Speed and safety: evidence from published data

For a number of years there has been considerable interest in the relationship between speed and crashes, and in the most effective way of encouraging drivers to comply with the posted speed limit. The ultimate aim of any road safety policy must be to improve safety. Part of the improvement will be achieved through increases in compliance.

This paper brings together a number of different sources within Department for Transport and Ministry of Justice data. It begins to set out a compelling story that over the last few years, compliance with the 30 mph limit has improved, casualties have fallen, and the number of drivers receiving penalty points has also reduced.

Key findings
• There has been a large variation in the number of speed limit offences committed by motorists over recent years in England and Wales. These offences include all findings
of guilty at all courts, fixed penalty notices and written warnings in England and Wales.

• The number of offences per year started to increase from about 300,000 before 1985 to 680,000 in 1995, 1,001,000 in 1999 and 2,041,000 in 2003. Then, from a peak of 2,087,000 in 2005, the number of offences fell rapidly to 1,270,000 in 2009, the most recent data available.

• Some will attribute this fall to motorists using global positioning systems (GPS) and maps to warn them of the location of speed enforcement cameras, but the free flow speed data reviewed below shows that, particularly in urban areas, at least some of the reduction in speed limit offences is the result of better speed compliance. Another possible contributor is the introduction of speed awareness courses as an alternative to penalties.