Displaced Left-Turn Interchange

Today's transportation professionals, with limited resources available to them, are challenged to meet the mobility needs of an increasing population. At many highway junctions, congestion continues to worsen, and drivers, pedestrians, and bicyclists experience increasing delays and heightened exposure to risk. Today's traffic volumes and travel demands often lead to safety problems that are too complex for conventional interchange designs to properly handle. Consequently, more engineers are considering various innovative treatments as they seek solutions to these complex problems. The corresponding technical report, Alternative Intersections/Interchanges: Informational Report (AIIR) (FHWA-HRT-09-060), covers four intersection designs and two interchange designs that offer substantial advantages over conventional at-grade intersections and grade-separated diamond interchanges. The AIIR provides information on each alternative treatment covering salient geometric design features, operational and safety issues, access management, costs, construction sequencing, environmental benefits, and applicability. This TechBrief summarizes information on one of these alternative interchange designs-the displaced left-turn (DLT) interchange. The DLT interchange is a new interchange design that has similarities to both the at-grade DLT intersection and the double crossover diamond (DCD) interchange. The main feature of the DLT interchange is that left-turning traffic crosses over the opposing through lanes several hundred feet upstream of the main intersection and then proceeds on a new roadway situated between the opposing through lanes and a roadway that carries right-turning traffic from the ramp. From this new roadway, the left-turn traffic completes its maneuver onto the on-ramp.


  • English

Media Info

  • Media Type: Digital/other
  • Features: Figures;
  • Pagination: 4p
  • Serial:
    • TechBrief
    • Publisher: Federal Highway Administration
  • Publication flags:

    Open Access (libre)

Subject/Index Terms

Filing Info

  • Accession Number: 01149570
  • Record Type: Publication
  • Report/Paper Numbers: FHWA-HRT-09-056
  • Files: NTL, TRIS, USDOT
  • Created Date: Jan 13 2010 1:13PM