The present research collaboration aims to integrate epidemiological data and experimental data on drug induced driver impairment and crash risk. Epidemiological data on drug induced crash risk or culpability risk has been collected by Prof Verstraete as part of a European research effort (DRUID) and will be provided by Prof Verstraete for additional, explorative analysis. Experimental data on drug effects on driver impairment will be provided by Prof Ramaekers and consists of concentration/dose-effect data of illicit drug (i.e. cannabis) effects on psychomotor function and on-the-road driving. Dr Kuypers will conduct analysis on both data sets alone or their combination and will define a number of research questions that will fit the present data sets.