Travel Time Reliability Estimation: Use of Median Travel Time as Measure of Central Tendency

This paper proposes use of median travel time compared to mean travel time as the measure of central tendency to calculate Buffer Time Index (BTI), one of the most important measures of travel time reliability. This study examined gamma, exponential, largest extreme value, smallest extreme value, logistic, Weibull, lognormal and log-logistic distributions to determine the best fit to travel time data for two cases: 24 hours and peak hours for a highway with Variable Speed Limit (VSL) conditions. The goodness-of-fit tests indicated that the log-normal distribution best represented the travel time data for peak periods and log-logistic distribution better fitted the travel time data for 24 hours. The log-logistic distribution and log-normal distributions were positively skewed and for skewed distributions, median is the best estimate of central tendency. Hence, median travel time is proposed for calculating BTI. The difference in values of BTIs were evaluated when mean and median travel time were used. Travelers must add extra time to their average travel time to ensure on-time arrival. It was found that this extra time increases from 11% to 30% when median travel time is used as the average travel time compared to mean travel time for calculation of BTI.

• Record URL:
  https://doi.org/10.1061/41167(398)7
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/isbn/9780784411674
• Supplemental Notes:
  • Copyright © 2011 ASCE
• Corporate Authors:

  American Society of Civil Engineers

  1801 Alexander Bell Drive
  Reston, VA  United States  20191-4400
• Authors:
  • Arezoumandi, M
  • Bham, G. H.
• Conference:
  • First Congress of Transportation and Development Institute (TDI)
  • Location: Chicago IL, United States
  • Date: 2011-3-13 to 2011-3-16
• Publication Date: 2011

Language

• English

Media Info

• Media Type: Digital/other
• Monograph Title: Transportation and Development Institute Congress 2011 : Integrated Transportation and Development for a Better Tomorrow

Subject/Index Terms

• TRT Terms: Logistics; Peak periods; Reliability (Statistics); Speed limits; Traffic estimation; Traffic flow; Travel time; Variable speed limits
• Subject Areas: Data and Information Technology; Highways; Operations and Traffic Management; I72: Traffic and Transport Planning;

Filing Info

• Accession Number: 01347248
• Record Type: Publication
• ISBN: 9780784411674
• Files: TRIS, ASCE
• Created Date: Aug 8 2011 2:10PM