The EuroFOT project executes a large scale FOT that puts more than five hundred instrumented vehicles on the road all over Europe. Most of these vehicles have one or more ITS applications on board and the purpose of the test is to evaluate the societal and individual effects of these ITS, among other on traffic safety. This paper describes the approach taken in EuroFOT to assess the safety impacts of ITS that operate continuously rather than event driven. This approach has some similarities to existing methods but includes some novel aspects to handle the fact that the ITS are continuously active. The paper further describes the first results of the method applied to sample data from the first phase of the FOT.