17.7.1 Application

On high-speed highways (50 mph or greater), median barriers should be considered based on the criteria shown in
Table 17-3
. Flush medians or frequent crossovers may preclude the use of median barriers based on an engineering analysis of individual locations.
Table 17-3: Recommended Guidelines for Installing Median Barriers on High-Speed Highways
Recommended Guidelines for Installing Median Barriers on High-Speed Highways ( click in image to see full-size image)
The criterion is divided into two different zones by various combinations of average annual daily traffic and median width.
  • Barrier Recommended -
     Barrier should be installed.
  • Evaluate Need and Cost Effectiveness of Continuous Barriers.
    (Point obstacle protection may be appropriate for specific locations)
     - An engineering analysis should be performed to determine if barrier is needed for reducing the occurrence of cross-median encroachments (crashes). This analysis may consider the following:
    • Type of median (flush, depressed [V-ditch or flat-bottom]);
    • Width of the median (measured from edges of travel lane for opposing directions of travel);
    • Traffic volumes, including estimated traffic growth and percent trucks (10% or greater);
    • Types and severity of crashes;
    • Posted speed limit;
    • Type of facility, including controlled access or non-controlled access with crossovers;
    • Roadway alignment;
    • Ramp locations; and
    • Elimination of barrier gaps.
Continuous barrier should be limited to areas where it is needed to reduce cross-median incidents and should not be used for point obstacles (e.g.; overhead sign bridges, etc.), or in areas of lesser concern (e.g., wider medians, forested areas, etc.).