【车速限制执法】
测速相机
为提高司机对车速限制的遵守程度，当局在大多数公共道路上强制执行限速。使用的方法包括由警察在路边测速(如使用雷达枪)和路边科技执法系统，这些系统可能会结合自动车牌识别系统。传统上，警察使用秒表来测量车辆行驶已知距离所需的时间。而近年，雷达枪和车载系统开始被使用。
一项包括全球的研究发现，测速相机令致命及严重伤害事故数量减少了 11% 至 44%。英国交通部估计，测速相机使有人受伤的事故减少了 22%，而在摄像头附近意外重伤或死亡的人数减少了 42% 。英国医学期刊最近报导称，测速相机可以有效减少附近的事故和伤害，并建议更广泛地安装。一项2017 年伦敦政治经济学院的研究提出：「在英国道路上再安装 1,000 个摄像头每年可以挽救多达 190 条生命，减少多达 1,130 起碰撞事故并减轻 330 起重伤。」
== 历史 ==
限速的使用早于机动车的发明和执法。面对汽车的发明，许多国家制定了车速限制法律，并采取了合适的方法去执法。英国的机车法案设置了针对车辆的速度限制，并于后来规定了执法方法。 1861 年通过的第一个机车法案将在无人居住的地区的速度限制设为10英里每小时（16公里每小时)，而在城镇内则为5英里每小时（8公里每小时)以及制定了对违法行为的罚款金额。
Stricter regulations came in the 1865 Locomotive Act, which set a speed limit of km/h in towns and km/h out of town. The act required a man with a red flag to walk m ahead of qualifying powered vehicles. The distance ahead of the pedestrian crew member was reduced to yards 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 of 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 km/h. The speed limit was lifted again by the Motor Car Act 1903 to 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".
In 1905 The Automobile Association was formed to help motorists avoid police speed traps. Chief Justice, Lord Alverston brought a test court case in 1910 ('Betts -v- Stevens') against an Automobile Association patrolman and a potentially speeding motorist—the judge ruled that where a patrolman signals to a speeding driver to slow down and thereby avoid a speed trap, that person would have committed the offence of "obstructing an officer in the course of his duty" under the Prevention of Crimes Amendment Act 1885. Subsequently, the organisation developed a coded warning system which was used until the 1960s whereby a patrolman would always salute the driver of a passing car that displayed a visible AA badge unless there was a speed trap nearby, on the understanding that their officers could not be prosecuted for failing to salute.
Gatsometer BV, founded in 1958 by rally driver Maurice Gatsonides, produced the 'Gatsometer' which was described as "a revolutionary speed-measuring device". Developed initially for improving his race times,date=April 2010 it was later marketed as police speed enforcement tool.  Gatsometer claim to have developed the first radar for use with road traffic in 1971, but this claim is undermined by evidence that radar detectors were already for sale in 1967. Gatsometer BV produced the world's first mobile speed traffic camera in 1982.
VASCAR was in use in North Carolina, New York and Indiana by February 1968.
Kevin Richardson proposed the idea of rewarding drivers travelling at or below the posted limit with a cash lottery, funded by the fines on speeding drivers. This was demonstrated in Stockholm, Sweden, in November 2010.