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Speed limit enforcement

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Title: Speed limit enforcement  
Author: World Heritage Encyclopedia
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Subject: National Maximum Speed Law, Traffic law, Traffic enforcement camera, Unenforced law, LIDAR speed gun
Collection: Law Enforcement, Road Safety, Road Speed Limit, Road Traffic Management, Speed Cameras, Traffic Law
Publisher: World Heritage Encyclopedia

Speed limit enforcement

Gatso speed camera

Speed limit enforcement is the action taken by appropriately empowered authorities to check that road vehicles are complying with the speed limit in force on roads and highways. 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, the police would have used stopwatches to measure the time taken for a vehicle to cover a known distance, but more recently, they have had speed guns and automated in-vehicle systems at their disposal.

Many jurisdictions operate traffic violations reciprocity where non-resident drivers are treated like residents when they are stopped for a traffic offense that occurs in another jurisdiction. They also ensure that penalties such as demerit points and the ensuing increase in insurance premiums follow the driver home. The general principle of such interstate, inter-provincial, and/or international compacts is to guarantee the rule 'one license, one record.'

Some groups, such as the National Motorists Association in the United States, and Motorists Against Detection in the UK claim that systems are used primarily as a source of revenue rather than to enforce traffic rules for the declared objectives. However, a meta-analysis of studies finds automated ticketing machines that enforce speed limits may have reduced the number of traffic injuries and deaths.[1]


  • History 1
  • Methods 2
    • Average speed measurement 2.1
    • Instantaneous speed measurement 2.2
    • Pacing 2.3
    • Other 2.4
  • Evidence gathering 3
  • Avoidance and evasion 4
  • Lottery 5
  • Tolerances 6
  • Law enforcement approaches 7
  • Extra-judicial enforcement 8
    • Photo-enforcement employee deaths 8.1
    • Reprisal attacks on equipment 8.2
  • Regional issues 9
    • Australia 9.1
      • New South Wales 9.1.1
      • South Australia 9.1.2
      • Victoria 9.1.3
    • Canada 9.2
    • United Kingdom 9.3
    • United States 9.4
    • France 9.5
    • Switzerland 9.6
    • Germany 9.7
    • Italy 9.8
    • Netherlands 9.9
  • See also 10
  • References 11
  • External links 12


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.[2] 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.[3] 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".[4][5]

In 1905

External links

  1. ^ Wilson C, Willis C, Hendrikz JK, Le Brocque R, Bellamy N; Willis; Hendrikz; Le Brocque; Bellamy (2010). "Speed cameras for the prevention of road traffic injuries and deaths". Cochrane Database of Systematic Reviews 2010 (11): CD004607.  
  2. ^ "MVRUS – Legislation: A summary of important legislation". UK Department of the Environment. 
  3. ^ Wey River "History of Farnham". Retrieved 26 April 2010. 
  4. ^ "Debate on the Royal Commission on Motor Cars". Hansard. 24 May 1906. Retrieved 17 April 2010. 
  5. ^ "MOTOR CAR LEGISLATION". Hansard. 16 July 1907. Retrieved 17 April 2010. I regard the abolition of the speed limit as the most important recommendation of the Royal Commission... 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... I am entirely in sympathy with what the noble Earl said with regard to police traps. In my opinion they are 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. 
  6. ^ "About us". The AA. Retrieved 26 February 2010. 
  7. ^ JA Coutts, 'Obstructing the Police' (1956) 19 MLR 411
  8. ^ "Road Traffic – 1900– 1929". Retrieved 27 February 2010. 
  9. ^ Massey, Ray (4 February 2010). "Drivers face breakdown nightmare after AA staff ballot for first strike in 105 years". Daily Mail (London). 
  10. ^ a b c d "History". Gatsometer. Retrieved 18 April 2010. 
  11. ^ "Radar Speed Trap Warning Apparatus (Licence)". Hansard. 2 March 1967. Retrieved 25 April 2010. a pocket-sized instrument is being produced by Marchant House Limited of New Street, Oadby, Liecester, to be used in motor vehicles to give instant warning of a police radar speed trap ... Anyone wishing to use this type of apparatus would require a licence under the Wireless Telegraphy Act, 1949. The firm in question has recently been informed that I am not prepared to issue a licence for such purposes 
  12. ^ "The Highway: Versatile VASCAR". Time. 9 February 1968. 
  13. ^ "Specs spies on speeding motorists". BBC News. 14 July 2005. Retrieved 31 May 2008. 
  14. ^ Brian Bell (2001). Insight Guide: French Riviera. Langenscheidt Publishers. p. 318.  
  15. ^ CVC 40802 Speed Traps, CVC 40801 Speed Trap Prohibition
  16. ^ US 5521696 
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  18. ^ Police Technology (Pearson Prentice Hall) 2004: 15. 2004.  
  19. ^ Alan Buckingham (17 October 2003). "Speed Traps: Saving Lives or Raising Revenue?". Retrieved 27 April 2010. 
  20. ^ "Gatso Photo Checking". Association of British Drivers. Retrieved 26 April 2010. 
  21. ^ Max Cameron (10 June 2008). Development of Strategies for Best Practice in Speed Enforcement in Western Australia (Report). Monash University Accident Research Centre. p. 6.
  22. ^ "Radar detectors FAQ". Whistler Group. Retrieved 17 September 2010. 
  23. ^ "Driver upset after ticketed for flashing headlights".  
  24. ^ Bloomfield, Steve (26 June 2005). "AA causes fury by publishing its first-ever map of speed cameras". The Independent (London). Retrieved 17 April 2010. A controversial decision by the AA to publish its first map of speed traps has provoked a storm of protest from safety experts, who accuse the organisation of encouraging motorists to break the law. 
  25. ^ Sharkey, Joe (4 May 2008), "The Camera That Wears a Badge", New York Times, retrieved 7 July 2011 
  26. ^ Schultz, Jonathan (30 November 2010). "Speed Camera Lottery Wins VW Fun Theory Contest". The New York Times. 
  27. ^ "PA Vehicle Code Chapter 75 § 3368(c)". 
  28. ^ Day, M. V.; Ross, M. (2011). "The value of remorse: How drivers' responses to police predict fines for speeding". Law and Human Behavior 35 (3): 221–234.  
  29. ^ "Speed Enforcement". CPS. Retrieved 3 February 2014. 
  30. ^ "Toleranzabzüge bei standardisierten Messverfahren zur Feststellung von Geschwindigkeitsverstößen". (in Deutsch). Retrieved 5 December 2014. 
  31. ^ "Geschwindigkeitsüberschreitung". (in Deutsch). Retrieved 5 December 2014. 
  32. ^ a b Alexandra Smith (31 March 2011). "Greater Leeway for Speeding Drivers". The Age (Australia). Retrieved 16 June 2011. 
  33. ^ "Making travel safer: Victoria's speed enforcement program".  
  34. ^ S.P. Hardy. "Inaccurate Speedos". Retrieved 28 April 2010. 
  35. ^ "AASHTO Policy Resolution: The National Statutory Speed Limit". American Association of State Transport Highway Officials. 19 April 1994. Retrieved 17 September 2009. 
