Author: Shauna L. Hallmark
Publisher:
ISBN:
Category : Automobile drivers
Languages : en
Pages : 61
Book Description
Impact of Left-turn Phasing on Older and Younger Drivers at High-speed Signalized Intersections
Author: Shauna L. Hallmark
Publisher:
ISBN:
Category : Automobile drivers
Languages : en
Pages : 61
Book Description
Publisher:
ISBN:
Category : Automobile drivers
Languages : en
Pages : 61
Book Description
Impacts on Safety of Left-turn Treatment at High Speed Signalized Intersections
Author: T. H. Maze
Publisher:
ISBN:
Category : Left-turn lanes
Languages : en
Pages : 94
Book Description
Left-turning traffic is a major source of conflicts at intersections. Though an average of only 10% to 15% of all approach traffic turns left, these vehicles are involved in approximately 45% of all accidents. This report presents the results of research conducted to develop models which estimate approach accident rates at high speed signalized intersections. The objective of the research was to quantify the relationship between traffic and intersection characteristics, and accident potential of different left turn treatments. Geometric, turning movement counts, and traffic signal phasing data were collected at 100 intersections in Iowa using a questionnaire sent to municipalities. Not all questionnaires resulted in complete data and ultimately complete data were derived for 63 intersections providing a database of 248 approaches. Accident data for the same approaches were obtained from the Iowa Department of Transportation Accident Location and Analysis System (ALAS). Regression models were developed for two different dependent variables: 1) the ratio of the number of left turn accidents per approach to million left turning vehicles per approach, and 2) the ratio of accidents per approach to million traffic movements per approach. A number of regression models were developed for both dependent variables. One model using each dependent variable was developed for intersections with low, medium, and high left turning traffic volumes. As expected, the research indicates that protected left turn phasing has a lower accident potential than protected/permitted or permitted phasing. Left turn lanes and multiple lane approaches are beneficial for reducing accident rates, while raised medians increase the likelihood of accidents. Signals that are part of a signal system tend to have lower accident rates than isolated signals. The resulting regression models may be used to determine the likely impact of various left turn treatments on intersection accident rates. When designing an intersection approach, a traffic engineer may use the models to estimate the accident rate reduction as a result of improved lane configurations and left turn treatments. The safety benefits may then be compared to any costs associated with operational effects to the intersection (i.e., increased delay) to determine the benefits and costs of making intersection safety improvements.
Publisher:
ISBN:
Category : Left-turn lanes
Languages : en
Pages : 94
Book Description
Left-turning traffic is a major source of conflicts at intersections. Though an average of only 10% to 15% of all approach traffic turns left, these vehicles are involved in approximately 45% of all accidents. This report presents the results of research conducted to develop models which estimate approach accident rates at high speed signalized intersections. The objective of the research was to quantify the relationship between traffic and intersection characteristics, and accident potential of different left turn treatments. Geometric, turning movement counts, and traffic signal phasing data were collected at 100 intersections in Iowa using a questionnaire sent to municipalities. Not all questionnaires resulted in complete data and ultimately complete data were derived for 63 intersections providing a database of 248 approaches. Accident data for the same approaches were obtained from the Iowa Department of Transportation Accident Location and Analysis System (ALAS). Regression models were developed for two different dependent variables: 1) the ratio of the number of left turn accidents per approach to million left turning vehicles per approach, and 2) the ratio of accidents per approach to million traffic movements per approach. A number of regression models were developed for both dependent variables. One model using each dependent variable was developed for intersections with low, medium, and high left turning traffic volumes. As expected, the research indicates that protected left turn phasing has a lower accident potential than protected/permitted or permitted phasing. Left turn lanes and multiple lane approaches are beneficial for reducing accident rates, while raised medians increase the likelihood of accidents. Signals that are part of a signal system tend to have lower accident rates than isolated signals. The resulting regression models may be used to determine the likely impact of various left turn treatments on intersection accident rates. When designing an intersection approach, a traffic engineer may use the models to estimate the accident rate reduction as a result of improved lane configurations and left turn treatments. The safety benefits may then be compared to any costs associated with operational effects to the intersection (i.e., increased delay) to determine the benefits and costs of making intersection safety improvements.
