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Author: Sarang S. Ranade Publisher: ISBN: Category : Languages : en Pages : 238
Book Description
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.
Author: Sarang S. Ranade Publisher: ISBN: Category : Languages : en Pages : 238
Book Description
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.
Author: Yi Qi Publisher: ISBN: Category : Right-turn lanes Languages : en Pages : 126
Book Description
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.
Author: Publisher: ISBN: Category : Left-turn lanes Languages : en Pages : 80
Book Description
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.
Author: Lee Rodegerdts Publisher: Transportation Research Board ISBN: 0309098742 Category : Roads Languages : en Pages : 125
Book Description
"Research sponsored by the American Association of State Highway and Transporation Officials in cooperation with the Federal Highway Administration."
Author: Sarang S. Ranade
Author: Sarang S. Ranade
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Author: Yi Qi
Author: M. D. Harmelink
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Author: 
Author: Lee Rodegerdts
Author: Kenneth R. Agent
Author: Kenneth R. Agent
Author: