Loading...

Estimating Traffic Flow in Urban Networks with Day-To-Day Travel Time Fluctuations

Torkjazi, Mohammad | 2011

542 Viewed
  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43071 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Poorzahedy, Hossain
  7. Abstract:
  8. Variations in supply and demand of transportation, as well as those in the related environment, would cause daily variations in user travel time of transportation networks. This phenomenon particularly happen in morning travel time peaks, and make estimation of travel time highly unreliable. Morning peak passengers, whose timely presence at the destinations are highly important to them, prefer to choose paths that have minimum travel time and maximum reliability. Thus, the look at travel time pessimistically, and based on their experience, they put a margin of reliability to reach at timely at their destinations.
    This study analysis such reliability margins based on the standard deviations of travel times. To this end, the travel times of many links in several selected paths of the network of the city of Tehran are measured in morning peak hours in 26 days. The standard deviations of the link travel times are estimated by the help of two models, one deterministic, and one probabilistic based on Copula. Two models of network equilibrium flow have been made to investigate which criterion are used by the users of the network to choose path in the morning peaks: mean travel time or pessimistic travel time which includes travel time variation measure. These models are applied to the networks of the city of Mashhad and Shiraz, which large metropolitan cities in Iran. The estimated volumes of traffic are compared to respective observed volumes over the links of several screen lines in these two cities. These comparisons show that pessimistic network equilibrium flow would estimate the observed flows better. This is particularly true for longer trips, where the travel times are more prone fluctuations
  9. Keywords:
  10. Travel Time Standard Deviation ; Pessimistic Equilibrium Flow ; Reliability ; Travel Time ; UrbanTransport

 Digital Object List

 Bookmark

No TOC