Access Control near Highway Interchanges

• Authored by:  Paul Grasewicz
• Event:  2012 National Conference on Access Management

Objectives

• 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.”