25 10 60.00

74

4 SSUMSR00093**C 6.92 7.71 Resurfaced 9/30/02; PID#17949 (included striping change NB at Cormany)

28 23 17.86

10 SVINUS00050**C 11.4 13.6 Widen US 50 and perform minor horizontal and vertical realignments.

3 1 66.67

10 SVINUS00050**C 11.9 14 ROAD REALIGNMENT, WIDENING AND PAVING SHOULDERS, DRAINAGE, GRADING, AND RESURFACING WITH GUARDRAIL INSTALLATION

3 0 100.00

8 SWARSR00123**C 16.5 16.9 sign improvements 1 0 100.00

2 SWOOSR00065**C 5.91 6.62 REALIGN TO PROVIDE PROPER SUPERELEVATION BY CHANGING HORIZ. & VERTICAL CURVES; RELOCATE TR-22 & SR-65 INTERSECTION FOR PROPER SIGHT DISTANCE; PERFORM RELATED WORK.

3 0 100.00

2003

Dist NLF_ID Begin

Log End Log

Countermeasure before after percent

8 SCLESR00125**C 0 2 Remove School Crossing sign in front of Thomas More

387 669 -72.87

12 SCUYSR00091**C 0 2.45 TRAC funded widening project completed

99 66 33.33

2 SWOOUS00020**C 0 0.46 build new four lane bridge

10 15 -50.00

4 STRUSR00193**C 0.2 1.48 Install Closed Loop System

49 74 -51.02

4 SSTASR00172**C 0.9 0.9 Install O.H. flasher at Alabama Ave intersection. Sign upgrade & visibility improvements via foliage removal. Create left turn lane on SR 172 on existing pavement - no widnening

3 0 100.00

4 STRUSR00046**C 1.7 2.6 Resurface with skid resistant material - PID 19850 FY 2003

6 4 33.33

75

8 SHAMSR00125**C 1.76 2.5 City creating 5 lane section, under construction.

73 79 -8.22

8 SCLESR00126**C 1.78 1.78 Trim Trees, add signs 2 0 100.00 10 SWASSR00060**C 1.82 2.83 Permit Review to

Ensure Compliance 42 71 -69.05

8 SCLESR00125**C 2 4 McMann-Gordon intersection improved 2002

100 143 -43.00

12 SLAKSR00002**C 2 4 IR90 and SR615 new interchange construction to be completed fall FY2003 will help SR 2 corridor

83 127 -53.01

7 SMIASR00202**C 2.03 2.03 Re-alignment/ Traffic Signal

6 5 16.67

10 SATHUS00033**C 3.29 3.88 Rehabilitate Roadway, including Access Management

33 50 -51.52

8 SCLESR00125**C 3.31 3.31 (CONT: CLOSE DRIVES/RELOCATE DR

2 1 50.00

8 SCLESR00125**C 3.44 3.44 TurnLns/ReloMcMan&Gordon/UpgrdSgnl

9 10 -11.11

4 STRUSR00046**C 3.72 5.52 Upgrade and interconnnect signals via PID 22204, FY03

90 70 22.22

12 SCUYSR00017**C 3.76 4.39 Realignment at Grayton Road completed - monitor results

2 20 -900.00

12 SCUYUS00020**C 3.99 3.99 New signal installed November of 2003/recommend monitoring and waiting for 2004 and 2005 accident data to reevaluate effectiveness of improvements

3 5 -66.67


142 153 -7.75

12 SLAKSR00306**C 4 4.74 New interchange at SR 615 and-90 will help by reducing traffic on SR 306 - monitor

17 30 -76.47

7 SMOTSR00048**C 4 6 MM - Close (or Right-In/Right-Out) Access Points,Access Management

123 151 -22.76

4 SATBUS00020**C 4.66 4.66 ATB-20-4.67, PID #24093, FY03 CO: Install 4-phase, fully-actuated signal at

3 1 66.67

76

Meyers Road intersection

3 SMEDSR00303**C 4.98 4.98 Signing improvements 3 4 -33.33

11 STUSSR00800**C 5.17 5.79 Add curve signing 1 1 0.00 8 SHAMSR00125**C 5.39 7.39 County improving

Asbury, add lanes on Asbury, drive improvements on 125

182 474 -160.44


86 110 -27.91

12 SGEASR00088**C 6.11 6.11 Signalization 0 2 #DIV/0!


186 252 -35.48

4 STRUSR00005**C 6.6 7.19 Skid resistant paving of W. Market interchange

3 1 66.67

8 SBUTSR00747**C 7.03 7.03 CutHill,Radii,LTLs 6 6 0.00 12 SLAKSR00306**C 7.08 7.84 New interchange at SR

615 and-90 will help by reducing traffic on SR 306 - monitor

53 62 -16.98

5 SFAIUS00033**C 8 10 Coonpath Rd. signal is being rebuilt and upgraded as part of the bypass construction. Left turn lanes are being constructed on all approaches.

