9B-5: Warning Lights

Warning lights are used to indicate and delineate the safe path of travel. Flashing lights are to be mounted on barricades singly to indicate an obstacle on or adjacent to the roadway. Flashers are also effectively used to draw attention to warning signs in the traffic control zone.  Steady-burn warning lights may be used at night on barricades or other channelizing devices to delineate the safe travel path.

Barricade lighting offers an extra measure of protection for nighttime traffic movements through a work area, especially in the following situations:

• Where reflectorized panels may be covered with dust or snow;
• In times of decreased visibility due to rain, snow, or fog;
• On barricades that are on curves, around corners, and in driveways;
• For alerting pedestrians and cyclists who travel without headlights;
• At dangerous locations and for channelization on high-speed highways.

Shown below are the principal types of warning lights and their uses.

• Type A low-intensity flashing lights are appropriate for use on a channelizing device to warn of an isolated obstacle at night or to call attention to warning signs at night.
• Type B high-intensity flashing lights are appropriate to use on advance warning signs day and night.
• Type C steady-burn lights are intended for use on a series of channelizing devices or on barriers to delineate the traveled way through and around obstructions in a temporary traffic control zone. However, since the department requires channelizing devices to be reflectorized with Type III or Type IV sheeting, Type ‘C’ steady-burning lights are not used in Iowa.  For more information regarding reflective sheeting, refer to current Iowa DOT specifications for traffic control devices.

Chronology of Changes