Carbohydrate-deficient transferrin (CDT) was quantified in 408 blood specimens, randomly selected from 1260 drivers apprehended and submitted to blood alcohol concentration (BAC) determination. The first step of the study was to observe whether a BAC based pre-evaluation was relevant for deciding to test drivers for chronic alcohol abuse. For this purpose, the diagnosis of chronic alcohol abuse was verified by CDT quantification, with a voluntary high positive cut-off fixed at 3% for high specificity. The results display a significant increase in the part of chronic alcohol abusers with respect to increasing BAC: a few alcohol abusers were present in the BAC category below 0.5 g/L, and their frequency increased to 47 and 67% when BAC was between 3 and 3.5 g/L and above 3.5 g/L, respectively. Secondly, the usefulness of the biomarker CDT in the traffic safety context was investigated by observing whether drivers with abnormally increased CDT value had also higher BAC. The average BAC was 1.32 g/L in drivers with CDT below 1%, and increased to 2.28 g/L in drivers with CDT above 3%. Statistical analysis showed evidence of a monotone increasing link between BAC and CDT (P<0.0001). We confirmed here the relevance of BAC-based pre-evaluation before testing chronic alcohol abuse among drivers, and demonstrated that CDT is a biomarker suitable for traffic safety context, as drivers with increased CDT had significantly higher BAC.