Synthesis of Safety for Traffic Operations - Transports Canada

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Synthesis of Safety for Traffic Operations March 2003 It is curious to note that the right-turn channelization in urban areas is associated with an increase in crashes. Harwood et al (2000) Harwood et al (2000) using an expert panel of road safety professionals reviewed the available evidence on the safety impacts of adding right turn lanes to the main street approaches at the intersections of rural, two-lane highways. The panel opined that CMFs for right-turn lanes are as shown in Table 9.16. TABLE 9.16: CMFs for Right Turn Lanes Number of main street approaches on Traffic which right-turn lanes are added Control One Approach Both Approaches Stop 0.95 0.90 Signal 0.975 0.95 Chin and Quddus (2001) Chin and Quddus (2001) in analysing four-legged signalized intersections in Singapore, Japan found that right turn lanes on both approaches increased crash frequency by 38% (CMF=1.38), and left-turn lanes on both approaches decreases crash frequency by 53% (CMF=0.47) 5 . Harwood et al (2002) In a comprehensive analysis of the safety impacts of left- and right-turn lanes, Harwood et al (2002) conducted before-after studies for intersection improvements in eight states. A total of 280 sites were treated and 300 sites were used as comparison or reference sites. The sites were in urban and rural settings and were either two-way stop controlled, or signalized (i.e., all-way stop controlled sites were excluded from the analysis). All sites had either three or four approaches; all approaches were public streets (i.e., no private driveways were included in the sites). The Harwood et al study employed three different evaluation methods: the matched-pair approach, the before-after evaluation with a comparison group, and the before-after study using Empirical Bayes methods. Crashes that were included in the analysis are those that 5 The rules of the road in Singapore require driving to the left of the centreline. Therefore, in the Chin and Quddus article, right-turns are equivalent to left-turns in Canada and have been adjusted accordingly. Page 121
Turn Lanes occurred within 250 feet of the intersection, and were coded as intersection-related. Before and after time periods varied between one and 10 years, with averages of 6.7 years and 3.9 years, for the before and after periods, respectively. The results of the analysis and the recommendations of the researchers are shown in Table 9.17. TABLE 9.17: Safety Impacts of Right-turn Lanes on Major Road Approaches No. of Approaches on which Traffic Control Left-turn Lanes are added One Two STOP control 0.86 0.74 Signal 0.96 0.92 Page 122
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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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Page 124: Chapter 7: Chapter 7: Bicycle Bicyc
Page 127 and 128: Bicycle Safety TABLE 7.1: Safety Im
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Page 151 and 152: Turn Lanes TABLE 9.2: Safety Impact
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Page 155 and 156: Turn Lanes 1998 one of their high c
Page 157 and 158: Turn Lanes Section TABLE 9.10: Safe
Page 159 and 160: Turn Lanes A T = ADT 0.91 L 0.852 e
Page 161: Turn Lanes CMF = 1 - 0.7 P lt/d 0.0
Page 168 and 169: TABLE 10.3: Speed Changes Resulting
Page 170 and 171: Sites Where Applied 1 URBAN Island
Page 172 and 173: Forbes and Gill (2000) undertook a
Page 174 and 175: Ideally, three years of before and
Page 176 and 177: Kermit and Hein (1962) looked into
Page 178 and 179: The effects of the transverse pavem
Page 180: Chapter 11: Chapter 11: Other Other
Page 183 and 184: Other Safety Issues collisions per
Page 185 and 186: Other Safety Issues THIS PAGE IS IN
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References References
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References Bloch SA (1998) “Compa
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References Hamilton Associates (199
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References Lee JT, Maleck TL, and T
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References Polanis SF (1998) “Do
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References Vancouver, City of (1999
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References THIS PAGE IS INTENTIONAL
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Appendix B: Critical R Appendix B:
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Critical Reviews Worksheet for Eval
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Critical Reviews 2. Are the expecte
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Appendix D: Appendix D: How to Use
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How to Use Safety Performance Funct
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How to Use Safety Performance Funct
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