  36. ^ Organisation for Economic Co-operation and Development, European Conference of Ministers of Transport, OECD/ECMT Transport Research Centre (2006). Speed Management. OECD Publishing. p. 155.  
  37. ^ Robert Lemos (2 July 2001). "State Puts Brakes on GPS Speeding Fines". CNET. Retrieved 29 April 2010. 
  38. ^ Amy D. Propen (10 June 2006). "Critical GPS: Toward a New Politics of Location". Department of Rhetoric, University of Minnesota. 
  39. ^ Davenport, Paul (20 April 2009). "Photo-Radar Van Driver Shot to Death". Retrieved 19 January 2014. 
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  41. ^ Stern, Ray (1 December 2008). "Local Photo Enforcement Vandalism is Child's Play Compared to Destruction of Speed Cameras Elsewhere – Phoenix News – Valley Fever". Retrieved 24 May 2012. 
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  43. ^ "NSW Speed Cameras in Doubt". The Age (Melbourne). 10 August 2005. Retrieved 28 April 2010. 
  44. ^ a b c Cash cow' speed cameras raise $350m"'". The Sydney Morning Herald (Fairfax Media). 2 June 2011. Retrieved 27 June 2011. 
  45. ^ Report finds speed cameras are an effective safety tool Media Release The Hon Duncan Gay MLC Minister for Roads and Ports 27 July 2011
  46. ^ NSW Government switches off 38 speed cameras Caradvice 27 July 2011 (includes locations of cameras turned off)
  47. ^ a b "PARLIAMENT is facing a renewed push for a top-level inquiry into the use of speed cameras". Adelaide Now (News Limited). 27 June 2011. Retrieved 27 June 2011. 
  48. ^ "Victoria's speed camera saga continues". The 7.30 Report. Australian Broadcasting Corporation. Retrieved 7 June 2011. 
  49. ^ "Government acts on fixed speed cameras". Media Release 14 May 2004. Office of the Premier. Retrieved 7 June 2011. 
  50. ^ a b Dowling, Jason (1 January 2009). "State's road toll dips to its lowest on record". The Age (Melbourne). 
  51. ^ a b Sexton, Reid (27 December 2009). "Victoria's road toll at record low". The Age (Melbourne). 
  52. ^ "A-G to probe use and integrity of road cameras". The Age (Australia: Fairfax Media). 25 May 2011. Retrieved 14 June 2011. 
  53. ^ "As road toll jumps, police urge caution". The Sydney Morning Herald (Fairfax Media). 10 June 2011. Retrieved 14 June 2011. 
  54. ^ "Speeding and disobedient drivers deliver a windfall for government coffers". The Herald Sun (Herald and Weekly Times). 11 June 2011. Retrieved 19 June 2011. 
  55. ^ Edmonton, The (19 February 2006). "Charges won't halt photo radar". Retrieved 24 May 2012. 
  56. ^ Wittmeier, B. "Police set sights on super speeders". Edmonton Journal. Retrieved 3 June 2014. 
  57. ^ "Lack of police funds could end South West speed cameras". BBC News. 22 July 2010. 
  58. ^ "Speed cameras will stay – but no more maintenance | News". This is Gloucestershire. 3 August 2010. Retrieved 24 May 2012. 
  59. ^ "Speed camera turn-off starts – Mirror Online". Daily Mirror. 2 August 2010. Retrieved 24 May 2012. 
  60. ^ "Town ditches fixed speed cameras". BBC News. 31 July 2009. 
  61. ^ a b Barrett, David (7 August 2010). "Speed camera switch-off sees fewer accidents". The Daily Telegraph (London). 
  62. ^ "O'Halloran and Francis v. The United Kingdom". 
  63. ^ "Section 21, traffic officer numbers reduction in the UK". UK Parliamentary publications. 
  64. ^ "page 147 Transport statistics 2009 edition". Department for Transport UK. 
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  66. ^ "Plan to return Oxfordshire's speed cameras". BBC News. 2 November 2010. 
  67. ^ "Speeding fine numbers double with cameras back on". BBC News. 5 May 2011. 
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  71. ^ Humphrey, Tom. "Speed cameras catch police chief's interest » Knoxville News Sentinel". Retrieved 24 May 2012. 
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  73. ^ study of speed cameras
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  76. ^ "Speed cameras on U.S. highways?". CNN. 4 June 2009. Retrieved 5 June 2009. 
  77. ^ San Diego Court Ruling, 2001.
  78. ^ US Department Of Transportation Federal Highway Administration – Traffic Enforcement Camera Regulations, 9 December th 2008.
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  83. ^ "No details yet for end to state's photo radar". Retrieved 24 May 2012. 
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  86. ^ "Carte des radars fixes et automatiques en France". Retrieved 24 May 2012. 
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See also

