Report numberRA-2006-90
TitleEffectiveness of automated cameras
SubtitleData from five police zones
AuthorsErik Nuyts
Published byPolicy Research Centre for Traffic Safety 2002-2006
Number of pages34
Document languageDutch
Work packageOther: Infrastructure and space

In a previous report, the Flemish Policy Research Centre for Traffic Safety investigated the effect of automated red light and speed cameras on traffic safety, based on 3 roads in a single police zone, with a post-period of 1 year (Nuyts, 2004). This research is extended to 11 roads in three police zones, with post-periods up to 3 years. Moreover, results are compared with data from two other police zones where automated cameras are used together with other traffic safety measures. Hence, the present conclusions are more representative for Flanders (Belgium) than those from the former report.


The effectivity of the cameras is calculated taking into account the regression to the mean and the general accident trend. This is done by using a comparison group.

  • The best estimate of the effect of the Flemish automated cameras is a significant reduction of all accidents of 20% à 21% in the number of all types of accidents (including both accidents with and without injuries). This reduction is in line with the internationally published results.
  • The effect of the Flemish automated cameras on injury accidents is less pronounced: a non-significant reduction of 7% to 9%. This reduction is lower than the internationally published results.
  • Contrary to what mostly is found, the cameras in Flanders were less effective for injury accidents than for all accidents.
  • The effect of camera boxes, that were never allowed to have working cameras, but with dynamic information sign “You are driving too fast” is comparable to the effect of camera boxes with working cameras. Also, other studies show that the thread of boxes without cameras can affect traffic safety.

Using regression and rang correlation analyses, it was tried to find the optimal circumstances of camera locations.

  • The smaller the distance between automated cameras in Flanders, the more effective they are for injury accidents. Hence, it is proposed as a policy rule not to work with isolated cameras, but with axes of cameras close enough to each another.
  • It is found internationally that speed cameras are more effective on roads with an accident rate above average in the pre-period. This result is not found in Flanders.
  • No indication is found that cameras become less effective the longer the post-period. Hence, they are a permanent effective measure. On the other hand, no indication is found that they should become more effective with increasing post-period.

For one police zone, analyses are performed on the level of intersections instead of roads. Two data sets were available, each with their own limitations. One data set had a larger comparison group drawn from the local database, with limited information on the exact locations of accidents. A second data set, with a smaller comparison group, was based on the written warrants, where precise information was found concerning the exact location of the accident. The results of both analyses contradicted one another. Hence, no policy conclusion could be drawn from this. Except the need of uniform detailed databases.

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The Policy Research Centre for Traffic Safety carries out policy relevant scientific research under the authority of the Flemish Government. The Centre is the result of a

cooperation between Hasselt University, KU Leuven and VITO, the Flemish Institute for Technological Research.


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