A Study of the Relationship Between Left Turn Accidents and Driver Age in Arizona
Author: Judson S. Matthias
Publisher:
ISBN:
Category : Left-turn lanes
Languages : en
Pages : 34
Book Description
The findings of this research investigation supports the hypothesis that the elderly driver group is disproportionally represented in left turn accidents. Drivers over 70 averaged more left turn accidents per mile than drivers between the ages of 20 to 69. In addition, left turn accidents represent a much larger proportion of total accidents for drivers over 65 than for any other group. A reduction of permissive left turns could aid older drivers. The permissive type of left turn requires the driver to monitor the traffic light and on-coming opposing traffic for a suitable gap. The resulting lengthened information gathering and decision process of older drivers can lead to the increase in left turn accidents.
Publisher:
ISBN:
Category : Left-turn lanes
Languages : en
Pages : 34
Book Description
The findings of this research investigation supports the hypothesis that the elderly driver group is disproportionally represented in left turn accidents. Drivers over 70 averaged more left turn accidents per mile than drivers between the ages of 20 to 69. In addition, left turn accidents represent a much larger proportion of total accidents for drivers over 65 than for any other group. A reduction of permissive left turns could aid older drivers. The permissive type of left turn requires the driver to monitor the traffic light and on-coming opposing traffic for a suitable gap. The resulting lengthened information gathering and decision process of older drivers can lead to the increase in left turn accidents.
Quantitations of the Impacts of Providing Protected Left Turns at Signalized Intersections
Author: J. Edwin Clark
Publisher:
ISBN:
Category : Electronic traffic controls
Languages : en
Pages : 100
Book Description
Publisher:
ISBN:
Category : Electronic traffic controls
Languages : en
Pages : 100
Book Description
Safety Effects of Left-turn Phasing Schemes at High-speed Intersections
Author: Gary A. Davis
Publisher:
ISBN:
Category : Left-turn lanes
Languages : en
Pages : 69
Book Description
This report describes an effort in estimating crash modification factors (CMFs) associated with different left-turn phasing schemes, at intersections where the major approach speed limit exceeds 40 mph. For installation of signals at previously thru/stop-controlled intersections, rear-end crashes increased while right-angle crashes decreased. Installation of the signal had no effect on either major or minor approach left turn crashes as long as the protected-only left turn phasing was used on the major approaches. At one intersection where a signal was originally installed with permitted/protected phasing on the major approaches, we found evidence for an increase in major approach left-turn crashes, which vanished when the major approach left-turn treatment was changed to protected-only. For several other phasing changes it was not possible to construct an after-treatment data set of sufficient size to permit reliable estimation of an effect. This report also describes a simple simulation model for left-turn cross-path crashes, where a probabilistic gap acceptance model for the turning driver is combined with a standard braking model for the opposing driver. The model characterizes left-turn crashes as resulting when the turning driver accepts a minimal gap and takes an atypically long time complete his/her turn, while the opposing driver takes an atypically long time to react before braking. R reconstruction of an actual fatal crash however was more consistent with the opposing driver reacting normally, but with the turning driver selecting an atypically short gap. Characterizing the rate at which such selection errors occur would then be necessary to accurately predict left-turn crash frequencies.
Publisher:
ISBN:
Category : Left-turn lanes
Languages : en
Pages : 69
Book Description
This report describes an effort in estimating crash modification factors (CMFs) associated with different left-turn phasing schemes, at intersections where the major approach speed limit exceeds 40 mph. For installation of signals at previously thru/stop-controlled intersections, rear-end crashes increased while right-angle crashes decreased. Installation of the signal had no effect on either major or minor approach left turn crashes as long as the protected-only left turn phasing was used on the major approaches. At one intersection where a signal was originally installed with permitted/protected phasing on the major approaches, we found evidence for an increase in major approach left-turn crashes, which vanished when the major approach left-turn treatment was changed to protected-only. For several other phasing changes it was not possible to construct an after-treatment data set of sufficient size to permit reliable estimation of an effect. This report also describes a simple simulation model for left-turn cross-path crashes, where a probabilistic gap acceptance model for the turning driver is combined with a standard braking model for the opposing driver. The model characterizes left-turn crashes as resulting when the turning driver accepts a minimal gap and takes an atypically long time complete his/her turn, while the opposing driver takes an atypically long time to react before braking. R reconstruction of an actual fatal crash however was more consistent with the opposing driver reacting normally, but with the turning driver selecting an atypically short gap. Characterizing the rate at which such selection errors occur would then be necessary to accurately predict left-turn crash frequencies.
An Assessment of Exclusive/permissive Left-turn Signal Phasing
Author: Michael A. Perfater
Publisher:
ISBN:
Category : Automobile driving
Languages : en
Pages : 42
Book Description
More than 70% of motorists returning a questionnaire distributed for the study favored the exclusive/permissive signal, while about 17% said the signal reduced delays, and 30% said it created a hazard. Intersections with one or more right-turn-on-red movements seemed especially susceptible to vehicular conflicts. The ratios of accidents involving left-turning vehicles to all accidents at intersections appeared to increase after the E/P signals were installed.
