Differences in Gap Acceptance of Elderly Drivers and the Impact on Traffic Simulation Modeling

The objectives of this project were to conduct field studies of driving behavior classified by age category to identify differences in gap acceptance decisions between elderly and other drivers. The authors focused on left turns at unsignalized intersections, where drivers must evaluate gaps in oncoming traffic and decide whether or not it is safe and comfortable to execute a left turn maneuver through each gap. Their approach was to observe the operation at unsignalized intersections where there are a substantial number of left turning vehicles and after classifying drivers by age range, and note the lengths of all gaps each declines and uses. They controlled for physical characteristics of intersections, including presence and absence of left turn lanes, number of oncoming traffic lanes, and speed of oncoming traffic. Statistical analysis was used to identify whether or not older drivers choose different gaps for turning left, and under which conditions these differences are most significant. The authors then incorporated the resulting gap distributions in simulations of the intersections studied to confirm that accounting for the actual gap acceptance behavior of the drivers improves the fidelity of the simulation. They also noted the conditions under which differences in gap acceptance behavior are greatest, to provide information about how best to improve intersections to help make this maneuver less dangerous and more comfortable for senior drivers, and thus, for the general population as well. The most notable findings include: 1. Drivers above age 70 are much less likely to accept shorter gaps than other drivers. This suggests that elderly drivers compensate their diminished perception reaction ability by taking a more conservative driving attitude. However, drivers of age between 55 and 70 show no significant differences in gap acceptance behavior compared to younger drivers. This is consistent with other research finding that driver perception and acuity does not significantly begin to drop until age 70. 2. Other factors that have significant effect on gap acceptance decisions include gender and speed limit. Female drivers are more conservative than male drivers, as found in most previous studies. Speed has interacting effect with the gap duration. Shorter gaps are more likely to be accepted in a high speed setting than in a low speed setting, indicating that distance to the oncoming vehicle might be the variable associated with driver perception of gap sufficiency. 3. Simulations in CORSIM with the default gap acceptance distribution and the distribution resulting from the statistical model that consider the actual driver composition under existing traffic conditions show very similar MOEs.

  • Record URL:
  • Supplemental Notes:
    • This document is disseminated under the sponsorship of the Department of Transportation, University Transportation Centers Program.
  • Corporate Authors:

    New England University Transportation Center

    Massachusetts Institute of Technology
    77 Massachusetts Avenue, Room 40-279
    Cambridge, MA  United States  01239
  • Authors:
    • Ivan, John N
    • Garder, Per E
  • Publication Date: 2009-11-30


  • English

Media Info

  • Media Type: Web
  • Edition: Final Report
  • Features: References;
  • Pagination: 3p

Subject/Index Terms

Filing Info

  • Accession Number: 01152842
  • Record Type: Publication
  • Report/Paper Numbers: UCNR19-10
  • Files: UTC, TRIS
  • Created Date: Mar 16 2010 10:16AM