Jean-Francois Peytavin

SAM Survey on “Drugs and Fatal Accidents”: Search of Substances Consumed and Comparison between Drivers Involved under the Influence of Alcohol or Cannabis

Objectives. A survey was conducted to produce reliable epidemiological data concerning the role played by alcohol and drugs in fatal road accidents in France. The aims are to describe the conduct of the survey, evaluate the overall quality of the findings, and analyze the substances consumed by the involved drivers. A comparison between drivers involved under the influence of alcohol only, cannabis only, or both substances is emphasized. Methods. By a June 1999 law, all drivers in France involved in an immediate fatality accident between October 2001 and 2003 had to undergo a urine test and, if that was not possible or the test proved positive, had a blood sample taken in order to test for drugs (cannabis, cocaine, heroin, amphetamines). The results were combined with the usual procedures of the police force, which include the results of tests for illegal alcohol levels. A unique and reliable set of accident data on the role of drugs was thus compiled for epidemiological purposes: 10,000 accident reports involving over 17,000 drivers were analyzed. The responsibility level of each driver involved in an accident was determined. Results were generated for a representative sample of about 11,000 drivers. Results. Alcohol levels above the legal limit (0.5 g/L of blood) were found in 21% of all drivers involved in accidents (killed, injured, or unharmed). Cannabis headed the list of illicit drugs detected, with a prevalence of 6.8% (THC ≥ 1 ng/mL); it was present in the under-35s and especially the under-25s. About 40% of drivers under the influence of cannabis also had an illegal alcohol level. The other drugs, whether alone or in association with cannabis, are relatively rare. Accident characteristics of drivers detected positive for cannabis only are markedly different from drivers under the influence of alcohol. The overrepresentation of drivers responsible, from 1.7 over the whole population, rises to 2.3 for cannabis alone (THC ≥ 1 ng/mL), to 9.4 for alcohol alone (≥0.5 mg/L), and to 14.1 for the alcohol-cannabis combination. Conclusions. The high incidence (26%) of alcohol or drugs among the population of drivers involved in fatal accidents highlights the importance for road safety of the consumption of these substances. Alcohol remains the major risk at any age. Young drivers consuming alcohol and cannabis represent a priority target for prevention.

Time Headway on French Rural Roads

Abstract This paper presents some empirical time headways observed on rural roads in France, and proposes a model relating the time gaps to the traffic flow, to the percentage of long vehicles, to the number of lanes; the influence of the period of the day is discussed. The parameters of the models characterise either the random arrivals, or the drivers behaviour. Their evolution in the future will show how the new French legislation on time gaps (to drive at a minimum threshold of two seconds) is respected.