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Mathematical Problems in Engineering
Volume 2013 (2013), Article ID 504579, 9 pages
Research Article

Empirical Study of Travel Time Estimation and Reliability

1Department of Civil Engineering, Institute of Transportation Engineering, Tsinghua University, Beijing 100084, China
2Department of Civil and Environmental Engineering, University of California, Davis, CA 95616, USA

Received 25 August 2013; Accepted 24 October 2013

Academic Editor: Wuhong Wang

Copyright © 2013 Ruimin Li et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


This paper explores the travel time distribution of different types of urban roads, the link and path average travel time, and variance estimation methods by analyzing the large-scale travel time dataset detected from automatic number plate readers installed throughout Beijing. The results show that the best-fitting travel time distribution for different road links in 15 min time intervals differs for different traffic congestion levels. The average travel time for all links on all days can be estimated with acceptable precision by using normal distribution. However, this distribution is not suitable to estimate travel time variance under some types of traffic conditions. Path travel time can be estimated with high precision by summing the travel time of the links that constitute the path. In addition, the path travel time variance can be estimated by the travel time variance of the links, provided that the travel times on all the links along a given path are generated by statistically independent distributions. These findings can be used to develop and validate microscopic simulations or online travel time estimation and prediction systems.