Calibration of the bunched exponential distribution of arrival headways

Research output: Journal article publicationJournal articleAcademic researchpeer-review

52 Citations (Scopus)


The estimation of arrival headways is fundamental to the modelling of gap acceptance processes for estimating capacities of sign-controlled traffic streams, roundabout entry streams and filter turns at signalized intersections. It is also essential in modelling both vehicle-actuated signal timings and queueing at all types of intersections for performance prediction. This paper considers a class of arrival headway distributions known as negative exponential, shifted negative exponential, and bunched exponential. A description of the bunched exponential arrival headway distribution is presented, and the results of its calibration using real-life data for single-lane traffic streams and simulation data for multi-lane streams are given. Examples of gap-acceptance capacities and delays predicted by different exponential headway distributions are also presented. Although the bunched exponential distribution is relatively new and its use is less common, it has been found to be more realistic than the negative exponential and shifted negative exponential distributions. Its general use in traffic modelling is recommended.
Original languageEnglish
Pages (from-to)42-59
Number of pages18
JournalRoad and Transport Research
Issue number1
Publication statusPublished - 1 Mar 1994
Externally publishedYes

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Building and Construction

Cite this