[Automobile driving studies to determine alcohol-induced driving insecurity after dark]

To further elucidate the question whether the criteria for assessing alcohol-induced unfitness to drive should be stricter for night-time than for day-time driving (cf. Schewe et al., 1977) 64 test persons performed automobile driving tests in daylight and in darkness while being sober and while under the influence of alcohol. The first set of tests was done in daylight. A test course of approx. 600 m involving six everyday driving maneuvers had to be covered, first in the sober state and then at blood alcohol concentrations (BAC) of 1.1 g % and 1.4 g %. The driving tests in the dark were performed on the same test course, first in the sober state and then at a BAC of 1.1 g%. In both test series the errors were counted and the driving times measured. Statistical evaluation of the test results was done parametrically (t-test for dependent random samples) and distribution-free (Wilcoxon's test for paired comparison). In the sober state 2.1 errors were made on average during the day and 3.2 errors, i.e. one error more, at night. At 1.1 g %, 4.3 errors occurred during the day but 8.0 errors at night (i.e. 3.7 errors more than during the day). The differences were statistically significant. With 8 errors during night-time driving at 1.1 g % the number of errors was still higher than the average number of 6.8 errors made during day-time driving at 1.4 g %. The average driving times required in the sober state were 241 s during the day and 256 s at night. At 1.1 g %, 243 s were needed during the day and 272 s at night, i.e. on average 17 s more than for day-time driving at 1.4 g % for which 255 s were needed. For an orienting comparison of driving performance it can be assumed that "performance" in the sense meant here is reciprocally proportional to the number of errors and reciprocally proportional to the time required, i.e. on the whole reciprocally proportional to the product from number of errors and time. The deterioration of performance can be illustrated best by assuming performance in the sober state during the day to be 100% and relating the other "performances" thereto.(ABSTRACT TRUNCATED AT 250 WORDS)