Some intersection designs direct some or all traffic to cross over to the left–hand side of the roadway to facilitate unopposed left–turn movements. These designs can improve safety and reduce congestion at the intersection.

The two most common crossover–based designs are the diverging diamond interchange (DDI) and the displaced left–turn (DLT) Intersection.

Outreach and Education Resources

• Alternative Intersection Video Playlist – includes DDI and
  DLT intersections

Diverging Diamond Interchanges

• Diverging Diamond Interchange Brochure
• Diverging Diamond Interchange Case Studies
  • I–44 at State Route 13, Springfield, MO
  • I–15 at Main Street, American Fork, UT
  • I–15 at State Route 92/Timpanogos Hwy, Lehi, UT
  • Georgia's First Restricted Crossing U–Turn Intersections

Displaced Left–Turn Intersections

• Displaced Left–Turn Intersection Brochure
• Displaced Left–Turn Case Studies
  • State Route 30 at Summit Drive, Fenton, MO
  • Bangerter Highway Corridor, Salt Lake County, UT
  • Redwood Road at 6200 South, Taylorsville, UT

Technical Materials and Research

Diverging Diamond Interchanges

• Diverging Diamond Interchange Informational Guide, Second Edition
• Performance of Alternative Diamond Interchange Forms
  • Volume I: Research Report
  • Volume II: Guidelines for Selecting Alternative Diamond Interchanges
• Exploring Corridor Operations in the Vicinity of a Diverging Diamond Interchange (DDI): Final Report
• Comprehensive Safety Assessment Methodology for Innovative Geometric Designs

Displaced Left–Turn Intersections

• Displaced Left–Turn Intersection Informational Guide
• Use of Innovative Intersection Designs for Improving Mobility and Reducing Roadway Traffic Congestion

Connections to Other Transportation Safety Topics

• The Federal Highway Administration's (FHWA) EDC–2 initiative for Intersection and Interchange Geometrics developed educational materials about DDIs, DLTs, and other intersection designs
• Roundabout, restricted crossing U–turn (RCUT) , and median U–turn (MUT) intersection designs also offer improved safety due to fewer conflict points
• Intersection Control Evaluation (ICE) policies and tools can help agencies choose an optimal intersection design
• Low–cost strategies and countermeasures can improve safety. Learn more at Stop–Controlled Intersection Safety and Signalized Intersection Safety