Simplified Capacity Concepts for Access Management

Capacity estimates are essential in developing and assessing access management projects and in determining lane requirement for arterial roads. There is an important need for approaches that can quickly respond to changes in site plans and roadway configuration, both in the field and in the office. The paper presents several capacity concepts that respond to this need and that reflect the uncertainties and variations of future traffic estimates. One approach involves estimating future lane requirements based upon daily traffic volumes per lane and available green-per-cycle ratios. A second approach shows how signalized intersection capacity can be estimated where vehicles in left lanes move on the same phase as the through traffic. Here, the available green time is allocated between the through movement and the opposing left turns. It is an adaptation of the critical movement procedure that takes into account traffic signal timing. A third approach describes a simplified technique for dealing with shared left turn lanes at signalized intersections. Results are compared with Australian, Canadian and Highway Capacity Manual procedures for typical volume conditions. It shows that shared lanes are typically about 40 to 60% as effective as through lanes. Finally, the paper identifies other areas where simplified procedures would be useful.


  • English

Media Info

  • Media Type: Web
  • Features: References; Tables;
  • Pagination: 24p
  • Monograph Title: Sixth National Conference on Access Management, August 29-September 1, 2004, Kansas City, Missouri

Subject/Index Terms

Filing Info

  • Accession Number: 01046460
  • Record Type: Publication
  • Files: TRIS, USDOT
  • Created Date: Apr 24 2007 2:24PM