Evaluation of the Mobility Impacts of Proposed Ramp Metering and Merge Control Systems
Evaluation of the Mobility Impacts of Proposed Ramp Metering and Merge Control Systems

Author: Michael DeGaspari

Publisher:

Published: 2012

Total Pages: 164

ISBN-13:

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Increasing demand on freeway facilities is a major challenge facing urban areas in the United States and throughout the world. Active Traffic Management (ATM) strategies can be used to increase the performance of these facilities through improved operations without the significant expenditure associated with adding capacity. One ATM strategy that has been widely deployed in the current state of practice is ramp metering, which controls the traffic demand placed on a freeway. Merge control strategies are less prevalent and largely undeveloped. This study examines the recurrently congested northbound section of Interstate Highway 35 that approaches downtown Austin, Texas. Using the VISSIM microsimulation platform, a model of this segment was developed and calibrated to reflect current peak-hour congestion. Within this model, ramp metering and merge control technologies were implemented. The impacts on traffic throughput, speed and travel time for each of these proposed systems are evaluated.

Evaluation of Mobility Impacts of Temporary Ramp Metering in Work Zones
Evaluation of Mobility Impacts of Temporary Ramp Metering in Work Zones

Author: Naghma Hassan

Publisher:

Published: 2012

Total Pages: 170

ISBN-13:

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Road maintenance has been growing in the United States and brings a variety of challenges to the transportation profession. Work zone congestion is one of the most important factors contributing to the delay and safety of freeways. Many control methodologies have been applied to work zones in order to reduce freeway congestion and delay. One means of control is ramp metering, which has been deployed since 1963 in the United States and has proven to be successful. This thesis' objective is to evaluate and simulate the effect of ramp metering on freeway work zones; traffic performance measures such as delay, speed, and number of stops are used for the evaluation. A literature review showed that a main factor contributing to the freeway work zone delay is a high percentage of commercial trucks. Due to the role of truck percentage in work zone performance, effectiveness of ramp metering in work zone control is evaluated with different truck percentages. The lane configuration for all the studied sites work zones was 2 lanes to 1 lane, because it's frequency in real-world applications. In the evaluation of ramp metering in work zones, the traffic volumes investigated were less than, equal to, and more than capacity (650vph, 1240vph, and 1854vph). Mainline (a link used for trough traffic) truck percentage and ramp truck percentage varied from 10% to 40%, and 10% to 20%, respectively. As a result, a total of 8 cases were created and simulated using VISSIM traffic simulation software.

Ramp Metering
Ramp Metering

Author: E. D. Arnold

Publisher:

Published: 1998

Total Pages: 32

ISBN-13:

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Ramp metering is an effective, viable, and practical strategy used to manage freeway traffic. It is a proven freeway management technique as various forms of ramp control have been in place since the 1960s in the Chicago, Detroit, and Los Angeles areas. Due in part to the success of these early applications, ramp metering has received increased emphasis in recent years under the umbrella of advanced traffic management systems (ATMS), a component of intelligent transportation systems (ITS). ITS America reports that there are currently more than 40 ATMS deployed, under construction, or in the planning stage in the U.S. by state transportation agencies. The future of ramp metering is also in this ITS context. Integration and interface with local street system control and other advanced ITS traffic control systems such as advanced vehicle control systems, dynamic route guidance, and advanced traveler information systems are the latest in ramp metering applications. Ramp meters are in place and working effectively on segments of I-395 and I-66 in Northern Virginia. The Virginia Department of Transportation is very much interested in the feasibility of implementing ramp metering on other segments of freeways throughout the state. Accordingly, the purpose of this study was to review and synthesize the existing literature on ramp metering. Specific topics included in the review were: impacts of ramp metering, including its advantages/benefits and disadvantages/disbenefits, warrants, criteria, and guidelines for ramp metering, metering rates. Detailed information on these topics is included in the report as well as general conclusions regarding ramp metering.

A Microsimulation Analysis of the Mobility Impacts of Intersection Ramp Metering
A Microsimulation Analysis of the Mobility Impacts of Intersection Ramp Metering

Author: William Jared Wall

Publisher:

Published: 2013

Total Pages: 184

ISBN-13:

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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.

Development and Evaluation of Selected Mobility Applications for VII
Development and Evaluation of Selected Mobility Applications for VII

Author: Steven E. Shladover

Publisher:

Published: 2011

Total Pages: 98

ISBN-13:

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"This report describes the development of two of the three mobility applications that PATH has developed and evaluated under the sponsorship of the FHWA Exploratory Advanced Research Program, with cost share funding provided by Caltrans Contract 65A0351. These applications are intended to use DSRC wireless communications among vehicles and between vehicles and the roadway infrastructure to improve mobility on limited-access highways. The first application combines ramp metering with variable speed limits to enhance control of traffic so that traffic flow breakdowns can be deferred or avoided at bottleneck locations. The second application uses vehicle-vehicle communication to improve the performance of adaptive cruise control systems so that they can operate safely with smaller longitudinal gaps and vehicle-roadside communication to provide adjustments to their set speed and gap settings to adapt to changes in local traffic conditions."--Abstract, p. i.

Evaluation of Temporary Ramp Metering for Work Zone Safety
Evaluation of Temporary Ramp Metering for Work Zone Safety

Author: Zhongyuan Zhu

Publisher:

Published: 2012

Total Pages: 68

ISBN-13:

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Ramp metering has been successfully implemented in many states and studies have documented its positive mobility and safety benefits. However, there have been no studies on the use of ramp metering for work zones. This thesis reports the results from the first deployment of temporary ramp meters in work zones in the United States. Temporary ramp meters were deployed at seven work zones in Missouri. Due to lack of crash data, this study uses video data to extract alternative safety measures such as driver compliance, merging behavior, speed differentials, lane changing, and braking maneuvers. This evaluation suggests that temporary ramp meters should only be deployed at work zone locations where there is potential for congestion and turned on only during periods of high congestion. In comparison to over 90% compliance rates of permanent ramp meters implemented in other states, field data showed compliance rates from 40.5% to 82.9% in temporary ramp meter. This suggested that non-compliance could be a major safety issue in the deployment of temporary ramp meters. The use of a three-section instead of a traditional two-section signal head used for ramp metering produced significantly higher compliance rates. This thesis then aggregated the data into groups to further analyze the effects of different factors such as platoons, commercial trucks, work zone type and work zone-ramp configuration. After analyzing general characteristics of mainline and ramp vehicle speed and speed differentials, this study then focused on findings for different comparison groups. The two comparison groups are "between two work zones" versus "before work zone" configuration and "left-lane closed" versus "right-lane closed" work zone type. Results indicated lower mean speeds of mainline and ramp vehicles and higher differentials when ramp metering was turned on. This is expected and again temporary ramp meters are recommended only where congestion occurs. Congestion will lead to lower mainline speeds thus lower speed differentials either with or without ramp metering. Finally, analysis of merging headways showed that temporary ramp meters were effective in separating platoons before vehicles merged into mainline. This produces more single-vehicle merging which requires shorter gaps and causes fewer impacts on the mainline traffic.