In the Netherlands, red light cameras are often combined with speed cameras in the same unit.


In Italy, the fixed speed cameras on motorways and highways are announced with a sign about 400 meters before: Controllo elettronico della velocità, and marked in Italian road maps.[88][89]


In Germany, radar detectors are prohibited, however, current mobile controls are mentioned by some radio stations, which is not illegal.


In Switzerland, it is strictly forbidden to announce speed controls.[87] If the software of navigation equipment includes the locations of fixed speed cameras, the devices can be seized and destroyed. This also applies to mobile phones or handheld devices with the appropriate function.


In France, the fixed speed cameras on motorways are announced with a sign about half to 2 km before: Pour votre sécurité, contrôles automatiques (For your safety, automatic controls) and marked in French motorway maps.[86] On non-motorway roads, sometimes there is a sign however in other locations an electronic sign showing your speed may indicate a fixed speed camera further along the road. Average speed cameras now operate in some areas.


It has been announced that Arizona will not renew its contract with Redflex, the company that operates the cameras.[83] However, many towns in Arizona (e.g. Chandler, Mesa, Scottsdale, Paradise Valley, Superior) still have red light and/or speed cameras. Photo enforcement is illegal in the town of Gilbert, Arizona. Tempe, Arizona has removed all of their red light cameras. Baker, Louisiana still contracts with Redflex.[84] This association is the subject of legislative action.[85]

Opposition groups have formed in some locations where automated traffic enforcement has been used. In the US city of Scottsdale Arizona, an activist group CameraFraud was formed and staged sign-wave protests and petition drives to oppose the use of speed limit enforcement cameras ('photo radar').[79][80][81] In the 2008 elections in nearby Pinal County, Paul Babeau won an election for Sheriff after making a campaign promise to eliminate speed cameras.[82]

In the United States, it is common for all installation, operation, and verification procedures to be carried out by private companies that in some States receive payment based on the number of infringements they issue, and often under no testing regime whatsoever,[77] however these units are required by law to take at least two pictures of each vehicle.[78]

As of 2009, speed cameras existed in 48 communities in the United States, including in Arizona, Colorado, Illinois, Iowa, Louisiana, Maryland, Massachusetts, New Mexico, Ohio, Oregon, Tennessee, Washington, and Washington, D.C.[76]

As of late 2008, cameras were placed along all Phoenix area freeways capturing drivers doing speeds greater than 11 mph over the posted speed limit. Over 100 new cameras were expected to be up and running by 2009.[74][75]

A 2007 study of speed cameras on the Arizona State Route 101 in Scottsdale found a 50% reduction in the total crash frequency, with injuries falling by 40% however rear-end collisions increased by 55%.[73]

Some U.S. states that formerly allowed red-light enforcement cameras but not speed limit enforcement cameras ('photo radar'), have now approved, or are considering, the implementation of speed limit enforcement cameras. The Maryland legislature approved such a program in January 2006. In 2005, 2006, 2008 and 2009 the California legislature considered, but did not pass, bills to implement speed limit enforcement cameras.[70] Tennessee legislators are also considering expanding their speed limit enforcement cameras after successes in Chattanooga such as generating $158,811 in revenue in the first three months.[71][72]

Speed camera in Mount Rainier, Maryland catching a station wagon speeding on US 1
Speed camera in Mount Rainier, Maryland catching a station wagon speeding on US 1
Two images from a speed enforcement camera in Mount Rainier, Maryland, documenting a vehicle alleged to be traveling 50 mph in a 25 mph zone.

Initially, Illinois used photo enforcement for construction zones only. There was legislation on the books to expand that throughout the state. However, Chicago has expanded its red light camera program and is planning to put speed cameras in school zones. Some suburbs (e.g. Alsip) already have cameras at various intersections.

Patagonia, Arizona has been cited on the National Motorists Association’s website [1] as having one of the nation’s most active speed traps. City police regularly conceal their patrol cars behind trees along Arizona Highway 82 where motorists enter the city’s outskirts. The legal speed limit drops in a short space from 55 mph to 30 mph leading to some drivers who are not alert being caught. The minimum fine for exceeding the posted speed limit even by 1 mph is $146.

