Examining Route Diversion And Multiple Ramp Metering Strategies For Reducing Real Time Crash Risk On Urban Freeways
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Examining Route Diversion And Multiple Ramp Metering Strategies For Reducing Real Time Crash Risk On Urban Freeways
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Author : Vikash V. Gayah
language : en
Publisher:
Release Date : 2006
Examining Route Diversion And Multiple Ramp Metering Strategies For Reducing Real Time Crash Risk On Urban Freeways written by Vikash V. Gayah and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with categories.
It should also be noted that both route diversion and ramp metering were found to increase the overall network travel time. However, the best route diversion and ramp metering strategies were selected to ensure that the operational capabilities of the network were not sacrificed in order to increase the safety along the freeway. This was done by setting the maximum allowable travel time increase at 5% for any of the ITS strategies considered.
Exploring The Potential Of Combining Ramp Metering And Variable Speed Limit Strategies For Alleviating Real Time Crash Risk On Urban Freeways
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Author : Kirolos Maged Haleem
language : en
Publisher:
Release Date : 2007
Exploring The Potential Of Combining Ramp Metering And Variable Speed Limit Strategies For Alleviating Real Time Crash Risk On Urban Freeways written by Kirolos Maged Haleem and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with categories.
In summary, Ramp Metering was more beneficial at congested situations, while Variable Speed Limits were more beneficial at free-flow conditions. At conditions approaching congestion, the combination of Ramp Metering and Variable Speed Limits produced the best benefits. These results illustrate the significant potential of ITS strategies to improve the safety and efficiency of urban freeways.
Evaluating Ramp Metering And Variable Speed Limits To Reduce Crash Potential On Congested Freeways Using Micro Simulation
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Author : Albinder Singh Dhindsa
language : en
Publisher:
Release Date : 2005
Evaluating Ramp Metering And Variable Speed Limits To Reduce Crash Potential On Congested Freeways Using Micro Simulation written by Albinder Singh Dhindsa and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with Adaptive control systems categories.
Recent research at UCF into defining surrogate measures for identifying crash prone conditions on freeways has led to the introduction of several statistical models which can flag such conditions with a good degree of accuracy. Outputs from these models have the potential to be used as real-time safety measures on freeways. They may also act as the basis for the evaluation of several intervention strategies that might help in the mitigation of risk of crashes.
Examining Dynamic Variable Speed Limit Strategies For The Reduction Of Real Time Crash Risk On Freeways
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Author : Ryan J. Cunningham
language : en
Publisher:
Release Date : 2007
Examining Dynamic Variable Speed Limit Strategies For The Reduction Of Real Time Crash Risk On Freeways written by Ryan J. Cunningham and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with Intelligent transportation systems categories.
In the free-flow condition (60% loading), the best treatments involved the more liberal threshold for defining homogeneous speed zones (5 mph) and the more liberal implementation distance (entire speed zone), as well as a minimum time period of 10 minutes. This treatment was actually shown to significantly reduce the network travel time by 0.8%. It was also shown that this particular implementation strategy (lowering upstream, raising downstream) is wholly resistant to the effects of crash migration in the 60% loading scenario. In the condition approaching congestion (80% loading), the best treatment again involved the more liberal threshold for homogeneous speed zones (5 mph), yet the more conservative implementation distance (half the speed zone), along with a minimum time period of 5 minutes. This particular treatment arose as the best due to its unique capability to resist the increasing effects of crash migration in the 80% loading scenario. It was shown that the treatments implementing over half the speed zone were more robust against crash migration than other treatments. The best treatment exemplified the greatest benefit in reduced sections and the greatest resistance to crash migration in other sections. In the 80% loading scenario, the best treatment increased the network travel time by less than 0.4%, which is deemed acceptable. No treatment was found to successfully reduce the rear-end and lane-change crash risks in the congested traffic condition (90% loading). This is attributed to the fact that, in the congested state, the speed of vehicles is subject to the surrounding traffic conditions and not to the posted speed limit. Therefore, changing the posted speed limit does not affect the speed of vehicles in a desirable manner. These conclusions agree with Dilmore (2005).
Advanced Freeway System Ramp Metering Strategies For Texas
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Author : Carroll J. Messer
language : en
Publisher:
Release Date : 1993
Advanced Freeway System Ramp Metering Strategies For Texas written by Carroll J. Messer and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1993 with Electronic traffic controls categories.
Freeway ramp metering systems have been used to improve urban freeway flow. However, control strategies must be properly adjusted to account for ramp queues overflowing onto surface streets and provide equitable on-ramp control during various operating periods. An improved solution can be obtained by optimizing this problem simultaneously for a group of time slices. This study identifies and examines a microcomputer-based optimization scheme that can assist in developing efficient freeway control strategies for on-line freeway surveillance and control. A multi-level freeway control structure is employed for which ramp metering control algorithms are developed for each level of control. Flow-based and lane occupancy-based system algorithms are presented. Detailed data file requirements are provided for each control level. A microcomputer prototype, or laboratory test version of the system level, will be described in a companion project report.
