The light weight and portability of warning lights are advantages that make these devices useful as supplements to the retroreflectorization on hazard warning devices. The flashing lights are effective in attracting a driver's attention and, therefore, provide an excellent means of identifying the hazard.
As used herein, warning lights are portable, lens-directed, enclosed lights. The color of the light emitted shall be yellow. They may be used in either a steady-burn or flashing mode. Warning lights shall be in accordance with the current ITE Purchase Specification for Flashing and Steady-Burn Warning Lights.12
12 Included in the Equipment and Material Standards of the Institute of Transportation Engineers Publication No. ST 017; 525 School Street, S.W., Suite 410, Washington, D.C. 20024. Telephone: 202-554-8050.
Warning lights shall have a minimum mounting height of 30 inches to the bottom of the lens. Type A low-intensity flashing warning lights are most commonly mounted on barricades, drums, vertical panels, or advance warning signs, and are intended to warn drivers that they are approaching or in a hazardous area.
Type A low intensity flashing warning lights and Type C steady-burn warning lights shall be maintained so as to be visible on a clear night from a distance of 3,000 feet. Type B high intensity flashing warning lights shall be maintained so as to be visible on a sunny day, when viewed without the sun directly on or behind the device from a distance of 1,000 feet.
Type B high-intensity flashing warning lights are normally mounted on advance warning signs or on independent supports. Extremely hazardous site conditions within temporary traffic control zones may require that the lights be effective in daylight as well as dark. They are designed to operate 24 hours per day. Flashers shall not be used for delineation, as they would tend to obscure the desired vehicle path.
Type C steady-burn lights are intended to be used to delineate the edge of the traveled way on detour curves, on lane changes, on lane closures, and on other similar conditions.