In the U.S. state of Ohio, the issue of whether a city has jurisdiction under the Ohio Constitution to issue citations based on speed cameras was heard by the Ohio Supreme Court on 18 September 2007, in the case of Kelly Mendenhall et al. v. The City of Akron et al.[68][69] The court ruled in favor of Kelly Mendenhall.

United States

The number of designated traffic officers fell from 15–20% of Police force strength in 1966 to seven per cent of force strength in 1998, and between 1999 and 2004 by 21%.[63] It is an item of debate whether the reduction in traffic accidents per 100 million miles driven over this time[64] has been due to robotic enforcement. In the seven-month period following speed cameras in Oxfordshire being switched off in August 2010, fatalities increased from 12 to 18, a figure not out of line with the variation in fatalities over a ten-year period.[65] Plans had been made to switch the cameras back on by November 2010, on the basis of increased speeds at camera sites,[66] which occurred in April 2011.[67] Oxfordshire had followed the lead of Swindon, which encountered a decline in casualties, serious injuries, and fatalities.[61]

There has also been debate as to whether the use of such cameras in order to force a driver to confess to the crime of speeding is in violation of European basic human rights; however, in 2007 the European Court of Human Rights, in O’Halloran and Francis v United Kingdom, found there was no breach of article 6 of the Human Rights Act 1998 in requiring the keepers of cars caught speeding on camera to provide the name of the driver, or to be subject to criminal penalty of an equivalent degree of severity if they failed to do so.[62]

The United Kingdom uses a variety of methods to enforce its road speed limits including average and instantaneous speed cameras, however eight counties are to switch off or remove cameras and a further two counties are considering such action.[57][58][59][60][61]

United Kingdom

In September 2012, Edmonton police chief Rod Knecht proposed that "excessive speeders" should have their vehicles seized and impounded, after a rash of high speeding drivers were charged, the speed limit.overmany driving 50 - 100km/hr [56]

In February 2006, Edmonton, Alberta, Canada erupted in scandal when it was alleged that two police officers accepted bribes from private contractors who received lucrative contracts to provide speed limit enforcement cameras. The officers and contractor involved now face criminal charges that remain before the courts.[55]

Speed limit enforcement cameras were a substantial election issue in the provinces of Ontario and British Columbia, and were abolished by Premiers Mike Harris in 1995 and Gordon Campbell in 2001.


The Victoria government forecasts that a revenue of A$245 million will be raised from fines levied on drivers breaking Victorian road rules, a large proportion being from speed limit enforcement, in 2011.[54]

In June 2011, in Victoria, the road toll for the year so far was reported to be "significantly higher"" than it was for the same period of the previous year.[53]

After growing numbers of complaints about incorrect and inappropriate fines, Victoria's Auditor-General plans to investigate whether speed cameras are being used primarily to raise revenue for the state government rather than to improve road safety.[52]

Victoria achieved record low road tolls in both 2008 and 2009.[50][51] Newspaper reports credited a co-ordinated and well-funded campaign that focused on higher risk young drivers, more aggressive policing, increased police activity, drink driving, and in 2009, a 50% increase in the use of mobile speed cameras.[50][51]

In 2004, in a Poltech fixed speed camera on Melbourne's Western Ring Road recorded a four cylinder Datsun 120Y sedan travelling at 158 km/h, but testing found this vehicle only capable of 117 km/h.[48] A Victorian state government inquiry found that maintenance and accuracy checks had not been done regularly.[49]

Gatso Mobile Speed Camera, used in Victoria, Australia. The camera is mounted on the passenger side dash, whilst the black box on the front is the radar unit.


