Rijden onder invloed in de provincie Friesland, 1997-1998 : ontwikkeling van het alcoholgebruik door automobilisten in weekendnachten. In opdracht van het Directoraat-Generaal Rijkswaterstaat, Adviesdienst Verkeer en Vervoer AVV.

In October 1998, the SWOV Institute for Road Safety Research and six police control teams conducted a roadside survey. The aim was to establish the motorists' alcohol consumption in the Dutch province of Friesland. Blood alcohol content (BAC), age and sex of the drivers were collected and recorded. If the recorded BAC level was 0.7 promille or over, places of origin of the offenders were also collected and recorded. The study was carried out on Friday and Saturday nights. The 1997 sample included 1654 motorists. The collected data were analysed using the Weighted Poisson Model (WPM). The results of the 1998 survey are compared with the results of the 1997 survey and with the results of the 1997 national survey