0 6 #DIV/0!

8 SHAMSR00264**C 8 10 Adding protected lt. phase at Westbourne this year.

274 431 -57.30

7 SMOTSR00202**C 8.57 8.87 LS - Restrict turning movements, Review Signal Timing and Coordination.

56 68 -21.43

8 SHAMSR00264**C 8.64 8.64 Improved signal coordination,Westbourne/Law.

15 12 20.00

7 SMIAUS00036**C 8.83 10.1 HS - City has widened roadway and installed a new traffic signal at US 36 and College St.

31 50 -61.29

3 SLORSR00082**C 9.05 9.05 Upgrade crossroad warning signs

10 1 90.00

77

7 SMOTSR00202**C 9.1 9.62 LS - Restrict turning movements, Review access management.

12 14 -16.67

9 SSCIUS00023**C 9.36 11.4 Install Watch For Stopped Traffic signs and Thru Traffic Keep Right signs / Request Increased enforcement of speed limit,

42 38 9.52

4 STRUSR00045**C 9.41 11.4 Signal head blocking NB O.H. advance signing for 5/82 WB Entr ramp. Improve location of sign - advance ground mount

71 80 -12.68

5 SLICSR00013**C 9.88 10.1 City of Newark completed signal upgrades Jan 03. ODOT will work with the city to monitor, optimize, and coordinate signal timing.

39 33 15.38

5 SFAIUS00033**C 10 12 As a low cost, short term countermeasure, ODOT will better interconnect the signals at Collins Rd. and Victor Dr.

1 4 -300.00

4 SSUMSR00261**C 11.6 12 Adjust signal timing - letter to city

76 67 11.84

12 SCUYSR00087**C 11.8 13.8 Restripe narrow 4 lanes to 3 lanes with center two way left turn lane

89 131 -47.19

8 SHAMUS00022**C 12.5 12.5 Remove signs / vegetation

32 35 -9.38

4 SMAHSR00046**C 12.8 14.8 Perform semi-annual striping

122 122 0.00

:LO) SCUYSR00014**C 13.1 13.1 New signal installed May of 2003/recommend monitoring and waiting for 2004 and 2005 accident data to reevaluate effectiveness of improvements

1 12 -1100.00

9 SROSSR00104**C 14.2 14.4 Widen off ramp to add right turn lane, move signal pole for widening

21 19 9.52

4 SSUMSR00008**C 16 18 Install advance street name signs

171 320 -87.13

8 SHAMUS00022**C 18 19.3 Developer adding TWLTL between Union Cemetery and Enyart.

100 173 -73.00

78

9 SROSUS00035**C 20.1 20.5 Revise signal timing, Install Through Traffic Keep Left signs

8 2 75.00

8 SCLIUS00068**C 20.4 20.8 Work to be done by developer, add turn lanes at intersection

6 8 -33.33

10 SWASSR00007**C 21.5 21.9 Coordinate and Optimize Signals

25 20 20.00

10 SWASSR00007**C 22.8 22.8 Optimize Signal Timing 13 20 -53.85

4 SSTAUS00062**C 24 28 Install / replace RPMs 283 470 -66.08

2004 Dist NLF_ID Begin

Log End Log


1 SALLSR00309**C 10.9 10.9 Modify signal clearance (y & all red) times.

4 9 -125.00

2 SLUCSR00025**C 8.2 8.47 review time-lapse video to identify current traffic patterns

19 20 -5.26

3 SERIUS00006**C 0.88 1.41 Install flashers on night arrow sign

3 1 66.67

3 SLORSR00002**C 7.97 9.97 Install edgeline rumble strips from slm 3.48 to 8.0 (Rumble strips already installed from slm 8.0 to slm 11.14 (I-90).)