It is predicted that the South Australia (SA) government will raise A$138 million in the 2011–12 year from speed limit enforcement activities. They raised A$114 million in 2010–11.[47] The SA government are resisting moves by their opposition to commission an inquiry into whether speed cameras are being used effectively and efficiently: to improve road safety, to raise revenue, or both.[47]

South Australia

In June 2011, the New South Wales (NSW) government was reported to have raised A$350 million over the previous five years from speed cameras.[44] The Roads Minister accused the previous Labor government of using speed cameras to raise revenue;[44] the Auditor-General was therefore tasked with investigating all 141 fixed speed cameras in use throughout the state.[44] Following the release of the report, 38 speed cameras, located primarily on highways, were switched off after the Auditor-General determined that they had no significant road safety benefit. The report found the majority of fixed speed cameras had a proven road safety benefit. The report also concluded that it was "too early" to conclude if mobile speed cameras had an impact on road safety, although early results indicated drivers might be speeding less. To address public concerns, the RTA would now monitor the effectiveness of individual fixed speed cameras annually.[45][46]

In August 2005, in Sydney, Australia a speed camera photograph was challenged on the basis that an MD5 cryptographic hash function used to protect the digital photograph from tampering was not robust enough to guarantee that it had not been altered. Magistrate Lawrence Lawson demanded that the Roads and Traffic Authority (RTA) produce an expert witness who could prove the photographs were tamper-proof, but the RTA was unable to provide such evidence. The defendant was acquitted and awarded court costs.[43]

New South Wales


Regional issues

Retribution attacks on photo enforcement equipment have become commonplace throughout the world.[40][41][42]

Reprisal attacks on equipment

Doug Georgianni, 51, was shot as he operated a photo radar van on a Phoenix freeway and later died at a hospital.[39]

Photo-enforcement employee deaths

In 2001, Acme-Rent-a-Car in Connecticut controversially tried to use a contractual clause in the rental agreement to issue speeding fines to any of its customers that exceeded speed limits as detected by GPS tracking units its cars. The company actions were challenged and defeated in court.[37][38]

Extra-judicial enforcement

Authorities are not able to monitor every vehicle on every road—limited resources generally mean that enforcement needs to be targeted. A New Zealand study concluded that actual enforcement as well as the perceived chance of being caught both contributed to changes in drivers' behaviour.[36]

Local conditions, law and police practices mean that the tactics adopted to catch speeding motorists vary considerably. In some regions, police may adopt a more subtle approach, concealing themselves and their equipment as much as possible; other jurisdictions require highly visible policing, with cameras painted yellow, and camera operators not permitted to use approaches such as attaching the camera to what may appear to be a broken-down vehicle when enforcing speed limits.

Law enforcement approaches

In some areas of the United States, drivers are expected to travel 5-10 miles under the legal speed limit when the temperature is below freezing. Even if road conditions are perfectly fine, a motorist can still be fined for operating their vehicle too fast for roads that could be dangerous if the weather was worse.

In Mexico, maximum speed limit is set as 80 kilometres per hour (50 mph) on urban freeways, 50 kilometres per hour (31 mph) or 60 kilometres per hour (37 mph) on avenues, 40 kilometres per hour (25 mph) on streets, and 10 kilometres per hour (6.2 mph) or 20 kilometres per hour (12 mph) around schools depending on jurisdiction. However, fines are only given when speeding above 90 kilometres per hour (56 mph), thus giving a 10 kilometres per hour (6.2 mph) tolerance. The Mexican highway patrol (Mexico City) and traffic law enforcement officers (Guadalajara) may enforce speed laws only when a car is speeding above reasonable speeds in regard of the amount of traffic. Maximum speed for all Mexican highways is 110 kilometres per hour (68 mph). Speeding fines are given to those going 130 kilometres per hour (81 mph) and up to 220 kilometres per hour (140 mph). Police may however place a squad car as a pace car so drivers behind cannot exceed 100 kilometres per hour (62 mph); this is common during Summer and Winter holiday season.

