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Development Of Left Turn Lane Guidelines At Signalized And Unsignalized Intersections Using An Event Based Simulation Model
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Book Synopsis Development of Left-turn Lane Guidelines for Signalized and Unsignalized Intersections by :
Download or read book Development of Left-turn Lane Guidelines for Signalized and Unsignalized Intersections written by and published by . This book was released on 2004 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is generally accepted that the level of service (LOS) at intersections significantly affects the overall LOS of the road system. It is also known that the LOS at an intersection can be adversely affected by frequently allowing left-turning vehicles to block through traffic. In addition, crash rates tend to be higher at intersections than on through sections of a road. The separation of left-turning vehicles from through traffic is therefore an important condition for the safe and effective operation of intersections. Existing guidelines for installing left-turn lanes have several limitations. They are mainly based on the traffic volumes at the intersection, and they use deterministic models with fixed gap acceptance and/or left-turn maneuver times. In addition, the guidelines for left-turn lanes for unsignalized intersections and signalized intersections must be specific for the type of intersection. In this study, new left-turn guidelines for both unsignalized and signalized intersections were developed on the basis of well-validated event-based simulation programs. Guidelines for unsignalized intersections were based on the percentage of left turns blocking through vehicles, whereas the guidelines for signalized intersections were developed using a minimum left-turn volume of either 85% left-turn capacity or LOS E delay (55 seconds/vehicle). In addition to the general guidelines, a prioritization tool that can be used to prioritize candidate intersections was developed. The prioritization tool accounts for both operational and safety aspects.
Book Synopsis Development of Left-turn Lane Guidelines at Signalized and Unsignalized Intersections Using an Event-based Simulation Model by : Vijayendra Rao Lakkundi
Download or read book Development of Left-turn Lane Guidelines at Signalized and Unsignalized Intersections Using an Event-based Simulation Model written by Vijayendra Rao Lakkundi and published by . This book was released on 2003 with total page 302 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Development of Warrants for Installation of Dual Right-turn Lanes at Signalized Intersections by : Yi Qi
Download or read book Development of Warrants for Installation of Dual Right-turn Lanes at Signalized Intersections written by Yi Qi and published by . This book was released on 2012 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: Right-turn lanes provide space for the deceleration and storage of right-turn vehicles, and separate turning vehicles from through movements. Dual right-turn lanes are increasingly used at urban intersections primarily for two reasons: (1) to accommodate high right-turn demands and avoid turn-pocket overflows, and/or (2) to prevent right-turn vehicles that exit from a nearby upstream freeway off-ramp (on the left of the roadway) from abruptly changing too many lanes toward the right-turn lane at the intersection. In addition, a number of other factors may affect the decisions on the installation of dual right-turn lanes. However, warrants for dual right lane installation are almost non-existent, leaving traffic engineers to rely on engineering judgment. This research aims to develop warrants for installation of dual right-turn lanes at signalized intersections. Both the operational and safety benefits/costs were analyzed by surveying traffic engineers and by conducting traffic simulation-based analysis. Microscopic traffic simulation model, VISSIM, was used to quantify the operation benefits and Surrogate Safety Assessment Model (SSAM) developed by Siemens was used to analyze the safety gains due to installation of dual right-turn lanes.
