Estimating Path Travel-Time Reliability
The estimation of path or trip travel-time reliability is critical to any Advanced Traveler Information System. The state-of-practice procedures for estimating path travel-time reliability assume that travel times follow a normal distribution and require a measure of trip travel-time variance. The study analyzes AVI data from San Antonio and demonstrates through goodness-of-fit tests that the assumption of normality is, from a theoretical standpoint, inconsistent with field travel-time observations and that a lognormal distribution is more representative of roadway travel times. However, visual inspection of the data demonstrates that the normality assumption may be sufficient from a practical standpoint given its computational simplicity. The paper then proposes five methods for the estimation of path travel-time variance from its component segment travel-time variances. The analysis demonstrates that computing the trip travel-time coefficient of variation as the conditional expectation over all realizations of roadway segments provides estimates within 13% of field observations for both uncongested and congested conditions.
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Corporate Authors:
500 Fifth Street, NW
Washington, DC United States 20001 -
Authors:
- Rakha, Hesham Ahmed
- El-Shawarby, Ihab
- Arafeh, Mazen
- Dion, Francois
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Conference:
- Transportation Research Board 86th Annual Meeting
- Location: Washington DC, United States
- Date: 2007-1-21 to 2007-1-25
- Date: 2007
Language
- English
Media Info
- Media Type: CD-ROM
- Features: Figures; References; Tables;
- Pagination: 15p
- Monograph Title: TRB 86th Annual Meeting Compendium of Papers CD-ROM
Subject/Index Terms
- TRT Terms: Advanced traveler information systems; Analysis of variance; Automatic vehicle identification; Highway operations; Reliability; State of the practice; Traffic; Traffic congestion; Traffic data; Traffic flow; Transportation planning; Travel time
- Geographic Terms: San Antonio (Texas)
- Subject Areas: Data and Information Technology; Highways; Operations and Traffic Management; Planning and Forecasting; I72: Traffic and Transport Planning;
Filing Info
- Accession Number: 01047317
- Record Type: Publication
- Report/Paper Numbers: 07-0488
- Files: TRIS, TRB
- Created Date: Feb 8 2007 5:04PM