Speed cameras, speed humps, speed limits, and traffic management:

Updated December 2005
Wp ref. speedc\Speed cameras 02

Background

There is a long standing belief that a high proportion of accidents are due to what is loosely termed "speeding". Data in the Traffic and Road Research laboratory's Report TRL 323 was used to support that believe in that the following were combined under the "inappropriate speed" heading.

That combined category was also associated with the stronger term "excessive speed".

In February 2004 the DfT published Road Safety Research report 43 (Review of the Contributory Factors System). In Appendix B we find 12.5% of accidents in 2001 had excessive speed as a "contributory factor" but it is clear that within the 12.5% were overlapping factors ranging from alcohol to carelessness. Further analyses, obtained by Paul Smith of Safe Speed from the Avon and Somerset and Durham Police authorities, showed that 70% of excessive speed accidents were due to speed deemed to be "inappropriate to the conditions". That left 4% of all accidents with exceeding the speed limit, here called "speeding", as a contributory factor.

Analysis and comment

Probably only a proportion, perhaps half, the 4% of the accidents where "exceeding the speed limit" was a contributory cause, should be attributed to what the general public may regard as "excessive speed" and the 2% remaining should be reduced to allow for overlapping effects of carelessness, etc.

Nevertheless, if the cameras could save half the 2% then they could be credited with a reduction of some 30 deaths or 370 KSI annually. Those numbers are substantially below the 870 estimated from the National Safety Camera Programme 4 th year report after allowing for regression to the mean.

Separately from that we note (see the tabulation and graphs below) that despite the cameras being supported by tens of thousands of speed humps, the trend in the decline of the KSI casualty rate is, if anything, less steep than previously and the decline in the death rate between the years 1999 and 2003 was very much less steep than previously. That disconnect between the national trend and the supposed benefit of the cameras undermines the notion that the cameras are saving any lives at all.

Views

For many people the cameras have (a) turned driving into a nightmare, where we concentrate on our speedometers rather than the road ahead (b) led to the unreasonable prosecution of millions and the destruction of tens of thousands of livelihoods (c) turned many law abiding people against the police.

Further the representation by the DfT and the police that speed, or excessive speed, is a major cause of accidents, has undermined the reputation for integrity of both parties.

Meanwhile speed limits are always either too high or too low depending on the time of day and traffic conditions.

Against that background we canvas for advisory speed limits backed by hidden cameras used to catch the truly dangerous, and by education campaigns promoting safe driving. In any event, few of us would want to live in a country where every infringement of an unreasonable regulation was photographed and punished.

Links www.safespeed.org.uk
www.safespeed.org.uk/pr112

DATA TABLE. Source is the Transport Statistics Great Britain

Comment: Instead of the thousands of speed cameras, supported by tens if not hundreds of thousands of speed humps leading to an acceleration in the established decline of the injury rate, that decline if any thing, flattened off.