Towards a large scale European Naturalistic Driving study: final report of PROLOGUE: deliverable D4.2 van SchagenIngrid WelshRuth Backer-GrondahlAgatha HoedemaekerMarika LotanTsippy MorrisAndrew SagbergFridulv WinkelbauerMartin 2012 Naturalistic Driving (ND) studies represent the state of the art in traffic safety research and can be defined as studies undertaken to provide insight into driver behaviour during every day trips by recording details of the driver, the vehicle and the surroundings through unobtrusive data gathering equipment and without experimental control. Typically, in an ND study passenger cars, preferably the subjects' own cars, are equipped with several small cameras and sensors. For several months to several years, these devices continuously and inconspicuously register vehicle manoeuvres (like speed, acceleration/deceleration, direction), driver behaviour (like eye, head and hand manoeuvres), and external conditions (like road, traffic and weather characteristics). Thus, the ND approach allows us to observe and analyse the interrelationship between driver, vehicle, road and other traffic in normal situations, in conflict situations and in actual crashes. This type of information is not just useful for reducing road transport casualties, but also for reducing the environmental burden of road transport, and for reducing congestion. ND studies are not limited to passenger cars since vans and trucks can also be studied in a naturalistic way. Similarly, motorcycles can be equipped: naturalistic riding. The specific problems of pedestrians and cyclists can be studied based on observations from the vehicle. However for this application, naturalistic site-based observations can be a useful addition.