Roadways: Medians

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Medians

Primary Guidance

  • Width
  • Is the distance between opposing directions from the edge of traveled way of each direction, including shoulders.
  • Consider the potential need for median traffic barrier, but where practical, the median should be designed to not need traffic barrier.
  • The wider the median, the larger the footprint impacts the surrounding topography.
  • In urban areas with constrained right of way, larger median widths will likely be impractical.
  • Urban closed section medians at signalized intersections with crosswalks should be at least 6 feet wide for pedestrian refuge.
  • Rural open section medians should be at least 30 feet with ADT less than 40,000, 50 feet with 40,000<ADT<80,000, 75 feet ADT greater than 80,000. If these median widths are not attainable, traffic barriers will be warranted.
  • Traffic barriers will be warranted if sufficient median widths are not provided. However, barrier placement should be minimized where practical.
  • Should be provided on high type facilities, arterial or higher, with four or more lanes.
  • Intended to provide opposing traffic separation, errant vehicle recovery area, stalled vehicle stopping area, potential storm-water management area, future widening allowance, left turn bay storage and speed change space, speed change lanes, and green spaces and pedestrian refuges for crosswalks in urban areas.
  • Can be depressed, raised, or flush with the traveled way surface.

Discussion

  • Rural divided highways should consider the widest median practical at un-signalized intersections. The median should be wide enough to accommodate the actual vehicles that will make the turning or U-turn movements at the median opening. The appropriate design vehicle is critical to the design of the median width. It may be necessary for the median to be wide enough to accommodate the storage of the design vehicle storage without any part of the vehicle encroaching on the traveled way while stopped within the intersection. Signalized intersections on rural highway may not benefit from a larger median due to the additional time that will be needed for vehicle to travel through the intersection.
  • Urban and suburban highway operate better with narrower medians. Therefore, wider medians should only be considered where there is a need to accommodate a larger design vehicle turning movements. For signalized intersections in urban and suburban areas with pedestrian and bicycle movements, consider pedestrian refuges within the median, especially when there are more than four lanes to cross. If the corridor is likely to develop and warrant the need for left turn movements, the median width should be able to accommodate the turn lane along with a pedestrian refuge. Auxiliary lane widths and median widths at the future turning movements need to consider the design vehicle that will be using the left turn movement.