Evaluating The Effects Of Prohibiting Left Turns And The Resulting U Turn Movement

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Evaluating the Effects of Prohibiting Left Turns and the Resulting U-turn Movement

Author : Mashrur A. Chowdhury
Publisher :
ISBN 13 :
Total Pages : 90 pages
Book Rating : 4.3/5 (555 download)

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Book Synopsis Evaluating the Effects of Prohibiting Left Turns and the Resulting U-turn Movement by : Mashrur A. Chowdhury

Download or read book Evaluating the Effects of Prohibiting Left Turns and the Resulting U-turn Movement written by Mashrur A. Chowdhury and published by . This book was released on 2003 with total page 90 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this research was to evaluate the operational and safety effects of restricting direct left turns from a driveway and providing alternatives to accommodate the left turn deterred traffic. This study was conducted in three phases: survey of state agencies, operational analysis, and safety assessment. Very little operational difference was found between no restrictions on direct left turns versus the restrictions with the U-turn alternative movements from site to site. While changes in the traffic volumes on the mainline had an impact in specific instances, no definite trends were apparent. As a result of all findings in this study, it is proposed that alternatives must be evaluated on a site-by-site basis. This study also found the jughandle design to be a superior alternative for accommodating left-turn deterred traffic for multi-lane divided and undivided sites compared to mid-block or intersection U-turns. The safety assessment revealed that a right turn followed by a U-turn movement is safer than the direct left turn.

Operational Evaluation of Right Turns Followed by U-turns at Signalized Intersections (6 Or More Lanes) as an Alternative to Direct Left Turns

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Author :
Publisher :
ISBN 13 :
Total Pages : 230 pages
Book Rating : 4.3/5 (555 download)

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Book Synopsis Operational Evaluation of Right Turns Followed by U-turns at Signalized Intersections (6 Or More Lanes) as an Alternative to Direct Left Turns by :

Download or read book Operational Evaluation of Right Turns Followed by U-turns at Signalized Intersections (6 Or More Lanes) as an Alternative to Direct Left Turns written by and published by . This book was released on 2005 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Evaluation of the Operational Effects of U-turn Movement

Author : Pan Liu
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (159 download)

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Book Synopsis Evaluation of the Operational Effects of U-turn Movement by : Pan Liu

Download or read book Evaluation of the Operational Effects of U-turn Movement written by Pan Liu and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: In Florida, the increased installation of non-traversable medians and directional median opening has produced an increased number of U-turns on multilane highways. Arguments have been advanced by some opponents of median modification projects that the increased numbers of U-turns may result in safety and operational problems on multilane highways. The primary objective of this study is to evaluate the operational effects of U-turn movement on multilane roadways. To achieve this research objective, extensive data were collected. Field measurements were conducted at 40 sites in the Tampa Bay area of Florida to collect traffic operations data. Besides, the crash histories of 179 selected roadway segments in central Florida were investigated. Statistical analysis was conducted based on the collected traffic operations data and crash data to quantitatively evaluate the operational performance of U-turn movement. Delay and travel time were compared for different driveway left-turn alternatives that are widely used in Florida and nationally. Crash rate models were developed to evaluate how the separation distance between a driveway exit and the downstream U-turn bay impacts the safety performance of vehicles making right-turns followed by U-turns (RTUT). With the crash data analysis results, the minimum separation distances under different roadway conditions were determined to facilitate driver use of RTUTs. The capacity of U-turn movement was analyzed under two different situations: (1) U-turns are provided at a signalized intersection; and (2) U-turns are provided at an unsignalized intersection. Adjustment factors were developed to quantify the impacts of the presence of U-turning vehicles on the capacity of a signalized intersection. The critical gaps and follow-up time for U-turn movement at unsignalized intersections were estimated. With the estimated critical gaps and follow-up time, the Harders model was used to determine the capacity of U-turn movement at an unsignalized intersection. This study also looks extensively at the minimum roadway width and median width required by vehicles to perform U-turn maneuvers on 4-lane divided roadways. It was found that a roadway width of 46 ft is generally sufficient for most types of design vehicles (except heavy vehicles) to perform a continuous U-turn maneuver without impedance.

Safety Evaluation of Right Turns Followed by U-turns as an Alternative to Direct Left Turns: Operational evaluation of right turns followed by U-turns as an alternative to direct left turns

Download Safety Evaluation of Right Turns Followed by U-turns as an Alternative to Direct Left Turns: Operational evaluation of right turns followed by U-turns as an alternative to direct left turns PDF Online Free

Author :
Publisher :
ISBN 13 :
Total Pages : 230 pages
Book Rating : 4.3/5 (555 download)

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Book Synopsis Safety Evaluation of Right Turns Followed by U-turns as an Alternative to Direct Left Turns: Operational evaluation of right turns followed by U-turns as an alternative to direct left turns by :

Download or read book Safety Evaluation of Right Turns Followed by U-turns as an Alternative to Direct Left Turns: Operational evaluation of right turns followed by U-turns as an alternative to direct left turns written by and published by . This book was released on 2001 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Safety Evaluation of Right Turns Followed by U-turns (4 Lanes Arterials) as an Alternative to Direct Left Turns

Author : Jian John Lu
Publisher :
ISBN 13 :
Total Pages : 260 pages
Book Rating : 4.3/5 (555 download)

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Book Synopsis Safety Evaluation of Right Turns Followed by U-turns (4 Lanes Arterials) as an Alternative to Direct Left Turns by : Jian John Lu

Download or read book Safety Evaluation of Right Turns Followed by U-turns (4 Lanes Arterials) as an Alternative to Direct Left Turns written by Jian John Lu and published by . This book was released on 2005 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Effects of U-turns on Capacity at Signalized Intersections and Simulation of U-turning Movement by Synchro

Author : Xiaodong Wang
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (47 download)

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Book Synopsis Effects of U-turns on Capacity at Signalized Intersections and Simulation of U-turning Movement by Synchro by : Xiaodong Wang

Download or read book Effects of U-turns on Capacity at Signalized Intersections and Simulation of U-turning Movement by Synchro written by Xiaodong Wang and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: The primary objective of this study is to evaluate the operational effects of U-turn movement at signalized intersections. More specifically, the research objectives include the following parts: To identify the factors affecting the operational performance of U-turning vehicles. In this case, we are particularly interested in the U-turn speeds of U-turning vehicles; To evaluate the impacts of U-turns on capacity of signalized intersections, and; To simulate U-turn movement at signalized intersections using Synchro and validate the simulation results. To achieve the research objectives, extensive field data collection work was conducted at sixteen selected sites at Tampa Bay area of Florida. The data collected in the field include: U-turning speed; Left turning speed; Turning radius Queue discharge time; Control delay; Hourly traffic volume, and; Percentage of U- turning vehicles in left turn lane. Based on the collected field data, a linear regression model was developed to identify the factors affecting the turning speeds of U-turning vehicles at signalized intersections. The model shows the turning speed is significantly impacted by the turning radius and the speed of U-turning vehicles increases with the increase of turning radius. On the basis of field data field data collection, a regression model was developed to estimate the relationship between the average queue discharge time for each turning vehicle and the various percentages of U-turning vehicles in the left turn traffic stream. Adjustment factors for various percentages of U-turning vehicles were also developed by using the regression model. The adjustment factors developed in this study can be directly used to estimate the capacity reduction due to the presence of various percentages of U-turning vehicles at a signalized intersection. The developed adjustment factors were used to improve the simulation of U-turn movement at signalized intersection by using Synchro. The simulation model was calibrated and validated by field data. It was found that using the developed adjustment factors will greatly improve the accuracy of the simulation results for U-turn movement.

Safety Evaluation of Right Turns Followed by U-turns as an Alternative to Direct Left Turns: Crash data analysis

Author : Jian John Lu
Publisher :
ISBN 13 :
Total Pages : 158 pages
Book Rating : 4.3/5 (555 download)

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Book Synopsis Safety Evaluation of Right Turns Followed by U-turns as an Alternative to Direct Left Turns: Crash data analysis by : Jian John Lu

Download or read book Safety Evaluation of Right Turns Followed by U-turns as an Alternative to Direct Left Turns: Crash data analysis written by Jian John Lu and published by . This book was released on 2001 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt:

A Performance Accessment of the Elimination of Left-turns at Selected Intersections

Author : Xinyun Cao
Publisher :
ISBN 13 : 9781321207545
Total Pages : 77 pages
Book Rating : 4.2/5 (75 download)

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Book Synopsis A Performance Accessment of the Elimination of Left-turns at Selected Intersections by : Xinyun Cao

