Estimation of the share of road fatalities due to driving under the influence of alcohol. In recent years two different estimations were being used of the share of road fatalities due to driving under the influence of alcohol. Both these estimations were based on a method that used different relative rates for drivers with different blood alcohol contents (BAC levels). However, as the rates that were used did not use the same data, the two estimations differed. This, in its turn, resulted in lack of clarity. On request of the Ministry of Infrastructure and the Environment, SWOV has made a new estimation for each year during the period 1999-2010 based on the most recent research data. This new estimation of the share of road fatalities due to the use of alcohol is intended to replace earlier estimations. The estimation is based on the trend of driving under the influence in weekend nights. Risk data is used to firstly convert the trend into an estimated proportion of seriously injured car drivers who were under the influence of alcohol. Two hospital studies which investigated the use of psycho-active substance by seriously injured drivers made it possible to calculate this risk data. The first of these studies was carried out between 2000 and 2004 in the Tilburg region, in the framework of the European research project IMMORTAL. The second study took place in the period 2007-2009 within the European DRUID project and used data of seriously injured car drivers in the regions Tilburg, Enschede and Nijmegen. During the period 1999-2010, the estimated share of seriously injured car drivers who were under the influence of alcohol declined from 31.2% to 20.3%. This decline is based on the decrease of the proportion of drivers who participate in traffic while being under the influence. Between 1999 and 2010, there has been a decline in the proportion of drivers under the influence of alcohol, and, consequently, also of the estimated proportion of seriously injured car drivers who were under the influence of alcohol. This was the case for each of the BAC levels above 0.2‰ that were distinguished. A further estimation of the proportion of alcohol-related fatalities among all traffic fatalities (this is including other modes of transport) required two assumptions. The first of these is that the extent of alcohol use by other active road users equals that of car drivers. The other assumption is that the proportion of road users with fatal injury due to alcohol use is equal to the proportion of seriously injured car drivers that have tested positive for alcohol. This resulted in an estimation of the proportion of road fatalities due to the use of alcohol presently being approximately 20%. An estimated 17% is related to the single use of alcohol and 3% to a combination of alcohol and drugs. The estimation of the present share of road fatalities due to the use of alcohol has entirely been based on the results of the study Driving Under The Influence which was carried out in 2010. Results of that study in future years, however, will need to show whether the recent decline of the estimated proportion of alcohol-related fatalities in relation with preceding years will indeed be continued, or whether it is a chance fluctuation.
Abstract