Further results from a trial comparing a hidden speed camera programme with visible camera operation.

As described in a previous paper [Accident Anal. Prev., 33 (2001) 277], the hidden camera programme was found to be associated with significant net falls in speeds, crashes and casualties both in 'speed camera areas' (specific signed sites to which camera operation is restricted) and on 100 km/h speed limit roads generally. These changes in speeds, crashes and casualties were identified in the trial area in comparison with a control area where generally highly visible speed camera enforcement continued to be used (and was used in the trial area prior to the commencement of the trial). There were initial changes in public attitudes associated with the trial that later largely reverted to pre-trial levels. Analysis of 2 years' data of the trial showed that falls in crash and casualty rates and speeds associated with the hidden camera programme were being sustained. It is not possible to separate out the effects of the concealment of the cameras from other aspects of the hidden speed camera programme, such as the four-fold increase in ticketing. This increase in speed camera tickets issued was an expected consequence of hiding the cameras and as such, an integral part of the hidden camera programme being evaluated.