Ramp Metering Algorithms And Approaches For Texas

Ramp Metering Algorithms and Approaches for Texas

The primary objective of this project was to compare ramp metering algorithms and develop guidelines for improving ramp metering operations in Texas. As part of this research project, researchers collected data at several sites in Houston, Texas. Data analysis showed that many congested freeways are facing heavy ramp demand, and require significant changes in existing ramp metering operations if ramp metering continues to be used as part of freeway traffic management. Furthermore, researchers used computer simulation to compare the effectiveness of ALINEA with queue flush with the existing strategy of metering at the maximum rate with queue flushing. Researchers found that ALINEA does not provide any benefits when queue flushing is permitted. Under heavy demand conditions such as those in Houston, the current strategy to meter at the fastest rate remains the most beneficial. However, this strategy also provides limited benefits. Finally, researchers developed guidelines and recommendations for current and future ramp metering operations in Texas. This report documents the research results.

Optimization in Civil & Environmental Engineering

Advanced Freeway System Ramp Metering Strategies for Texas

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.