Simulation Based Integrated Control Algorithm For Controlling Shockwave Propagation On Freeways And Queue Spillback At On Ramps
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Author : Karteek Kumar Allam
language : en
Publisher:
Release Date : 2015
Simulation Based Integrated Control Algorithm For Controlling Shockwave Propagation On Freeways And Queue Spillback At On Ramps written by Karteek Kumar Allam and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
Heavy traffic flow entering the freeway mainline can cause or worsen congestion on the freeway mainline due to interrupted on-ramp traffic. In order to address this problem, Freeway ramp metering systems are usually deployed to improve the traffic flow on urban freeways. These systems are attended to improve the flow on the freeway by regulating the on-ramp rate entering the freeway. However, amongst all the possible factors contributing to traffic congestion on freeways and arterials connected via ramps, lack of coordination in the operation of various system components is a major source of inefficiency at freeway and ramp conjunctions. Various ramp metering algorithms have been developed in an attempt to solve the unsystematic problem in coordinating the control of freeway, and arterials. Nevertheless, most of the algorithms control actions were selected based on either pre-defined plans or detected traffic condition. Implementation of the algorithms on the field is also a concern because of its excessive data requirements of these algorithms. Furthermore, existence of a range of flow rates in synchronized flow traffic can cause breakdown due to internal perturbations. Many algorithms failed to address the issue of worsening freeway congestion due to upstream traffic at the on-ramp. This research will formulate an integrated ramp metering control algorithm, using real time traffic measurements. Multiple priority objectives are explicitly set up to delay the congestion due to internal perturbations, maintain the throughput of freeway, and to prevent on-ramp vehicles from overflowing into arterials. This algorithm is also formulated to minimize the delays and control the shockwave propagation from the merge location of the on-ramp and the freeway. In order to measure the effectiveness, the proposed algorithm is compared with a traffic responsive algorithm, such as ALINEA (Asservissement LINeaire d'Entree Autoroutiere), and proposed recommendations accordingly. Considering the importance of gap acceptance and internal perturbations in the current research, calibration of the simulation model was conducted. For this purpose, video data was collected capturing the traffic at the merge location of the freeway and on-ramp, from which the accepted gaps and headways of the vehicles merging into the freeway have been extracted. This was given as an input to the VISSIM simulation model for calibration. The simulation test results indicate that the proposed integrated ramp metering algorithm is more effective than the ALINEA and Fixed Time ramp metering algorithms in terms of reducing the system delays and travel time on the freeway, and minimizing the freeway breakdown. Additionally, the proposed algorithm works efficiently at the ramp traffic flow of no more than 580 veh/hr. In other words, the ALINEA likely outperforms the proposed algorithm as the ramp traffic exceeds 580 veh/hr. The contribution of the research will be reflective of the following aspects: 1) developing a method with a supportive algorithm for minimizing the shockwave propagation by dampening shockwave formation of mainline freeway traffic; 2) developing a method with a supportive algorithm to reduce mainline freeway shockwaves by dispatching vehicles from the on-ramp at a flow rate that can best fit in the observed gaps to be available from the freeway traffic; 3) identifying the minimum accepted gaps at the merge location from video observation to develop appropriate gap acceptance parameters; and 4) developing an integrated computing system to provide a fundamental platform for further functionality expansion in the future for study of a multiple-ramp situation at a freeway system.
Control Strategies In Response To Freeway Incidents
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Author :
language : en
Publisher:
Release Date : 1981
Control Strategies In Response To Freeway Incidents written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1981 with Disabled vehicles on express highways categories.
Evaluation Of Ramp Metering Strategies At Local On Ramps And Freeway To Freeway Interchanges Using Computer Simulation Modelling Approach
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Author : Abdul-Rahman Ibrahim Hamad
language : en
Publisher:
Release Date : 1987
Evaluation Of Ramp Metering Strategies At Local On Ramps And Freeway To Freeway Interchanges Using Computer Simulation Modelling Approach written by Abdul-Rahman Ibrahim Hamad and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1987 with Express highways categories.
A Microsimulation Analysis Of The Mobility Impacts Of Intersection Ramp Metering
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Author : William Jared Wall
language : en
Publisher:
Release Date : 2013
A Microsimulation Analysis Of The Mobility Impacts Of Intersection Ramp Metering written by William Jared Wall and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.
Urban freeway demand that frequently exceeds capacity has caused many agencies to consider many options to reduce congestion. A series of solutions that falls under the Active Traffic Management (ATM) banner have shown promising potential. Perhaps the most popular ATM strategy is ramp metering. Ramp metering involves limiting the access of vehicles to freeways at an entrance ramp. By doing this, freeway throughput, speeds, and travel time reliability can be increased, while the number of traffic incidents can be decreased. This study examines the application of an innovative ramp metering strategy, Intersection Ramp Metering (IRM), at a section of Loop 1 in Austin, TX. IRM implements the ramp metering function at the intersection immediately upstream of the entrance ramp, rather than on the ramp itself. A microsimulation analysis of this application is performed in VISSIM, and the results confirm that freeway throughput (+10%), and system average travel time (-14%), can be improved, as well as several other performance measures.
Integrated Real Time Freeway On Ramp Control Strategies
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Author : Menahem Eldor
language : en
Publisher:
Release Date : 1976
Integrated Real Time Freeway On Ramp Control Strategies written by Menahem Eldor and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1976 with Electronic traffic controls categories.