Book Synopsis Left-turn Lane Design and Operation by :
Download or read book Left-turn Lane Design and Operation written by and published by . This book was released on 2008 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis A Decision Support System and New Warrants for Left Turn Lane Installation at Unsignalised Intersections by : Sarang S. Ranade
Download or read book A Decision Support System and New Warrants for Left Turn Lane Installation at Unsignalised Intersections written by Sarang S. Ranade and published by . This book was released on 2007 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt: Accommodating left turns at un-signalized intersections is one of the most challenging problems in traffic engineering. Over the last forty years, a small number of studies developed guidelines for traffic engineers to help decide when a left turn lane is warranted for a given situation. Building on these previous attempts, the current study not only develops warrants for the left turn lane at an unsignalised intersection but also a refined decision support system (DSS) for assessing the likely benefits of left-turn lane installations. The developed warrants use total delay (veh.sec/hour) and total stops (number) on the subject link as the warrant criteria, and the trigger level differs by road category. The developed DSS on the other hand, is designed to predict the likely benefits of installation of an exclusive left turn lane at an un-signalized intersection. The benefits are measured in terms of delay savings, reductions in the total number of stops, increases in fuel efficiency, and reductions in emissions. The first step in developing the left turn lane warrants and the DSS was to use microscopic simulation to model several real-world un-signalized intersections with different geometric. After carefully calibrating these models, several scenarios which cover a wide range of operational conditions (opposing, advancing, left turning volumes speed etc,) were simulated. The output fiom these simulation runs was then used to train a set of Multi-layer Perceptron Neural Networks (NNs), and to generalize the results from the models' runs. These NNs can therefore serve as a DSS for predicting the likely benefits of left turn lane installations. In addition, new warrants were developed for left turn lane installations based on delay as well as percent stops as warrant criteria.
Book Synopsis Development of Safety-based Level-of-service Criteria for Isolated-signalized Intersections by : Tae-Jun Ha
Download or read book Development of Safety-based Level-of-service Criteria for Isolated-signalized Intersections written by Tae-Jun Ha and published by . This book was released on 1994 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Development of Left-turn Lane Warrants for Unsignalized Intersections by :
Download or read book Development of Left-turn Lane Warrants for Unsignalized Intersections written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Left-turn movements at intersections, including driveways - especially movements that are made from lanes that are shared with through traffic - cause delays and adversely impact safety. Although left-turn warrants have been updated, many agencies still use research performed by M. Harmelink from the mid-1960s. While most states use procedures that are based on Harmelink, a number of limitations of Harmelink's procedure have been identified. Economic analysis can provide a useful method for combining traffic operations and safety benefits of left-turn lanes to identify situations in which left-turn lanes are and are not justified economically. This project used a benefit-cost approach to determine when a left-turn lane would be justified. The steps included simulation to determine delay savings from installing a left-turn lane, crash costs and crash reduction savings determined from safety performance functions and accident modification factors available in the "Highway Safety Manual," and construction costs. Left-turn lane warrants were developed for rural two-lane highways, rural four-lane highways, and urban and suburban roadways. In addition, warrants for bypass lanes were developed for rural two-lane highways. A "Design Guide on Left-Turn Accommodations at Unsignalized Intersections" was developed that discusses left-turn lane designs, traffic control treatments, and case study examples.
Book Synopsis Capacity and Operational Effects of Midblock Left-turn Lanes by : James A. Bonneson
Download or read book Capacity and Operational Effects of Midblock Left-turn Lanes written by James A. Bonneson and published by Transportation Research Board. This book was released on 1997 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Development of Guidelines for Triple Left and Dual Right-turn Lanes by :
Download or read book Development of Guidelines for Triple Left and Dual Right-turn Lanes written by and published by . This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Left- or right-turn lanes at intersections improve safety and operations by separating turning and through vehicles. At intersections with heavy turning demand, it may be necessary to provide multiple turn lanes. Triple left-turn (TLT) and dual right-turn (DRT) lanes are still considered as relatively new designs that many agencies are reluctant to use, so they are somewhat limited in Texas. Guidelines for TLT or DRT lanes are almost nonexistent, leaving traffic engineers to rely on judgment for their designs. Therefore, their research was needed to develop consistence guidance. The 0-6112 project achieved two primary project goals: (1) development of geometric and signal design guidelines for TLT and DRT lanes; and (2) evaluation of the safety and operational performance of TLT and DRT sites in Texas. Researchers conducted field studies at 5 TLT and 20 DRT, primarily in the Dallas-Fort Worth and Houston urban areas, in order to evaluate lane utilization patterns, saturation flow rates, conflicts, and other operational factors. The research team also analyzed safety performance by investigating the crash history of the 25 sites using three techniques: collision diagrams, field conflict study, and comparison study. The results revealed that TLT lanes do not experience any major safety issues and also concluded that, in general, a well-designed DRT lane does not cause significantly higher crash frequency or severity compared to single right-turn lanes. Based on the results of this research and the geometric and signal design guidelines, Tudor and other agencies should be confident that well-designed TLT and DRT lanes can be implemented to address heavy turning demand at key intersections. The evaluation of these multiple turn lane sites in Texas revealed that they perform well from both operational and safety standpoints. TLT and DRT lanes are not appropriate for all situations, and their use should be supported by an operational analysis. Other techniques (grade separation, signal timing, etc.) might be better solutions for a particular site, especially when considering the effects of adjacent intersections, pedestrian/bicycle movements, and other key factors. Researchers developed a product, Keys to Successful Public Outreach, which is useful for implementing multiple turn lane projects.