Download or read book A Performance Accessment of the Elimination of Left-turns at Selected Intersections written by Xinyun Cao and published by . This book was released on 2014 with total page 77 pages. Available in PDF, EPUB and Kindle. Book excerpt: For most signalized intersections, left-turn movements are considered as a primary contributor to intersection delay. The concept of eliminating left-turn movements is now feasible with the rise of GPS-based routing which will allow the active routing of vehicles in networks with reduced left turns. This research seeks to estimate the impact of left turn reductions on overall travel time and left turn delay at intersections. The research objective is to evaluate the effect of left turn movement elimination in sample networks. The type of intersections considered is restricted to a grid network but is defined by the roadway hierarchy. A sample network was selected based on a real world network and reflecting observed volumes, travel times, and delays. The analysis approach is to eliminate left turn movements in three types of intersections by applying turn prohibitions and adjusting cycle lengths and turn penalties on other movements. Network performance is then assessed based on delay reduction, total travel time, and fuel consumption. It was concluded that selective reduction of left turn movements can improve network performance.

Safety Evaluation of Right Turns Followed by U-turns at Signalized Intersections (6 Or More Lane Arterials) as an Alternative to Direct Left Turns

Download Safety Evaluation of Right Turns Followed by U-turns at Signalized Intersections (6 Or More Lane Arterials) as an Alternative to Direct Left Turns PDF Online Free

Author : Lu, Jian John Lu
Publisher :
ISBN 13 :
Total Pages : 172 pages
Book Rating : 4.3/5 (555 download)

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Book Synopsis Safety Evaluation of Right Turns Followed by U-turns at Signalized Intersections (6 Or More Lane Arterials) as an Alternative to Direct Left Turns by : Lu, Jian John Lu

Download or read book Safety Evaluation of Right Turns Followed by U-turns at Signalized Intersections (6 Or More Lane Arterials) as an Alternative to Direct Left Turns written by Lu, Jian John Lu and published by . This book was released on 2005 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Safety Impacts of Right Turns Followed by U-turns

Author : Fatih Pirinccioglu
Publisher :
ISBN 13 : 9781109978568
Total Pages : 131 pages
Book Rating : 4.9/5 (785 download)

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Book Synopsis Safety Impacts of Right Turns Followed by U-turns by : Fatih Pirinccioglu

Download or read book Safety Impacts of Right Turns Followed by U-turns written by Fatih Pirinccioglu and published by . This book was released on 2007 with total page 131 pages. Available in PDF, EPUB and Kindle. Book excerpt: Impacts of separation distance on safety of RTUT movements were investigated by a regression model. The model investigated impacts of U-turn bay locations and the number of lanes on major arterial on separation distance requirements. The model results indicated that U-turn bays located at signalized intersections and greater number of lanes on major arterials increases the minimum separation distance requirements.

Determination of the Offset Distance Between Driveway Exits and Downstream U-turn Locations for Vehicles Making Right Turns Followed by U-turns

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Author : Jian John Lu
Publisher :
ISBN 13 :
Total Pages : 194 pages
Book Rating : 4.3/5 (555 download)

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Book Synopsis Determination of the Offset Distance Between Driveway Exits and Downstream U-turn Locations for Vehicles Making Right Turns Followed by U-turns by : Jian John Lu

Download or read book Determination of the Offset Distance Between Driveway Exits and Downstream U-turn Locations for Vehicles Making Right Turns Followed by U-turns written by Jian John Lu and published by . This book was released on 2005 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt: Florida increasingly uses restrictive medians and directional median openings on multi-lane highways to manage left turn egress maneuvers from driveways and side streets. By installing non-traversable medians and replacing full median openings with directional median openings at various locations, Florida prohibits direct left-turn exits onto some major arterials. The purpose of this research was to evaluate how the offset distance between driveway exits and downstream median openings or signalized intersections impacts traffic operational and safety performance. The primary objective is to determine optimum offset distances to facilitate driver use of Right Turn Followed by a U-Turn (RTUT) maneuvers, specifically investigating (1) traffic operational performance, based on the evaluation of vehicle travel time at various offset distances, and (2) safety performance, based on the evaluation of traffic conflicts and crash data. The focus of this research was on urban or suburban multi-lane divided arterials. Researchers studied the impacts of offset distance under four different scenarios: 4-lane divided roadways accommodating U-turns at median openings, 4-lane divided roadways accommodating U-turns at signalized intersections, 6 or more-lane divided roadways accommodating U-turns at median openings, and 6 or more-lane divided roadways accommodating U-turns at signalized intersections.

