To ask the Minister of State, Department for Transport what assessment his Department has made of the effect on traffic volume of the introduction of speed bumps in residential roads of less than 200 metres in length. (306015)

The Department for Transport has commissioned various research projects into the effectiveness of road humps. These considered the effect on traffic flow but did not include the length of the road as a factor. While results for the different types of hump varied, the research found an average flow reduction of 20 per cent. can be expected through the traffic calmed area after the installation of road humps.