Kate Lyman, Portland State University Travel Time Reliability in Regional Transportation Planning 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. The study concludes by providing recommendations to MPOs for ways to incorporate travel time reliability measures into regional transportation planning. Recommendations MPOs can incorporate travel time reliability into their RTPs in the following ways: 1.State the improvement and maintenance of travel time reliability as a systemwide goal. 2.Evaluate existing transportation system using measures of travel time reliability. 3.Use results of the analysis to prioritize improvements into the transportation system that will improve reliability. Objectives 1.Analyze regional transportation plans for usage of travel time reliability 2.Analyze freeway segments in Portland, Oregon to provide a case study of how to incorporate travel time reliability into regional transportation planning 3.Provide recommendations to MPOs on how to utilize travel time reliability Acknowledgements Dr. Jennifer Dill and Dr. Robert Bertini provided invaluable support and input into this research. Dr. Kristin Tufte was instrumental in gaining the necessary data from the PORTAL data archive. DailyPM Peak (4-6 PM)AM Peak (7-9 AM)Rating I-5 NORTH %68%33% Average %68%36% %68%45% %63%42% Average24%67%39% I-5 SOUTH %68%46% Average %60%34% %75%34% %64%37% Average23%67%38% I-205 NORTH %60%17% Good %58%28% %65%36% %57%40% Average17%60%30% I-205 SOUTH %66%34% Good %54%50% %59%47% %44%43% Average18%56%43% I-405 SOUTH %101%21% Poor %136%19% %133%21% %130%23% Average27%125%21% I-84 EAST %85%7% Average %77%9% %77%11% %82%20% Average24%80%12% I-84 WEST %55%86% Very Poor %47%84% %56%89% %111%74% Average37%67%83% HWY 217 NORTH %41%31% Good %49%42% %58%53% %50%47% Average20%49%43% HWY 217 SOUTH %94%58% Poor %97%46% %100%48% %97%46% Average28%97%50% HWY 26 EAST %96%73% Very Poor %75%73% %89%67% %70%83% Average34%83%74% HWY 26 WEST %50%42% Poor %45%59% %44%18% %44%37% Average23%46%39% Table 1: Buffer Indices on Freeways in Portland, Oregon MPOs Studied Baltimore Metropolitan Council, Bonneville Metropolitan Planning Organization, Chittenden County Metropolitan Planning Organization, Durham-Chapel Hill-Carrboro Metropolitan Planning Organization, Houston-Galveston Area Council, Indian Nations Council of Governments, Madison Area Metropolitan Planning Organization, Maricopa Association of Governments, Metro, Metroplan Orlando, Metropolitan Council, Mid-Ohio Regional Planning Council, Mid-Region Council of Governments, Montgomery Area Metropolitan Planning Organization, Nashville Area Metropolitan Planning Organization, New York Metropolitan Transportation Council, North Central Texas Council of Governments, Regional Transportation Council of Southwest Washington, San Diego Association of Governments, Tri-County Regional Planning Commission. Case Study of Portland Freeways Conclusions Travel time reliability not used as a congestion measure Travel time reliability sometimes stated as goal or policy of the system Travel time reliability sometimes stated as a performance measure for one mode (e.g. transit service reliability) Content Analysis of Regional Transportation Plans Figure 2: I-84 West Buffer Index Figure 1: I-405 South Buffer Index (95% travel time – average travel time) average travel time Buffer Index: Prioritize I-405 South and Hwy 217 South in the PM Peak Prioritize I-84 West and Hwy 26 East in the AM Peak Worst daily reliability: I-84 West, Hwy 26 East, Hwy 217 South Figure 3: Hwy 217 South Buffer Index Figure 4: Hwy 26 East Buffer Index