Student Researcher: Kate Lyman, MURP

Faculty Advisor: R.L. Bertini

ABSTRACT: Travel time reliability is an important measure of congestion and can serve as baseline for prioritizing improvements into a region's transportation system. This paper begins with a literature review of travel time reliability and its value as a congestion measure. It then presents the methodology and results of a content analysis of twenty regional transportation plans from across the nation. This analysis concludes that travel time reliability is not currently used as a congestion measure, and that the most common measures of congestion were the volume-to-capacity ratio, vehicle hours of delay, and average speed. The paper then uses data from Portland, Oregon to provide a case study for how to prioritize roadways according to travel time reliability measures. Conclusions from the case study were that I-84 West should be prioritized in the AM peak, and that I-405 South should be prioritized in the PM peak. This paper ends by recommending to metropolitan planning organizations that they use travel time reliability in the following ways: 1) incorporate it as a system-wide goal; 2) evaluate roadway segments according to travel time reliability measures; and 3) prioritize roadway segments using those measures.

PRODUCTS:

journal Lyman, K. and R. Bertini, "Using Travel Time Reliability Measures to Improve Regional Transportation Planning and Operations." Transportation Research Record: Journal of the Transportation Research Board, Transportation Research Board of the National Academies, Washington, D.C., 2008.

thesis Lyman, K., "Travel Time Reliability in Regional Transportation Planning." Field Area Paper, Nohad A. Toulan School of Urban Studies and Planning, Master of Urban and Regional Planning Program, June 2007

presentation Bertini, R. L. and K. Lyman, "Developing Improved Travel Time Reliability Measures for Real-Time and Archived ITS Data Applications." ITS Europe, Aalborg, Denmark, June 2007

conferenceproceedings Bertini, R.L. and K. Lyman, "Developing Improved Travel Time Reliability Measures for Real-Time and Archived ITS Data Applications." ITS Europe, Aalborg, Denmark, June 2007

presentation Lyman, K., "Travel Time Reliability." Presented at the Center for Transportation Studies Seminar, Portland State University, June 1, 2007 Streaming Video