Publisher:
ISBN:
Category : Automobile driving
Languages : en
Pages : 42
Book Description
More than 70% of motorists returning a questionnaire distributed for the study favored the exclusive/permissive signal, while about 17% said the signal reduced delays, and 30% said it created a hazard. Intersections with one or more right-turn-on-red movements seemed especially susceptible to vehicular conflicts. The ratios of accidents involving left-turning vehicles to all accidents at intersections appeared to increase after the E/P signals were installed.
Traffic Engineering Handbook
Author: ITE (Institute of Transportation Engineers)
Publisher: John Wiley & Sons
ISBN: 1118762304
Category : Technology & Engineering
Languages : en
Pages : 688
Book Description
Get a complete look into modern traffic engineering solutions Traffic Engineering Handbook, Seventh Edition is a newly revised text that builds upon the reputation as the go-to source of essential traffic engineering solutions that this book has maintained for the past 70 years. The updated content reflects changes in key industry standards, and shines a spotlight on the needs of all users, the design of context-sensitive roadways, and the development of more sustainable transportation solutions. Additionally, this resource features a new organizational structure that promotes a more functionally-driven, multimodal approach to planning, designing, and implementing transportation solutions. A branch of civil engineering, traffic engineering concerns the safe and efficient movement of people and goods along roadways. Traffic flow, road geometry, sidewalks, crosswalks, cycle facilities, shared lane markings, traffic signs, traffic lights, and moreāall of these elements must be considered when designing public and private sector transportation solutions. Explore the fundamental concepts of traffic engineering as they relate to operation, design, and management Access updated content that reflects changes in key industry-leading resources, such as the Highway Capacity Manual (HCM), Manual on Uniform Traffic Control Devices (MUTCD), AASSHTO Policy on Geometric Design, Highway Safety Manual (HSM), and Americans with Disabilities Act Understand the current state of the traffic engineering field Leverage revised information that homes in on the key topics most relevant to traffic engineering in today's world, such as context-sensitive roadways and sustainable transportation solutions Traffic Engineering Handbook, Seventh Edition is an essential text for public and private sector transportation practitioners, transportation decision makers, public officials, and even upper-level undergraduate and graduate students who are studying transportation engineering.
Publisher: John Wiley & Sons
ISBN: 1118762304
Category : Technology & Engineering
Languages : en
Pages : 688
Book Description
Get a complete look into modern traffic engineering solutions Traffic Engineering Handbook, Seventh Edition is a newly revised text that builds upon the reputation as the go-to source of essential traffic engineering solutions that this book has maintained for the past 70 years. The updated content reflects changes in key industry standards, and shines a spotlight on the needs of all users, the design of context-sensitive roadways, and the development of more sustainable transportation solutions. Additionally, this resource features a new organizational structure that promotes a more functionally-driven, multimodal approach to planning, designing, and implementing transportation solutions. A branch of civil engineering, traffic engineering concerns the safe and efficient movement of people and goods along roadways. Traffic flow, road geometry, sidewalks, crosswalks, cycle facilities, shared lane markings, traffic signs, traffic lights, and moreāall of these elements must be considered when designing public and private sector transportation solutions. Explore the fundamental concepts of traffic engineering as they relate to operation, design, and management Access updated content that reflects changes in key industry-leading resources, such as the Highway Capacity Manual (HCM), Manual on Uniform Traffic Control Devices (MUTCD), AASSHTO Policy on Geometric Design, Highway Safety Manual (HSM), and Americans with Disabilities Act Understand the current state of the traffic engineering field Leverage revised information that homes in on the key topics most relevant to traffic engineering in today's world, such as context-sensitive roadways and sustainable transportation solutions Traffic Engineering Handbook, Seventh Edition is an essential text for public and private sector transportation practitioners, transportation decision makers, public officials, and even upper-level undergraduate and graduate students who are studying transportation engineering.
Safety and Operations Assessment of Various Left-turn Phasing Strategies
Investigation of Older Driver Crashes at High-speed Multi-lane Intersections
Intersection Negotiation Problems of Older Drivers: Background synthesis on age and intersection driving difficulties
Author:
Publisher:
ISBN:
Category : Older automobile drivers
Languages : en
Pages : 144
Book Description
Publisher:
ISBN:
Category : Older automobile drivers
Languages : en
Pages : 144
Book Description