Impacts On Safety Of Left Turn Treatment At High Speed Signalized Intersections
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Impacts On Safety Of Left Turn Treatment At High Speed Signalized Intersections
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Author : T. H. Maze
language : en
Publisher:
Release Date : 1994
Impacts On Safety Of Left Turn Treatment At High Speed Signalized Intersections written by T. H. Maze and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1994 with Left-turn lanes categories.
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.
Capacity And Operational Effects Of Midblock Left Turn Lanes
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Author : James A. Bonneson
language : en
Publisher: Transportation Research Board
Release Date : 1997
Capacity And Operational Effects Of Midblock Left Turn Lanes written by James A. Bonneson and has been published by Transportation Research Board this book supported file pdf, txt, epub, kindle and other format this book has been release on 1997 with Technology & Engineering categories.
The objective of this research project was to develop a methodology for evaluating alternative midblock left-turn treatments on urban and suburban arterials. The methodology had to be applicable to three common midblock left-turn treatments: the raised-curb median, the flush median with two-way left-turn lane (TWLTL) delineation, and the undivided cross section. The methodology developed for this research focuses on the evaluation of midblock street segments on urban and suburban arterials. The basis for NCHRP Report 395.
Safety Effectiveness Of Intersection Left And Right Turn Lanes
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Author : Douglas W. Harwood
language : en
Publisher:
Release Date : 2002
Safety Effectiveness Of Intersection Left And Right Turn Lanes written by Douglas W. Harwood and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2002 with Roads categories.
This report presents the results of research that performed a well-designed before-after evaluation of the safety effects of providing left- and right-turn lanes for at-grade intersections. Geometric design, traffic control, traffic volume, and traffic accident data were gathered for a total of 280 improved intersections, as well as 300 similar intersections that were not improved during the study period. The types of improvement projects evaluated included installation of added left-turn lanes, added right-turn lanes, and extension of the length of existing left- or right-turn lanes. An observational before-after evaluation of these projects was performed using several alternative evaluation approaches. The three contrasting approaches to before-after evaluation used were the yoked comparison or matched-pair approach, the comparison group approach, and the Empirical Bayes approach. The research not only evaluated the safety effectiveness of left- and right-turn lane improvements, but also compared the performance of these three alternative approaches in making such evaluations. The research developed quantitative safety effectiveness measures for installation design improvements involving added left-turn lanes and added right-turn lanes. The research concluded that the Empirical Bayes method provided the most accurate and reliable results. Further use of this method is recommended.
State Of The Practice In Highway Access Management
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Author : Jerome S. Gluck
language : en
Publisher: Transportation Research Board
Release Date : 2010
State Of The Practice In Highway Access Management written by Jerome S. Gluck and has been published by Transportation Research Board this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with Highway engineering categories.
This synthesis reports how various agencies have acted on the various components of an access management program, what have been barriers to action, and how new efforts might improve implementation of access management strategies. Primary focus areas considered are legal and legislative bases, contents of policies and programs, implementation aspects, reported effectiveness of program implementation, and profiles of contemporary practice. This synthesis reports on the state of the practice with respect to planning, highway design, development review and permitting, and other focus areas where access management is typically incorporated. The emphasis is placed on states, but counties, municipalities, and metropolitan planning organizations are also considered.
Low Cost Safety Enhancements For Stop Controlled And Signalized Intersections
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Author :
language : en
Publisher:
Release Date : 2009
Low Cost Safety Enhancements For Stop Controlled And Signalized Intersections written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with Roads categories.
"The purpose of this document is to present information on suggested effective, low-cost intersection countermeasures developed using intersection safety research results and input from an intersection safety expert panel. These low-cost countermeasures can be applied to a large number of intersections with a high frequency of crashes using a systematic approach. The net impact of such an approach can produce significant reductions in statewide intersection crashes, fatalities, and serious injuries. Low-cost countermeasures are defined as those ranging from $1,000 to $50,000 per intersection"--Page 4
Safety Impact Of Permitting Right Turn On Red
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Author : Richard P. Compton
language : en
Publisher:
Release Date : 1994
Safety Impact Of Permitting Right Turn On Red written by Richard P. Compton and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1994 with Right turn on red categories.
The Energy Policy Act of 1992 required NHTSA to conduct a study of the safety impact of permitting right and left turns on red lights. The report presents a brief summary of the current status of State implementation of laws permitting right and left turns at red lights, a brief review of previous research, and the results of analyses of currently available data assessing the safety impact of permitting right turns on red.
Evaluation Of Detector Placement For High Speed Approaches To Signalized Intersections
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Author : Dan R. Middleton
language : en
Publisher:
Release Date : 1997
Evaluation Of Detector Placement For High Speed Approaches To Signalized Intersections written by Dan R. Middleton and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1997 with Detectors categories.
Toolbox To Assess Tradeoffs Between Safety Operations And Air Quality For Intersection And Access Management Strategies
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Author :
language : en
Publisher:
Release Date : 2008
Toolbox To Assess Tradeoffs Between Safety Operations And Air Quality For Intersection And Access Management Strategies written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008 with Air quality categories.
Significant transportation agency resources are allocated to meet maintenance, operations, safety, and air quality goals. Although there is a significant amount of overlap between these areas, decisions to meet agency goals in one area often do not consider goals in the others and, as a result, miss opportunities to leverage funds and make better informed decisions overall. There are a number of areas of overlap between capital improvements designed to improve operations, maintenance, safety, and air quality goals that provide a rich opportunity to leverage funds and use resources more cost-effectively while meeting agency goals in two or more of the areas. The objective of this research is to develop analytical tools that can efficiently evaluate common capital projects used to meet agency goals in one area (operations, safety, air quality, and maintenance) but that also have a significant impact on the others.
Report
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Author :
language : en
Publisher:
Release Date : 2008
Report written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008 with Highway research categories.
Traffic Safety Effects Of Fuel Shortage And Speed Limits A Bibliography
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Author : L. Flynn (comp)
language : en
Publisher:
Release Date : 1976
Traffic Safety Effects Of Fuel Shortage And Speed Limits A Bibliography written by L. Flynn (comp) and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1976 with categories.