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Guidelines for Using Temporary Traffic Lane Dividers

Temporary traffic lane dividers play a crucial role in protecting both motorists and work crews during road construction projects.  This post will examine the major types of temporary traffic lane dividers in use today and summarize the rules laid out in the MUTCD for their installation and use.

Temporary Raised Islands

These are used to separate traffic flow on two-lane, two-way roads that have daily traffic volumes of between 4,000-15,000 units.  Temporary traffic islands are also used on freeways with average daily traffic volumes of 22,000-60,000 units.  The MUTCD lists the following design specifics for these structures:

  • They should be at least 4 inches high, 18 inches wide, and have rounded edges.
  • They should be designed so that, should a vehicle strike them, the collision would not cause the driver to lose control of the automobile.
  • They should be resilient enough so that vehicle collisions will not cause pieces to break off that could penetrate the vehicle cockpit or cause debris that might endanger other vehicles.
  • When temporary raised islands are installed perpendicular to a pedestrian crossing zone, they must have a gap of at least 60 inches wide to permit those on foot to pass through.


Opposing Traffic Lane Dividers

These are used to divide center lanes, creating a safety zone between vehicles approaching from opposite directions on a two-way, two-lane road.  The MUTCD lists the following design specifics for these structures:

  • They should be marked by an upright, retroreflective, orange sign placed on a flexible base.  The sign must be at least 12 inches wide by 18 inches high.
  • Dividers should never be placed across pedestrian walkways.


Pavement Markings

These are used as either a stand-alone measure or in combination with other temporary traffic lane dividers.  The MUTCD lists the following design specific for these markers:

  • The markings must be visible during both day and evening hours and under both dry and wet pavement conditions.
  • The markings should be placed along the entire length of the temporary roadway or detour prior to opening the section of road to motorists.
  • The markings must be of the same color and style as permanent markings on the road outside the construction zone.
  • The markings must be removed as soon as work is complete.  Schedule planners should ensure that the crews are able to do so before reopening the roadway.
  • In cases where the markings need to be covered up temporarily, work crews may use preformed, non-reflective tape.
  • Temporary markings should not be used for more than two weeks except under the findings of an engineering study.
  • In the case of raised pavement markings, work crews should install retroreflective markers at regular intervals to alert drivers to their presence.


Traffic Delineators

These should be used in conjunction with other temporary traffic control devices.  The MUTCD specifies the following guidelines for their use:

  • They should be mounted on crash-resistant supports so that the reflective surface is approximately 4 feet above the closest roadway edge.
  • White should be used as the standard color for delineators along each side of a two-way street or highway.
  • Yellow should be used as the standard color for one-way roads.


Lighting Devices

The four types of lighting devices used in temporary traffic control zones include flashing warning beacons, steadily burning electric lamps, warning lights, and floodlights.  The MUTCD gives the following guidelines for their use:

  • Floodlights should be placed so as to minimize potential glare for approaching motorists.
  • Flashing warning beacons should be operated 24 hours a day and should have a minimum diameter of 8 inches.



Temporary traffic lane dividers serve an important role in safeguarding highway crews and members of the public.  They should always be used in accordance with established MUTCD rules. For a full treatment on the subject, see the current edition of the MUTCD.