Vehicle Loading in Traffic Simulation Models

Microscopic traffic simulation models are becoming increasingly popular and used to address a wide range of problems, from planning to operations. Furthermore, hybrid models that combine mesoscopic and microscopic models to simulate large scale networks are emerging. Despite the significant progress though, a potentially important process, the loading of vehicles onto the network, has not received much attention. If vehicles are assigned their initial speeds improperly, especially in congested networks, unnecessary turbulence may be created that will result in artificially reduced capacity of the loading link. The paper reviews existing loading methods (employed by the state of the art models MITSIMLab and VISSIM) and demonstrates the sensitivity of the simulation results to the initial speed. The results show that loading has a significant effect on the initial acceleration behavior of the loaded vehicles, and the (implied) capacity of the first segment of the entry link. The paper proposes four alternative loading approaches and identifies one as theoretically sound and consistent. A case study demonstrates that the new method is robust, and performs well even under congested conditions. The proposed method is useful not only for loading vehicles in microscopic models but also in the context of hybrid models for transferring vehicles from the meso to the micro network.


  • English

Media Info

  • Media Type: CD-ROM
  • Features: Figures; References;
  • Pagination: 13p
  • Monograph Title: TRB 86th Annual Meeting Compendium of Papers CD-ROM

Subject/Index Terms

Filing Info

  • Accession Number: 01049526
  • Record Type: Publication
  • Report/Paper Numbers: 07-0781
  • Files: TRIS, TRB
  • Created Date: Feb 8 2007 5:22PM