The findings of this study are based primarily on the systematic results from 22 local highway authorities, which consider the before and after casualty or collision records at 408 locations treated in 2004/05. Collectively these schemes cost about £16.6 million to build, which is about 15% of the local safety scheme expenditure by local authorities in England (outside London) recorded for 2004/05.
These 408 schemes together definitely (i.e. with more than 99.9% confidence) reduced both the total number of road casualties and the combined number of road deaths and serious injuries at the locations treated at a rate greater than the general national casualty reduction. The information submitted by local authorities for the 408 schemes was a mixture of casualty-based and collision-based data. This depended on how individual authorities assessed their schemes.