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.
Book Synopsis Development of Warrants for Left-turn Lanes by : Kenneth R. Agent
Download or read book Development of Warrants for Left-turn Lanes written by Kenneth R. Agent and published by . This book was released on 1979 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Development, Evaluation and Application of Left Turn Signal Warrants by : Jonathan Upchurch
Download or read book Development, Evaluation and Application of Left Turn Signal Warrants written by Jonathan Upchurch and published by . This book was released on 1991 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study dealt with five types of left turn signal phasing: permissive, leading exclusive, lagging exclusive, leading exclusive/permissive, and lagging exclusive/permissive. The objectives of this research project were to: (1) develop a research work plan to conduct a statistically valid study for the development of numerical warrants for left turn movements; and (2) prepare a database of available information on signalized intersections and select the intersections to be used in the future study. This report describes the database of Arizona signalized intersections created in this project, the findings on left turn accident rates for different types of left turn phasing (using a nonrandom sample), and results of a validation study of the TEXAS computer simulation model. It also presents a research work plan for a future research project.
Book Synopsis Evaluation of Sign and Marking Alternatives for Displaced Left-turn Lane Intersections by :
Download or read book Evaluation of Sign and Marking Alternatives for Displaced Left-turn Lane Intersections written by and published by . This book was released on 2009 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: This document describes research conducted by the Federal Highway Administration (FHWA) to support guidance on the signing and marking of displaced left turn lane intersections (DLT) also known as continuous flow intersections (CFI). The DLT is an at grade intersection that is intended to support high traffic flow where there is a large volume of left turns and heavy through volumes. Its design permits the use of two or three phase traffic signals at the junction of two roads, while still providing at grade protected left turn movements.
Book Synopsis Guidelines for Use of Left-turn Lanes and Signal Phases by : H. J. Lin
Download or read book Guidelines for Use of Left-turn Lanes and Signal Phases written by H. J. Lin and published by . This book was released on 1984 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Triple Left-turn Lanes at Signalized Intersections by :
Download or read book Triple Left-turn Lanes at Signalized Intersections written by and published by . This book was released on 2002 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Development of Pedestrian Safety Based Warrants for Permissive Left-turn Control by : Qi Yi (Ph.D.)
Download or read book Development of Pedestrian Safety Based Warrants for Permissive Left-turn Control written by Qi Yi (Ph.D.) and published by . This book was released on 2010 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Guidelines for Exclusive/permissive Left-turn Signal Phasing by : Benjamin H. Cottrell
Download or read book Guidelines for Exclusive/permissive Left-turn Signal Phasing written by Benjamin H. Cottrell and published by . This book was released on 1985 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this research was to develop guidelines for the use of exclusive/permissive left-turn signal phasing. This was achieved by collecting data on traffic and roadway conditions for exclusive, exclusive/permissive, and permissive left-turn phasings and then analyzing the data to identify relationships between the left-turn phasings and traffic and roadway conditions. The guidelines addressed the following" (1) volume guidelines based on peak hour minimum left-turn volume and the product of the peak- hour left-turn and opposing volumes, (2) annual left-turn accident experience, (3) left-turn traffic conflict experience based on critical number and rates, (4) left-turn delay, and (5) site condition factors identified in the study
