This study assessed driver reactions to 16 road hazard warning signs of various formats by projecting life-sized video of road scenes to drivers in a driving simulator. A range of measures, including attentional and search conspicuity, implicit and explicit recognition, dynamic and static comprehension, and sign priming were collected. Of the signs tested, road works and school warning signs were most often detected, remembered, and understood. Slippery surface warnings were associated with some of the lowest detection and comprehension rates. The effectiveness of the different formats depended on the type of hazard sign. In the case of road works warnings, a flashing variable message format was only slightly more conspicuous than the large dimension format, equal in comprehensibility, and perhaps somewhat worse in terms of memorability. For the school warnings, however, the flashing variable message format appeared to convey a greater sense of potential hazard, produced superior search conspicuity and priming, and was equal in terms of memorability and comprehensibility. The range of measures worked well as a whole with the two measures of conspicuity and the measure of static comprehension showing the greatest consistency. (c) 2005 Elsevier Ltd. All rights reserved.
