A great need exists for lower-cost design strategies to reduce congestion on major suburban arterials on which conventional techniques have been exhausted. This study examines the possible gains in travel efficiency from three unconventional strategies: the median U-turn, in which left turns are made using crossovers on the arterial approximately 180 m from the main intersection; continuous green T-intersection (CGT), in which one or two lanes at the top of the "T" receive a constant green indication; and the North Carolina State University (NCSU) Bowtie, developed during the project, in which left-turning traffic uses roundabouts on the side street approximately 180 m from the main intersection. The study used Traf-Netsim 4.0 to simulate the unconventional configurations and a conventional intersection for comparison in three factorial experiments. The experiments showed that the unconventional alternatives have the potential to provide for more efficient travel. The CGT configurations reduced travel time and stops substantially at three-legged intersections for through volumes of more than 400 vehicles per hour per lane. The median U-turn became more efficient than the CGTs at higher through volumes. An experiment with a four-legged intersection showed that the NCSU Bowtie reduced travel time and stops from the conventional configuration at about 900 or more critical through vehicles per hour. Questions remain about the unconventional strategies, but that they potentially provide for more efficient travel is clear.


  • English

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 153-161
  • Monograph Title: Geometric design, roadside safety features, roadside hardware monitoring, and scenic loop tours
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00715003
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Dec 26 1995 12:00AM