Speed traps

Speed limit enforcement is the effort made by appropriately empowered authorities to improve driver compliance with speed limits. Methods used include roadside speed traps set up and operated by the police and automated roadside 'speed camera' systems, which may incorporate the use of an automatic number plate recognition system. Traditionally, police officers used stopwatches to measure the time taken for a vehicle to cover a known distance. More recently, radar guns and automated in-vehicle systems have come into use.

The perception that speed limits in a given location are being set and enforced primarily to collect revenue rather than improve traffic safety has led to controversy.

Traffic calming was built into the 1865 Locomotive Act in the UK, which set a speed limit of 2 miles per hour (3.2 km/h) in towns and 4 miles per hour (6.4 km/h) out of town, by requiring a man with a red flag to walk 60 yards (55 m) ahead of qualifying powered vehicles. The distance ahead of the pedestrian crew member was reduced to 20 yards (18 m) in 1878 and the vehicles were required to stop on the sight of a horse. The speed limit was effectively redundant as vehicle speeds could not exceed the speed at which a person could walk.

By 1895 some drivers of early lightweight steam-powered autocars assumed that these would be legally classed as a horseless carriage and would therefore be exempt from the need for a preceding pedestrian. A test case was brought by motoring pioneer John Henry Knight, who was subsequently convicted with using a locomotive without a licence. The Locomotives on Highways Act 1896 lifted some of the restrictions introduced by the 1865 Act, notably raising the speed limit for "light locomotives" under 3 tonnes to 14 miles per hour (23 km/h). The speed limit was lifted again by the Motor Car Act 1903 to 20 miles per hour (32 km/h).

A Royal Commission on motorcars in the UK reported in 1907 and raised concerns about the manner in which speed traps were being used to raise revenue in rural areas rather than being used to protect lives in towns. In parliamentary debates at the time it was observed that "Policemen are not stationed in the villages where there are people about who might be in danger, but are hidden in hedges or ditches by the side of the most open roads in the country" and were "manifestly absurd as a protection to the public, and they are used in many counties merely as a means of extracting money from the passing traveller in a way which reminds one of the highwaymen of the Middle Ages".

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Wikipedia