TxDOT Research Library - TxDOT Research Project

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Investigating Regional Dynamic Traffic Assignment Modeling for Improved Bottleneck Analysis

What Was the Need?

Bottleneck mitigation is a classic transportation problem. In fact, many congestion issues that impact Texas drivers daily can be traced back to a bottleneck, be it stationary or moving. Further, the causes of bottlenecks can be complex and if one is al1eviated, one or more unexpected bottlenecks can quickly emerge elsewhere. Traditional transportation modeling approaches that may be applied for the examination of bottlenecks can typically be categorized as planning or operational in nature. Unfortunately, either approach is ill-suited for a comprehensive treatment of bottlenecks. Operational models lack the regional scope and travel behavior capabilities (e.g., route choice) necessary to holistically treat bottleneck mitigation's unexpected consequences. Moreover, planning models lack the precise representation of traffic needed to capture the intricacies of vehicular dynamics.

What's the Solution?

The Texas Department of Transportation (TxDOT) made geometric changes to the MoPac Expressway near the downtown Austin area in September 2010 to alleviate the existing bottleneck and improve travel conditions for downtown commuters during peak periods. This research study successfully employed dynamic traffic assignment modeling for bottleneck analysis at a regional scale and proved the feasibility of such an approach. To the best knowledge of the researchers this is the first instance of DTA application for a comprehensive bottleneck analysis. DTA modeling is gaining acceptance among transportation agencies due to its superior representation of time-varying travel condition compared to static traffic assignment. The next logical step in the evolution of this trend is to incorporate DTA into the traditional four-step transportation planning process. The research team provided a guiding framework to incorporate DTA into the planning process.

Project Number

0-6657

Status

Completed

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