A Procedure to Estimate the Effect of Autonomous Vehicles on Freeway Capacity

Autonomous vehicles (AVs) are anticipated to improve traffic operations, but the magnitude of their effect on traffic flow is not yet known since the technology is still under development. However, transportation planners and engineers need to know how AVs will affect roadway capacity when developing projects to accommodate future transportation demand. The Highway Capacity Manual (HCM) provides the procedures to evaluate future conditions, but the methodologies are based on empirical research of existing facilities, which do not yet include AVs. To account for the capacity effect of AVs, the HCM procedure for calculating the demand flow rate under base conditions is proposed to be revised to add an adjustment factor for AVs. To develop the AV adjustment factor, traffic simulation analysis software can be applied since it provides the ability to model conditions that are not yet observable, such as a high percentage of AVs in a traffic stream. Given the complex nature of microscopic simulation tools, guidance for modeling AV capacity effects is needed. This paper presents a procedure for using traffic simulation software to develop capacity adjustment factors for AVs. A case study using a previously developed AV driving behavior is described to demonstrate the application of the procedure to estimate the effect of AVs on freeway capacity.

  • Supplemental Notes:
    • This paper was sponsored by TRB committee AHB40 Standing Committee on Highway Capacity and Quality of Service.
  • Corporate Authors:

    Transportation Research Board

  • Authors:
    • Stanek, David
  • Conference:
  • Date: 2019


  • English

Media Info

  • Media Type: Digital/other
  • Features: Figures; Photos; References; Tables;
  • Pagination: 10p

Subject/Index Terms

Filing Info

  • Accession Number: 01698181
  • Record Type: Publication
  • Report/Paper Numbers: 19-03588
  • Files: TRIS, TRB, ATRI
  • Created Date: Dec 7 2018 9:48AM