23 12 47.83

3 SLORSR00057**C 18.2 20.2 Optimize traffic signal operation at SR 57 and IR 90.

234 209 10.68

3 SLORSR00057**C 20.2 22.2 Optimize traffic signal operation at SR 57 and SR 254.

90 95 -5.56

3 SMEDSR00018**C 18 20 This section is in a rural area with a high number of Animal accidents. Upgrade signing to meet conditions.

26 36 -38.46

3 SMEDSR00083**C 0.01 0.51 Replace existing signal ahead signs with flourescent yellow signal ahead signs.

9 3 66.67

3 SMEDUS00042**C 18 20 Improve pavement markings and lane use signing.

97 58 40.21

3 SMEDUS00042**C 20.8 21.3 Install 45mph speed zone from end of exist. 35mph speed zone to Sleepy Hollow Road.

10 5 50.00

79

3 SRICUS00042**C 12 14 Evaluate signing and pavement markings for improvements. Implement any indicated changes.

72 53 26.39

3 SRICUS00042**C 14 16 Evaluate speed limits for possible adjustments.

40 33 17.50

4 SMAHSR00007**C 8 12.1 Improve sign location and size through section after evaluation

139 112 19.42

4 SMAHSR00626**C 0.4 0.9 Improve lane and shoulder width and degree of curvature and/or superelevation of the curve between slm 0.40 and slm 0.70.

2 0 100.00

4 SMAHUS00224**C 17.9 19.1 Skid Resistant Overlay, slm 18.22 - 20.72

234 179 23.50

4 SPORSR00261**C 3.85 3.85 _Add protected_permissive left turn phases to signal operation. WB and SB left turns heaviest

4 7 -75.00

4 SSTASR00173**C 1.85 1.85 Intersection realignment/relocation to create standard 2-way stop condition on the Columbus (CR67) approaches

2 0 100.00

4 SSUMSR00091**C 9.59 9.59 Add second 5-unit signal head for EB left turn

18 13 27.78

4 STRUSR00046**C 10.5 10.5 Realign intersection of McCleary-Jacoby with SR 46, Add NB LT lane on SR 46

1 0 100.00

4 STRUSR00082**C 16.8 18.8 Restripe EB ramp from E. Market to one lane to reduce number of lanes merging onto SR 82 - Not Performed: See Comments

121 39 67.77

4 STRUUS00422**C 9.92 11.4 Upgrade and interconnect signals along section. Included in citywide closed loop project. PID 22694 FY03

