Traffic Operations and Safety Benefits of Active Traffic Strategies on TxDOT Freeways.

摘要

Traffic congestion is an increasing problem in the nations urban areas, leading to personal inconvenience, increased pollution, hampered economic productivity, and reduced quality of life. While traffic congestion tends to continuously increase, growth in transportation infrastructure is limited by financial and land availability constraints. This has placed an increasing emphasis on using active traffic management strategies (ATM), such as speed harmonization, peak-period shoulder use, and ramp metering, to efficiently manage congestion using existing freeway capacity. Safety implication of these strategies is of prime concern before they can be implemented on the ground. This project developed a series of interdependent models and a simulation framework to evaluate the traffic operations and safety benefits of ATM strategies. Four ATM scenarios were evaluated in this study: variable speed limits (VSL), peak-period shoulder use, VSL and shoulder use, and ramp metering. Overall these ATM strategies were found to homogenize traffic and create safer driving conditions, but did not increase the throughput of the freeway. The study calls for caution and comprehensive evaluation in the case of shoulder use as sudden one-lane drop at the end of the shoulder-use section may have adverse effect on traffic operations and safety. The ITS devices required to implement these strategies, enforcement issues, potential impediments in their implementations, and a framework for cost-benefit analysis to determine the economic viability are also discussed.