Automatic speed enforcement

Description
The amount of drivers driving faster than the speed limit can be reduced by enforcing speed limits more efficiently. Speed enforcement may be manual work carried out by the police or it may be automated. In many cases, automatic speed enforcement is based on measuring speeds of vehicles in a point and photographing the offending drivers¨ and their vehicles. Speed enforcement may also be based on measuring travel times of vehicles between to points whose distance is known.

Impacts
Automatic speed enforcement can reduce the number of fatal and injury accidents by 17 %. The speed standard deviation also decreases.

Studies

The amount of fatal and injury accidents decreases by 17 %.	Literature study and analysis of previous studies.	Elvik, R., Mysen, A. B., Vaa, T.	1997	Trafikksikkerhetshåndbok. Tredje utgave. Oslo, Transportøkonomisk institutt.
Mean spot speeds decreased at all six measurement points by 1.5–4.4 km/h (speed limit 100 km/h) after automatic enforcement was introduced. The effect was almost the same a year after the beginning of enforcement (the speeds decreased by 1.1–3.5 km/h). As a control, speed data from five other measurement points outside the surveillance road section was collected. They did not show the decrease in mean spot speeds.	Results are based on before-and-after study with spot speed measurements.	Räsänen, M., Beilinson, L. & Kallberg V-P.	2004	Automaattisen kameravalvonnan nopeusvaikutukset kantatiellä 51 [Speed effects of automated camera enforcement on main road 51]. Finnra reports 53/2004, Finnish national road administration.
When operating at maximum coverage, the Queensland speed camera program was estimated to have produced a reduction in fatal crashes of around 45% in areas within 2km of speed camera sites.	Crash trends in areas within 6km of the camera site to areas further than 6km from camera sites both before and after introduction of the program were compared.	Newstead, S. W., Cameron, M. H.	2003	Evaluation of the crash effects of the Queensland speed camera program. Monash university accident research centre.
Automatic speed enforcement lowered mean speeds by 2,8 km/h measured at 2 km forward from treatment area. The speed standard deviation also decreased by 0,5 km/h. Corresponding to speed reduction, the study revealed 16 +- 7 % reduction in expected collisions along the study corridor as a whole.	Before-and-after study	Chen, G., Meckle, W. & Wilson, J.	2002	Speed and safety effect of photo radar enforcement on a highway corridor in British Columbia. Accident Analysis and Prevention 34, pp. 129-138
Automatic speed enforcement reduced the the numer of injury accidents by 20 %. The result was statistically significant.	Before-and-after study	Elvik, R.	1997	Effects on Accidents of Automatic Speed Enforcement in Norway. Transportation Research Record 1595, USA.