Operational and Safety Impacts of U-Turns at Signalized Intersections

Author :
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (656 download)

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Book Synopsis Operational and Safety Impacts of U-Turns at Signalized Intersections by :

Download or read book Operational and Safety Impacts of U-Turns at Signalized Intersections written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: With rapidly growing urban areas and construction of new developments, efficient access to the roadway network becomes a relevant issue. In the effort to balance safety, mobility, and access, many transportation officials are in favor of designs that employ raised medians on the main road. However, this decision draws much controversy from those opposed to the lack of direct access that comes with raised median designs. One of the issues in this controversy is the effect of increased U-turns at adjacent intersections. The purpose of this research is to determine the operational and safety effects of U-turns at signalized intersections. The operational analysis involved measurements of vehicle headways in exclusive left turn lanes at 14 intersections. By regression analysis, I obtained an equation to estimate saturation flow reduction based on intersection characteristics. This equation indicates a 1.8% saturation flow rate loss in the left turn lane for every 10% increase in U-turn percentage and an additional 1.5% loss for every 10% U-turns if the U-turning movement is opposed by protected right turn overlap from the cross street. The safety study involved a set of 78 intersections. Fifty-four sites were chosen randomly, and twenty-four sites were selected based on their reputation as U-turn 'problem sites'. Although the group of study sites was purposely biased toward sites with high U-turn percentages, the study found that 65 of the 78 sites did not have any collisions involving U-turns in the three-year study period, and the U-turn collisions at the remaining 13 sites ranged from 0.33 to 3.0 collisions per year. Sites with double left turn lanes, protected right turn overlap, or high left turn and conflicting right turn traffic volumes were found to have a significantly greater number of U-turn collisions.

NCHRP Report 524

Author :
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (16 download)

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Book Synopsis NCHRP Report 524 by :

Download or read book NCHRP Report 524 written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Impacts on Safety of Left-turn Treatment at High Speed Signalized Intersections

Author : T. H. Maze
Publisher :
ISBN 13 :
Total Pages : 94 pages
Book Rating : 4.3/5 (555 download)

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Book Synopsis Impacts on Safety of Left-turn Treatment at High Speed Signalized Intersections by : T. H. Maze

Download or read book Impacts on Safety of Left-turn Treatment at High Speed Signalized Intersections written by T. H. Maze and published by . This book was released on 1994 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Geometric Design and the Effects on Traffic Operations, 2005

Author :
Publisher :
ISBN 13 :
Total Pages : 96 pages
Book Rating : 4.:/5 (1 download)

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Book Synopsis Geometric Design and the Effects on Traffic Operations, 2005 by :

Download or read book Geometric Design and the Effects on Traffic Operations, 2005 written by and published by . This book was released on 2005 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Traffic Engineering Handbook

Author : ITE (Institute of Transportation Engineers)
Publisher : John Wiley & Sons
ISBN 13 : 1118762304
Total Pages : 688 pages
Book Rating : 4.1/5 (187 download)

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Book Synopsis Traffic Engineering Handbook by : ITE (Institute of Transportation Engineers)

Download or read book Traffic Engineering Handbook written by ITE (Institute of Transportation Engineers) and published by John Wiley & Sons. This book was released on 2016-01-26 with total page 688 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 more—all 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.

Roundabouts

Author : Lee August Rodegerdts
Publisher : Transportation Research Board
ISBN 13 : 0309155118
Total Pages : 407 pages
Book Rating : 4.3/5 (91 download)

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Book Synopsis Roundabouts by : Lee August Rodegerdts

Download or read book Roundabouts written by Lee August Rodegerdts and published by Transportation Research Board. This book was released on 2010 with total page 407 pages. Available in PDF, EPUB and Kindle. Book excerpt: TRB's National Cooperative Highway Research Program (NCHRP) Report 672: Roundabouts: An Informational Guide - Second Edition explores the planning, design, construction, maintenance, and operation of roundabouts. The report also addresses issues that may be useful in helping to explain the trade-offs associated with roundabouts. This report updates the U.S. Federal Highway Administration's Roundabouts: An Informational Guide, based on experience gained in the United States since that guide was published in 2000.