Presentation | 2013

Access Control near Highway Interchanges


  • Review origin of current guidelines for access separation from interchange ramps
  • Review recent Virginia study on the relationship between access spacing from interchange ramps and crash rates
  • Suggest new standards for the optimum access point spacing

Findings and Recommendations: Access Spacing from Interchange Ramp

  • Key findings include:
    • Regardless of geometric and traffic factors, the crash rate:
      • Is dramatically lower at 750 ft and 990 ft spacing from ramps
      • Is minimal at 1,320 ft
    • No safety improvement: 2,640 ft (1/2 mile) spacing vs. 1,320 ft (1/4 mile)
    • No significant difference between urban and rural ramps.
  • Safety justification for managing access near ramps – easy to understand, practical, politically acceptable.
    • Example:  VA Governor’s Transportation Strategic Plan goal:
      • “Improve safety across all modes of transportation by reducing transportation related injuries, fatalities, crashes.”
Functional Intersection Area, Interchange
access control, interchanges, spacing