Student Researcher: Meead Saberi K.

Faculty Advisor: Robert L. Bertini

ABSTRACT: Travel time based performance measures are widely used for transportation systems and particularly freeways. However, it has become evident that travel time reliability, taking into account the variability in travel times, may be a more important metric for evaluating the performance of a freeway over time and space. The objective of this study is to build upon previous work performed at the directional corridor level for planning purposes and analyze the ways in which travel time reliability can be measured at the segment level, aimed at operational solutions and hotspot identification. This was accomplished using archived loop detector data from the Interstate 5 freeway in Portland, Oregon as a case study. Breaking the overall 24-mile northbound I-5 freeway corridor into shorter segments on the order of one mile long, this study shows how reliability can vary across freeway segments (space) and over time. Corridor travel time variance of correlated segments versus uncorrelated segments is also discussed. To explore the inconsistency among existing commonly used travel time reliability indicators, several reliability measures are examined using differential reliability maps and compared with travel time based measures. Finally several reliability measures are used to prioritize freeway segments according to travel time reliability which is beneficial in regional transportation planning, operations, and bottleneck prioritization.

PRODUCTS:

conferenceproceedings Saberi, M. and R.L. Bertini, "Beyond Corridor Reliability Measures: Analysis of Freeway Travel Time Reliability at the Segment Level for Hotspot Identification." Proceedings of the 89th Annual Meeting of the Transportation Research Board, Washington, D.C.

presentation Saberi, M. and R.L. Bertini, "Segment Level Analysis of Travel Time Reliability." Compendium of Technical Papers, Institute of Transportation Engineers, District 6 Annual Meeting, Denver, Colorado, July 12