Improving the Effectiveness of Nighttime Temporary Traffic Control Warning Devices, Volume 1: Evaluation of Lights on Nighttime Work Zone Channelization Devices

Currently, the Illinois Department of Transportation (IDOT) is one of the few state transportation agencies that require warning lights on nighttime work zone channelization devices, such as drums and barricades. The intent of the steady-burn, amber warning lights is to increase visibility of the channelization devices, providing guidance to motorists and preventing intrusions into the closed lane. However, their additional benefit beyond that provided by the high-reflectivity materials used on the channelization devices themselves has not been evaluated, including taking into consideration their initial, maintenance, and replacement costs; and the environmental and economic issues of routine battery replacement.

Applied Research Associates, Inc. (ARA) studied the effectiveness of warning lights on nighttime channelization devices by reviewing pertinent literature, experimental studies of nighttime work zones with and without lights on drums, driver surveys, and focus groups of driver perceptions and behavior in work zones using traffic drums.  Researchers applied a cognitive model of driver mental processes to this information to determine the influence of drum warning lights, if any, on driver perception and response.

The research showed that, when unprompted, most drivers did not perceive a difference or respond any differently in nighttime work zones using lights on drums than in those without lights. However, when asked to make direct comparisons between work zones with and without lights on drums, there was a slight preference for lights on drums due to the perceived increase in nighttime lighting they provide. Nighttime work zones, and work zones in general, are visually cluttered environments; and the presence (or absence) of lights on drums was not significant enough to attract the drivers’ attention, given competing visual cues such as work zone traffic control devices, other vehicles, and activities in the work space. In addition, the reflective prismatic sheeting on drums in Illinois provides sufficient visibility without warning lights.