Rensselaer Polytechnic Institute. Lighting Research Center

C-08-22

Tech Report

New York

New York (State). Dept. of Transportation

Rotating beacons containing filament light sources have long been used on highway maintenance trucks

to indicate the presence of the truck to other drivers. Because of advances in light-emitting diode (LED)

technologies, flashing lights containing LEDs are beginning to be used in place of conventional rotating

beacons. These devices use considerably less power, an important consideration for an equipment-laden

maintenance truck. To ensure that LED beacon lights will provide a comparable warning signal to

drivers approaching vehicles outfitted with them, their photometric and temporal characteristics were

measured and compared to human response time data. In addition, several LED beacon light fixtures

were compared to conventional rotating beacons in terms of the distance at which observers could detect

that a vehicle had moved closer to the observer (the longer this distance, the better performance is).

LED beacon lights provided equivalent closure detection distances as conventional rotating beacons, as

long as they were used in pairs as per common practice. Closure detection distances when only one

beacon light was present were statistically significantly shorter. Overall, the results suggest that using

LED beacon light fixtures provides comparable visual information to other drivers, while using

substantially less power.

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US Transportation Collection