ROAD MARKINGS AS AN ALCOHOL COUNTERMEASURE FOR HIGHWAY SAFETY: FIELD STUDY OF STANDARD AND WIDE EDGELINES. ABRIDGMENT

Reflectorized road markings have long been recognized as a cost-effective means of reducing road accidents, particularly at night. In recognition, first, of the need to reduce the 50 percent of fatal road accidents that involve alcohol-impaired drivers, and second, of the high incidence of alcohol impairment at night, this study sought to determine whether wider-than-standard edgelines would serve as an alcohol countermeasure. A vehicle positional study was conducted on two-lane rural roads in northern New Jersey in which four edgeline width conditions (0, 4, 6, and 8 in.) were evaluated. From lateral position measurements taken photographically every 100 ft., driver performance was analyzed by using six different methods. The 16 male test subjects each drove twice--one after they consumed placebo drinks (0.00 blood alcohol concentration (BAC)), and the other time after they consumed either placebo drinks or a controlled alcohol dosage (0.05 or 0.08 BAC). Prior research was corroborated in that the test subjects showed improved driving performance when edgelines were present and reduced performance when they were alcohol impaired. The presence of wider-than-standard edgelines was found to incrementally enhance the benefits derived from standard 4-in. wide edgelines for both unimpaired and alcohol-impaired drivers. When alcohol is present, even at the relatively low BAC levels examined in this research, the visual communication link between the roadway and the driver is interrupted. The improved driving performance of the test subjects in the presence of wide edgelines indicates that strengthening the visual signal at the road edge may compensate to some degree for alcohol impairment and hence reduce the risk of accidents. Since the effects of alcohol on driver vision are similar to the effects of fatigue, drugs, and reduced visual ability due to old age, wide edgelines are likely to also benefit those with these other types of impairment. (Author)