33 23 30.30

6 SFRASR00317**C 5.18 5.18 add left and right turn lanes at Rohr Road intersection

1 1 0.00

6 SFRAUS00033**C 26 28 remove traffic signal (LS) EBRIGHT

42 22 47.62

7 SMIASR00041**C 9.49 9.49 LS - Re Design Traffic 3 2 33.33

80

Pattern 7 SMOTSR00201**C 7.37 9.37 2003 Major Rehab on

SR 201 N of I70 57 113 -98.25

7 SMOTSR00725**C 12.3 14.3 2003 - Micro-surfaced to improve skid numbers

81 41 49.38

7 SMOTSR00725**C 14.3 16.3 2003 - Micro surface to improve skid resistance

273 280 -2.56

7 SMOTSR00741**C 2.93 2.93 LS-Review and improve pavement markings, repair twisted sign, add LT Lane sign.

18 18 0.00

7 SSHESR00047**C 14 15.5 2003 Roadway improvements to SR 47 and 4th Ave

85 65 23.53

8 SBUTSR00004**C 0.44 4.89 PID 76380 to add nb and sb lanes should address issues

366 319 12.84

8 SBUTSR00004**C 12 14 Upgrade Stop when flashing sign at SR747.

37 48 -29.73

8 SBUTSR00004**C 23.3 24.3 ADD 2 ThruLNS TRENTN/FRNKLN-BRDG

10 8 20.00

8 SBUTSR00747**C 0 2 Left turn on arrow only, if left turns are a problem at Mulhauser

83 68 18.07

8 SBUTSR00747**C 1.01 1.01 continue with countermeasure to install protected left

10 5 50.00

8 SCLESR00028**C 6.83 8.83 Adding left turn lane at Goshen with resurfacing

34 27 20.59

8 SCLESR00032**C 0 2 Remove median crossing at Roney Lane, eliminate lefts

115 56 51.30

8 SCLESR00032**C 8 10 Fix prepare to stop when flashing, use correct size symbolic sign.

57 70 -22.81

8 SCLESR00125**C 6 8 Left turn lanes at newly relocated Cecilia in Amelia, by village

78 75 3.85

8 SCLESR00131**C 2 4 Improve alignment 72 46 36.11 8 SGREUS00035**C 2.55 4.55 Interchange being

constructed at North Fairfield Road

117 61 47.86

8 SHAMSR00125**C 3.39 5.39 Change Salem from Protected left to protected/permissive

57 70 -22.81

8 SHAMSR00562**C 0.56 1.06 The placement of the flasher west of this section should address safety issues

24 18 25.00

8 SHAMUS00027**C 11.4 14.3 PID 76378 to add median should address

387 414 -6.98

81

issues

8 SHAMUS00027**C 11.7 13.7 Under construction for center median.

271 289 -6.64

8 SHAMUS00027**C 13.1 14.4 Access Management / Raised Median

180 202 -12.22

8 SHAMUS00027**C 14.3 14.3 Access Management / Raised Median

1 1 0.00

8 SHAMUS00027**C 14.7 14.7 Add right turn lane NB 16 10 37.50

8 SHAMUS00127**C 11.9 13.9 Spingdale intesection 12.75 on HSP being studied, add LT. phase.

32 60 -87.50

8 SHAMUS00127**C 12.8 12.8 Retime signal 5 11 -120.00

8 SWARSR00048**C 23.1 23.1 Widn4AprForLTLS/UpgrdSgns

1 0 100.00

8 SWARSR00122**C 2.77 3.42 Widen to 12ft lane and 8shoulders

10 6 40.00

8 SWARSR00132**C 2.58 2.58 Improve sight dist., cut hill to south

1 0 100.00

8 SWARUS00022**C 5.37 5.37 RECNST INTRSCT/SIGNL TO 8 PHS/LTLS

7 12 -71.43

9 SBROSR00032**C 11.1 11.1 Install stop & go signal 0 1 -100.00

9 SJACSR00093**C 14 16 Resurface pavement, Install new RPMs and thermoplastic pavement markings/14.40-15.33 scheduled for widening Nov. 2008 (See HSP locations)

68 56 17.65

9 SLAWSR00093**C 3.88 4.66 The DSRT recommends to remove unwarranted guardrail posts and monitor accidents, The speed limit was reduced to 45 mph in 2002

7 12 -71.43

10 SWASUS00050**C 9.73 10.5 Improve Signing and Striping

9 8 11.11

12 SLAKSR00044**C 0 2.07 Perform skid test and modify pavement as necessary. Emergency contract sold (project 9075-04) and work completed.

57 51 10.53

82

12 SLAKSR00044**C 1.69 2.3 Perform skid tests on ramps and improve skid resistance of pavement where needed. Emergency contract sold (project 9075-04) and work completed.

58 57 1.72


35 30 14.29

83

This page is intentionally left blank ]

84

Appendix II

AID Tree Diagram for Rear – End Crashes

85


86

The keys to read the following figures are:

SPEEDLIMIT = Speed Limit in miles (1 mile = 1.6 km) ADTTOTAL= Average Daily Traffic POPDEN = Population Density (within a radius of 1.99 miles (3.2 km) of the begin log county) LANES = No. of Lanes ROADWAYWIDT = Roadway Width in ft. (1 ft. = .0348 m) SURFACE_WIDT = Surface Width in ft. (1 ft. = .0348 m) SLIW = Shoulder Left Inside Width in ft. (1 ft. = .0348 m) SRIW = Shoulder Right Inside Width in ft. (1 ft. = .0348 m) MEDIANWIDTH = Median Width in ft. (1 ft. = .0348 m) VC_RATIO = V/C Ratio DIST_TO_INTC = Distance to Interchange in miles (1 mile = 1.6 km) DINJFAT = Injury/ Fatal crash density DPDO =Property damage only crash density DTOTAL =Total crash density DANGLE = Angle crash density DFIXEDOBJ = Fixed object crash density DREAREND = Rear end crash density DSIDESWIPE = Sideswipe crash density DROADWET =Road wet crash density DNIGHT = Night crash density RINJFAT = Injury/ Fatal crash rate RPDO =Property damage only crash rate RTOTAL =Total crash rate RANGLE = Angle crash rate RFIXEDOBJ = Fixed object crash rate RREAREND = Rear end crash rate RSIDESWIPE = Sideswipe crash rate RROADWET =Road wet crash rate RNIGHT = Night crash rate

87


88

Figure1. AID Tree diagram for rear end accident density for all 12 districts of rural highways without intersection.

