Synthesis of Safety for Traffic Operations - Transports Canada

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Synthesis of Safety for Traffic Operations March 2003 lanes on the minor road; the signalized intersections had two-lanes on all approaches. Generalized linear regression using a negative binomial distribution was used to model all crashes within 250 feet of the intersection on the main road, and with 100 and 250 feet of the intersection on the side road, in California and Michigan, respectively. The resultant models are as shown in Equations 3.4 to 3.5. For four lane main roads, with stop-controlled two-lane minor roads and three approaches: N = 0.000000192 ADT m 1.433 ADT s 0.269 exp(-0.0612M + 0.0560D) [3.4] where: N = Number of crashes per year ADT m = Average two-way major road traffic per day ADT s = Average two-way side street traffic per day M = Median width on the major road (metres) D = Number of driveways on the major road within 76 metres of the intersection centre For four lane main roads, with stop-controlled two-lane minor roads and four approaches: N = 0.0000777 ADT m 0.850 ADT s 0.329 exp(0.110PL – 0.484L) [3.5] where: N = Number of crashes per year ADT m = Average two-way major road traffic per day ADT s = Average two-way side street traffic per day PL = Proportion of peak hour traffic approaching on the major road that is turning left (%) L = 0 if major road has no left-turn lane; 1 if at least one left-turn lane. For the signalized intersection of two-lane roads with four approaches: N = 0.000955 ADT 0.620 m ADT 0.395 s exp(-0.0142PL s + 0.0315T) * exp( – 0.675L T + 0.130V) [3.6] where: N = Number of crashes per year ADT m = Average two-way major road traffic per day ADT s = Average two-way side street traffic per day PL s = Proportion of peak hour traffic approaching on the side street that is turning left (%) T = Proportion of peak hour traffic approaching the intersection that consists of trucks (%) L T = 0 if the major road does not have a protected left turn; 1 if the major road has at least one protected turn phase V = 0.5 * (V m + V s ) Page 21
Intersection Control V m = the sum of the absolute percent grade change per 100 feet for each vertical curve along the major road, any portion of which is within 800 feet of the intersection centre, divided by the number of such curves V s = the sum of the absolute percent grade change per 100 feet for each vertical curve along the side street, any portion of which is within 800 feet of the intersection centre, divided by the number of such curves The above models by themselves cannot be used to determine the safety impacts of a change in intersection control. Nonetheless, they provide good estimates of the long-term safety of the three intersection types. The SPFs for the unsignalized locations may be combined with the crash record at an existing intersection to better predict the long-term safety of the location. The SPF for the signalized intersection may be used similarly, or to predict the safety performance of an unsignalized intersection if it is signalized. To combine the SPF with the crash record of a site, the “overdispersion parameter” (k) must be know, they are shown in Table 3.10. For a description on how to combine SPF estimates with crash records see Appendix D. TABLE 3.10: Overdispersion Parameters from Vogt (1999) Equation k 3.2 0.389 3.3 0.458 3.4 0.116 Transport Research Laboratory (2000) The Transport Research Laboratory (2000) in the United Kingdom has examined the safety effects of signal installation as part of a program to monitor the safety impacts of various actions undertaken by local road authorities. The Transport Research Laboratory (TRL) maintains the information about local road safety improvements in the Monitoring Of Local Authority Safety SchemES (MOLASSES) database. This database has been active since 1991 and contains information on a variety of local road safety improvements. Data is voluntarily inputted into the database by local road authorities. The data collected include • Average daily traffic • Speed limit • Setting (i.e., urban or rural) • Location (type of intersection, type road section, or area-wide) Page 22
Page 1 and 2: Transport Canada Transports Canada
Page 4: Synthesis Of Safety For Traffic Ope
Page 8 and 9: DISCLAIMER The material presented h
Page 10 and 11: EXECUTIVE SUMMARY Traffic operation
Page 12 and 13: Synthesis of Safety for Traffic Ope
Page 16 and 17: TABLE OF CONTENTS DISCLAIMER REJET
Page 20 and 21: LIST OF TABLES TABLE 3.1: Crash Rat
Page 24: Chapter 1: Chapter 1: Introductio I
Page 27 and 28: Introduction Before proceeding, a f
Page 29 and 30: Introduction Literature regarding t
Page 31 and 32: Introduction The current science of
Page 33 and 34: Introduction adequate size control
Page 35 and 36: Introduction In concluding this sec
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Page 45 and 46: Intersection Control TABLE 3.3: Cra
Page 47 and 48: Intersection Control TABLE 3.5: CMF
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Page 55 and 56: Intersection Control Region of Durh
Page 57 and 58: Intersection Control TABLE 3.17: CM
Page 59 and 60: Intersection Control The predictor
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Page 79 and 80: Intersection Control The CMFs are 0
Page 81 and 82: Intersection Control also examined
Page 83 and 84: Intersection Control Shebeeb (1995)
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Synthesis of Safety for Traffic Ope
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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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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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