Speed limit policy can affect enforcement. According to a 1994 report by the AASHTO, "experience has shown that speed limits set arbitrarily below the reasonable and prudent speed perceived by the public are difficult to enforce, produce noncompliance, encourage disrespect for the law, create unnecessary antagonism toward law enforcement officers, and divert traffic to lesser routes".[35]

The state of Victoria in Australia allows for only a 3 kilometres per hour (1.9 mph) tolerance for mobile speed cameras and 2 kilometres per hour (1.2 mph) for fixed cameras on the basis that although the increased risk is lower there are very many more drivers involved which creates a substantial risk across the road network.[32][33] An alternate view is that police devices are accurate to 1 km/h, and that a 2–3 km/h tolerance is the minimum margin that police require to defeat any challenge in court regarding the accuracy of their speed measurement equipment.[34] Speed tolerance in New South Wales was an election issue in 2011, following a move by the budget committee of the previous Labor state government to abolish the 3 km/h margin in order to increase revenue.[32]

In Germany, at least a 3 km/h tolerance (3% of measured speed when speeding over 100 km/h) in favor of the offender is always deducted. This tolerance can increase up to 20% depending on the method of measurement.[30] Fines for speeding depend on how high above the speed limit the measured speed is and where the offense occurred. Speeding in built-up areas invariably carries higher fines than outside city limits. While fines for minor offenses tend to be moderate, speeds in excess of 20 km/h (12 mph) above the limit in built-up areas result in distinctly higher fines and points on the driver's license, and depending on the speed at which the offender was clocked, may lead to a driving ban of at least one month.[31]

As older vehicle construction regulations allowed a speedometer accuracy of +/- 10%, in the United Kingdom ACPO guidelines recommend a tolerance level of the speed limit "+10% +2 mph" (e.g., a maximum tolerance in a 30 mph (50 km/h) zone of 30 + (30 × 10% = 3) + 2 = 35 mph).[29]

A study of over 1000 drivers caught speeding in the U.S. and in Canada examined factors that predicted fines issued by police officers. In both countries, drivers were stopped for speeding on average 15-17 mph over the speed limit and received fines of approximately $141–$148. As expected, drivers travelling at higher speeds over the limit received higher fines. What drivers said to the police also affected the amount of the fine. Forty-six percent of American and Canadian drivers reported offering an excuse (e.g. "I didn't realize the speed I was driving"), which was the most common type of verbal response. Excuses, justifications, and denials did not reduce the amount of the fine. Almost 30% of drivers expressed remorse (e.g., "I'm sorry") and received a considerable reduction in fines. Offers of remorse were most effective at higher speeds over the limit. For example, American speeders who offered remorse for traveling at higher speeds over the limit (21 mph) received fines that were $49 lower than drivers speeding the same amount, but who did not say they were sorry. Although this research indicated that apologies can be related to lower fines for speeding, most drivers who offered remorse did not get off scot-free, as they still received tickets. To maintain a relatively normal sample of speeders, a small percentage of drivers who reported extreme speeds (50 mph or more over the limit) or very severe fines ($500 or more) were excluded. Therefore, these findings do not suggest that extreme speeders, even remorseful ones, would receive lenient treatment from police officers.[28]

Speed limits may not be enforced for speeds close to the legal limit. In the United States, speeding enforcement tolerance is usually up to the discretion of the arresting officer. Some states (such as Pennsylvania and Florida) have official tolerances.[27]


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.[26]


Mobile applications such as Njection, Trapster, and Waze provide mobile information to drivers on speed traps and traffic conditions. These applications rely on users to keep the databases current.[25] In addition to mobile applications that might be considered evasion centric, there are other similar mobile applications that are classified as Intelligent speed adaptation technologies that are considered to compliance centric and in Australia both National and State Road Safety Strategies encourage the adoption of such technologies.

In 2006, the UK Automobile Association controversially published a road map that included the location for thousands of speed cameras—the first time such information was available in printed form,[24] although more accurate and frequently updated GPS-based information was freely available for some time before that.