89

Figure2. AID Tree diagram for intersections With One Way Stop Sign - No Control Legs - Rear end Crashes

REAREND

Mean=0.070SD=0.199

N=489

Mean=0.026SD=0.112

N=287

ADT<3760.000

Mean=0.134SD=0.267

N=202

Mean=0.099SD=0.219

N=128

LEFT_THR<1.000

Mean=0.194SD=0.326

N=74

Mean=0.144SD=0.282

N=44

ADT<7120.000

Mean=0.267SD=0.375

N=30

90

Figure 3. AID Tree diagram for T Intersections with One Way Stop Sign - Stop Control Legs - Rear end Crashes

REAREND

Mean=0.031SD=0.198

N=240

Mean=0.010SD=0.065

N=210

ADT<3190.000

Mean=0.178SD=0.516

N=30

Figure 4. AID Tree diagram for Two Way Stop Control Intersections- No Control Legs - Rear end Crashes

REAREND

Mean=0.066SD=0.277

N=313

Mean=0.046SD=0.125

N=283

ADT<7210.000

Mean=0.256SD=0.796

N=30

Mean=0.032SD=0.103

N=231

ADT<4770.000

Mean=0.109SD=0.183

N=52

91

Figure 5. AID Tree diagram for Two Way Stop Control Intersections- Stop Control Legs - Rear end Crashes

REAREND

Mean=0.044SD=0.179

N=313

Mean=0.027SD=0.104

N=280

ADT<2420.000

Mean=0.182SD=0.442

N=33

Figure 6. AID Tree diagram for Flashing Beacon Control Intersections- No Control Legs - Rear end Crashes

REAREND

Mean=0.092SD=0.256

N=119

Mean=0.040SD=0.121

N=83

ADT<5840.000

Mean=0.213SD=0.407

N=36

92

Figure 7. is for AID Tree diagram For Flashing Beacon Control Intersections- Stop Control Legs - Rear end Crashes

REAREND

Mean=0.081SD=0.176

N=152

Mean=0.042SD=0.120

N=110

ADT<3140.000

Mean=0.183SD=0.246

N=42

Mean=0.022SD=0.083

N=61

ADT<2030.000

Mean=0.068SD=0.152

N=49

93

Figure 8. AID Tree diagram for Signalized Intersection Legs - Rear end Crashes

REARENDMean=0.432SD=0.922

N=835

Mean=0.252SD=0.514

N=688

ADT<14690.000

Mean=1.272SD=1.659

N=147

Mean=0.943SD=1.209

N=106

ADT<23620.000

Mean=2.122SD=2.276

N=41

Mean=0.151SD=0.311

N=482

ADT<8140.000

Mean=0.487SD=0.761

N=206

Mean=0.645SD=1.036

N=46

Mean=1.172SD=1.288

N=60

ADT<18270.000

94

Figure 9.AID Tree diagram for rear end accident density for statewide freeways.

DREARENDMean=22.499

SD=63.320N=3813

Mean=8.505SD=24.343

N=2824

ADTTOTAL<77220.000

Mean=62.456SD=107.789

N=989

Mean=50.377SD=83.608

N=888

Mean=168.657SD=200.250

N=101

DIST_TO_INTC<0.030

Mean=38.306SD=60.408

N=752

ADTTOTAL<142120.000

Mean=117.121SD=142.581

N=136

Mean=28.821SD=33.384

N=43

Mean=157.948SD=154.898

N=93

DIST_TO_INTC<0.550

95

Figure 10. AID Tree diagram for rear end accident rate for statewide freeways.

RREAREND

Mean=1.972SD=5.928N=3813

Mean=0.987SD=2.994N=2995

POPDEN<828.656

Mean=5.575SD=10.704

N=818

Mean=4.634SD=9.288

N=739

Mean=14.383SD=17.231

N=79

DIST_TO_INTC<0.020

96