Synthesis of Safety for Traffic Operations - Transports Canada

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Synthesis of Safety for Traffic Operations March 2003 How do you practice EBRS? There are two main concerns that need to be assessed in applying research results to a practical problem facing a practitioner: 1. Has the research been conducted using sound methods such that the results can be considered valid? and 2. Are the results applicable to the particular situation? The traffic operations professional is practicing EBRS if (s)he is following these seven steps when dealing with road safety issues: 1. Identify a problem or area of uncertainty 2. Formulate a relevant, focused question that needs to be answered 3. Find and appraise the evidence 4. Assess the applicability to your situation 5. Decide whether or not to take action 6. Evaluate the outcomes of your actions/inaction 7. Summarize/record the results Through this process EBRS considers the following things in a meaningful way: • Population: What is the population or site-specific conditions (signalized intersections, rural two-lane roads, etc.)? • Problem: What is the problem (crash types, severity)? • Interventions: What are the interventions being considered (including traffic operations and control strategies, geometric design changes, driver education, and “do nothing”)? • Outcomes: Is the intervention effective and do the safety and other impacts concur with operating practice and local policy? EBRS is achievable and a necessary component of informed decision-making on road safety matters. The following is an example of the appropriate use of EBRS in practice. One of the elected officials, on behalf of her constituency, is seeking “back-to-back green arrows” for the left turn movement on the main street at a signalized intersection. The request cites “safety concerns” at this “dangerous location”. The traffic operations (i.e., intersection and approach delay, volume to capacity ratio, etc.) under the present twophase, and the proposed three-phase operation would be satisfactory. Therefore, the Page 187
Evidence-based Road Safety traffic operations staff is faced with deciding whether to recommend the left-turn phasing to improve safety. The seven steps of the EBRS process are used as follows: 1. Identify a problem or area of uncertainty Does the intersection have a crash problem related to left-turns from the main street? Are left-turn-opposing through crashes over-represented? Are the crashes more severe than expected? 2. Formulate a relevant, focused question that needs to be answered What impact does a protected left-turn phase on the main street of a four-leg, urban, signalized intersection have on safety? (NOTE: Forming the question includes defining the treatment(s) being considered, and the site characteristics). 3. Find and appraise the evidence Using conventional literature searches, internet searches, material contained in this Synthesis, personal contact with other professionals, and other methods find information on the safety impacts of protected left-turn phasing. After assembling the available material, use the appraisal form in Appendix B to appraise the quality of the research and assess the reliability of the results. 4. Assess the applicability to your situation As much as possible determine if the reliable research identified in Step 3 was conducted on similar conditions to the situation of concern to you now. For instance, the current problem is at an urban, four-leg intersection – was the research conducted on similar intersections? 5. Decide whether or not to take action Will the protected left-turn phasing be effective in addressing the identified problem? If so are there other concerns that may preclude action (i.e., unacceptable environmental damage, violation of local policy, etc.)? Are there other equally effective options that need to be considered? 6. Evaluate the outcomes of your actions/inaction Monitor the location in the short- and long-terms. If a treatment was implemented, then the long-term evaluation of effectiveness will assist in building local CMFs and evidence-based knowledge. 7. Summarize/record the results Document the results of the project. Page 188
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Transport Canada Transports Canada
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Synthesis Of Safety For Traffic Ope
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DISCLAIMER The material presented h
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EXECUTIVE SUMMARY Traffic operation
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Synthesis of Safety for Traffic Ope
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TABLE OF CONTENTS DISCLAIMER REJET
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LIST OF TABLES TABLE 3.1: Crash Rat
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Chapter 1: Chapter 1: Introductio I
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Introduction Before proceeding, a f
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Introduction Literature regarding t
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Introduction The current science of
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Introduction adequate size control
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Introduction In concluding this sec
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Chapter 3: Chapter 3: Intersectio I
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Intersection Control TABLE 3.3: Cra
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Intersection Control TABLE 3.5: CMF
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Intersection Control Vancouver Regi
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Intersection Control V m = the sum
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Intersection Control where: X1 = 0
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Intersection Control Region of Durh
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Intersection Control TABLE 3.17: CM
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Intersection Control The predictor
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Intersection Control program includ
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Intersection Control TABLE 3.26: Me
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Intersection Control TABLE 3.29: St
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Intersection Control TABLE 3.32: Ni
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Intersection Control It is noted th
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Intersection Control Sayed et al (1
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Intersection Control Signal Clearan
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Intersection Control The CMFs are 0
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Intersection Control also examined
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Intersection Control Shebeeb (1995)
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Intersection Control approaches at
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Intersection Control TABLE 3.56: Sa
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Chapter 5: Chapter 5: Pavement Pave
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Pavement Markings The study methodo
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Pavement Markings Hall (1987) Hall
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Pavement Markings TABLE 5.8: Safety
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Pavement Markings THIS PAGE IS INTE
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Chapter 7: Chapter 7: Bicycle Bicyc
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Bicycle Safety TABLE 7.1: Safety Im
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Chapter 9: Chapter 9: Turn Lanes Tu
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Turn Lanes TABLE 9.2: Safety Impact
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Turn Lanes Vogt determined that a l
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Turn Lanes 1998 one of their high c
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Turn Lanes Section TABLE 9.10: Safe
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Turn Lanes A T = ADT 0.91 L 0.852 e
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Turn Lanes CMF = 1 - 0.7 P lt/d 0.0
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Turn Lanes occurred within 250 feet
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TABLE 10.3: Speed Changes Resulting
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Sites Where Applied 1 URBAN Island
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Forbes and Gill (2000) undertook a
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Ideally, three years of before and
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Kermit and Hein (1962) looked into
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The effects of the transverse pavem
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Chapter 11: Chapter 11: Other Other
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Other Safety Issues collisions per
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Other Safety Issues THIS PAGE IS IN
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Page 220: References References
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Page 225 and 226: References Hamilton Associates (199
Page 227 and 228: References Lee JT, Maleck TL, and T
Page 229 and 230: References Polanis SF (1998) “Do
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Page 233 and 234: References THIS PAGE IS INTENTIONAL
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Page 245 and 246: Critical Reviews Worksheet for Eval
Page 247 and 248: Critical Reviews 2. Are the expecte
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