Paper Details

TRB 91st Annual Meeting (January 22-26, 2012)

Event Number:	493
Event Title:	Research in Traffic Flow Theory and Characteristics, Part 4 (Part 1, Session 403; Part 2, Session 433; Part 4, Session 493)
Event Date:	Jan 24 2012 8:30AM- 10:15AM
Event Location:	Marriott, Salon 2
Event Description:
Event Agenda:

Time-Variant Travel Time Distributions and Reliability Metrics and Their Utility in Reliability Assessments (12-3089)

There are several metrics of reliability that have been recommended for use. These metrics may need to be calculated at relatively fine levels of aggregation of travel time data when used for advanced management strategies and transportation system modeling and analysis. This study investigates the variation of travel time distributions by time of day at fine temporal aggregation levels, the sensitivity of various reliability metrics to these variations, the effect of the aggregation level choices on the calculated metrics, and the amount of data required to estimate stable values of the reliability metrics. The investigation is made for a facility that has a general purpose (GP) lanes and high-occupancy toll (HOT) lanes. The results show that the parameters of travel time distributions vary during the peak period reflecting the effects of the traffic congestion, traffic flow dynamics, and the proportion of the contribution of non-recurrent factors such as incidents to the unreliability of travel time on the investigated facility. Different trends of variations are observed when using different reliability metrics to assess reliability as the congestion level changes during the peak period. The results also show that examining combinations of time-variant static distribution parameters and reliability metrics of the GP and HOT lanes can provide valuable information that cannot be obtained when performing the analysis at higher aggregation levels. Based on the results of the study, at least one year of data is recommended for use to obtain stable values of reliability metrics.

Authors
     Alvarez, Patricio Alejandro, Florida International University
     Hadi, Mohammed , Florida International University