Drivers may flash their lights to approaching drivers to warn them of a speed trap. The legal standing of this action also varies by jurisdiction. In the United States, it is common for motorists with Citizen's Band (CB) radios to report the location of speed traps over the CB radio to other motorists.[23]

Some drivers use passive radar detectors or LIDAR detectors to detect police radar or LIDAR signals, with the intention of avoiding or evading prosecution by slowing down before entering an enforcement zone. The legal standing of these type of devices varies by jurisdiction. For example, they are legal in most of the United States, but not in most of Canada.[22] Active devices might also be used—in this instance, radar or LIDAR signals are typically jammed with counter emissions. These devices are more frequently illegal than passive devices.

Passive RADAR and LIDAR detector

Avoidance and evasion

Types of camera include Gatso, Truvelo Combi and D-cam.

The change from analogue "wet film" to digital technology has revolutionised speed cameras, particularly their maintenance and the back-office processing required to issue penalty notices. Images from digital cameras can be uploaded in seconds to a remote office over a network link, while optical character recognition software can automate the "reading" of vehicle registration numbers.[21]

Photographs are typically time-stamped by a high resolution timing device so that a vehicle's speed can be checked manually after the fact if necessary using the secondary method of calculating its speed between a series of calibrated lines (known as "Dragon's Teeth") painted on the road surface.[20]

While digital cameras can be used as the primary means of speed detection when combined with automatic number plate recognition (ANPR) average-speed camera systems, their use is more commonly restricted to evidence gathering where speeding offences are detected by various other types of sensors such as Doppler radar, piezo strips, infrared or laser devices.

UK fixed speed camera with road calibration markings

Evidence gathering

Some jurisdictions such as Australia, allow prosecutions based on a subjective speed assessment by a police officer.[19] In the future there is the potential to track speed limit compliance via GPS black boxes for recidivist speeders identified in the Australian National Road Safety Strategy 2011 - 2020 section on Intelligent speed adaptation


Officers in some jurisdictions may also use pacing, particularly where a more convenient radar speed measuring device is not available—a police vehicle's speed is matched to that of a target vehicle, and the calibrated speedometer of the patrol car used to infer the other vehicle's speed.[18]


Instantaneous speed cameras measure the speed at a single point. These may either be a semi-permanent fixture or be established on a temporary basis. A variety of technologies can be used:

Traffic Speed Interceptor - Vehicles with speed camera used by Bangalore Police, India
Automatic traffic speed measurement in Denmark

Instantaneous speed measurement

Speed enforcement using average speed measurement is expressly prohibited in California.[15]

Police in some countries like France have been known to prosecute drivers for speeding, using an average speed calculated from timestamps on toll road tickets.[14]

Automatic number plate recognition (ANPR) systems that use a form of optical character recognition read the vehicle's licence or registration plate. A computer system reads vehicle registration plates at two or more fixed points along a road, usually hundreds of meters or even kilometers apart, then uses the known distance between them to calculate a vehicle's average speed. From the mean value theorem, we know that the vehicle's speed must equal its average speed at some time between the measurements. If the average speed exceeds the speed limit, then a penalty is automatically issued.[13]

VASCAR is a device that semi-automates the timing and average speed calculation of the original manually operated "speed trap". An observer on the ground, in a vehicle or in the air simply presses a button as a vehicle passes two landmarks that are a known distance apart, typically several hundred metres.

Average speed measurement

Speed limits were originally enforced by manually timing or "clocking" vehicles travelling through "speed traps" defined between two fixed landmarks along a roadway that were a known distance apart; the vehicle's average speed was then determined by dividing the distance travelled by the time taken to travel it. Setting up a speed trap that could provide legally satisfactory evidence was usually time consuming and error prone, as it relied on its human operators.

Police officers in Bavaria checking speed with a tripod-mounted LIDAR speed gun.


VASCAR was in use in North Carolina, New York and Indiana by February 1968.[12]

Gatsometer BV, founded in 1958 by rally driver Maurice Gatsonides, produced the 'Gatsometer' which was described as "a revolutionary speed-measuring device".[10] Developed initially for improving his race times, it was later marketed as police speed enforcement tool.[10] 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.[10] Gatsometer BV produced the world's first mobile speed traffic camera in 1982.[10][11]


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