The National Academies

NCHRP 15-30 [Final]

Median Intersection Design for Rural High-Speed Divided Highways

  Project Data
Funds: $200,000
Research Agency: Iowa State University
Principal Investigator: Thomas Maze
Effective Date: 8/1/2005
Completion Date: 12/31/2008


The objective of this project was to recommend improvements to the rural median intersection and crossover design information in the AASHTO Policy on Geometric Design of Highways and Streets (Green Book) and the Manual on Uniform Traffic Control Devices (MUTCD) for high-speed (50 mph and faster) divided highways with partial or no control of access. The recommendations cover geometric plan layout and traffic control devices.


The report has been published as NCHRP Report 650.


There has been a substantial amount of recent work on various aspects of median intersection design, but much of it is not yet reflected in national guides. In addition to typical four- and three-legged intersections, updates are needed for median crossovers without an intersecting roadway.


Task 1. Summarize the guidance on median intersection and crossover design currently in AASHTO publications and the MUTCD. Identify areas where guidance is lacking or needs to be expanded or supplemented.

Task 2. Review recent relevant literature to identify safe and effective median intersection and crossover design treatments. Topics of particular interest are truck accommodations, needs of older drivers, the effect of signalizing an intersection, the interaction of intersections with nearby horizontal and vertical curvature, signing and pavement markings, and turning and acceleration bay designs.

Task 3. Identify and contact agencies with experience using innovative treatments at median intersections and crossovers to determine their effects.

Task 4. Develop recommended text for the Green Book and MUTCD on median intersection and crossover design.

Task 5. Identify and describe topics warranting further study, including retrofitting existing intersections and crossovers.

Task 6. Submit a final report documenting the research effort and including the Task 4 recommended text as an appendix.

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