These devices can be used in Public transport as a valuable research tool to monitor or validate new safety technology, to establish human tolerance limits and to record impact speeds. Black boxes can also be used to influence driving behavior and facilitate forms of automatic policing (100% surveillance of all traffic offences). Offenders can be tracked more easily and fined automatically by means of devices such as Electronic Vehicle Identification. At the same time the system can be used to reward safe behavior and to reduce insurance premiums. Two types of in-vehicle data recorders are currently used: