Can radar detectors and safety warning system (SWS) signals improve road safety?

The relationship between speed, crash risk and crash severity is well documented. In-vehicle radar detectors are small, specialised radio receivers tuned to the frequency range used by police radar guns. These devices make it possible for drivers to detect police radar efforts and to alter their travel speed. Safety Warning Systems (SWS) emit pre-programmed radar signals that can be received by radar detectors up to one kilometre away, and can provide warnings to an equipped vehicle regarding potential road safety hazards. SWS have been promoted by some as inexpensive and practical warning devices that can be used within existing infrastructure; however, it is unclear whether any potential benefits would outweigh speeding-related costs. An independent review of the survey, observational and crash data literature pertaining to SWS and radar detectors was conducted. Collectively, the literature indicates that, because radar detectors are used predominantly by an already high-risk group of drivers, their application as receivers of SWS signals is unlikely to result in overall benefits to road safety.