Synthesis of Safety for Traffic Operations - Transports Canada

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Sites Where Applied 1 URBAN Island Geometry RURAL Description Lane approaching urban area has minor deflection, straight lane departing urban area 2 and 4 URBAN RURAL Lane approaching urban area has a medium deflection, straight lane departing urban area 3 URBAN RURAL Approaching and departing lanes have a medium deflection 5 URBAN RURAL Lane approaching urban area has a large deflection, straight lane departing urban area FIGURE 10.1: Traffic Calming Islands in Austria The study methodology was a naïve before-after analysis of mean, 85 th percentile, and maximum observed speeds recorded near the town sign (which presumably is proximate to the island). The results are shown in Table 10.7. TABLE 10.7: Speed Effects of Gateway Treatments in Austria Speed Period Site
Traffic Calming Mean 85 th Percentile Maximum 1 2 3 4 5 Before 54.0 58.0 60.0 65.0 65.0 After 54.1 48.4 44.1 47.2 40.1 Change 0 -17 -27 -27 -38 Before 62.0 67.0 70.0 76.0 77.0 After 61.0 54.5 50.5 55.2 44.6 Change -2 -19 -28 -27 -42 Before 70.0 88.0 86.0 95.0 97.0 After 76.2 59.3 56.1 65.8 46.9 Change +9 -33 -35 -31 -52 The authors note that Island No. 3 has the additional advantages of: • requiring motorists to reduce speed just prior to leaving the urban area (which may promote a uniform, lower speed throughout the urban area), and • preventing motorists entering the urban area from using the opposing lane (anecdotal observations). Not surprisingly as the deflection increases, so does the speed reduction. Using these results, the following regression models relating the island shape and expected speed were developed: V 85 = 14.797Ln(L/2d)+19.779 R 2 = 0.9098 [10.2] V m = 12.907Ln(L/2d)+17.753 R 2 = 0.9693 [10.3] Where: V 85 = 85 th Percentile speed (km/h) V m = Mean speed (km/h) L = length of island + length of both tapers d = lateral deflection of lane Ewing (1999) Ewing (1999) undertook a comprehensive review of the impacts associated with traffic calming, including the impacts on safety. Using an amalgam of naïve before-after studies that measured crash frequency and included an adjustment for changes in traffic volumes, he identified 55 sites that had been traffic calmed using primarily traffic circles and speed humps. The overall CMF for these calmed sites was 0.96. This report was intended to capture the state of the practice in traffic calming, and not to provide a rigorous overview of the various safety analyses that Ewing collected. Hence, there is no substantial information on site selection procedures, and other information that is required to critically appraise the safety data. Forbes and Gill (2000) Page 128
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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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Page 120 and 121: Synthesis of Safety for Traffic Ope
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
Page 153 and 154: Turn Lanes Vogt determined that a l
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 and 162: Turn Lanes CMF = 1 - 0.7 P lt/d 0.0
Page 163 and 164: Turn Lanes occurred within 250 feet
Page 168 and 169: TABLE 10.3: Speed Changes Resulting
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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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Synthesis of Safety for Traffic Operations - Transports Canada

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