A speed camera is a Home Office type approved device that records a vehicle's speed, with a photograph, as evidence of a speeding offence. The Department for Transport's guidance names four kinds of equipment: fixed speed cameras, mobile speed cameras, average speed cameras and red-light cameras. This guide explains how each measures, how visible it must be, how sites are chosen and what follows.
The four kinds of speed camera
The Department for Transport (DfT) set out the four types in Circular 01/2007, guidance for England and Wales published on 31 January 2007 and, on 11 October 2026, still on GOV.UK without update or withdrawal. It says when each type fits; the right-hand column adds how the police describe the measuring.
| Type | Where the guidance says it fits | How it measures |
|---|---|---|
| Fixed speed camera | Sites where collisions are clustered around one point | Radar in a roadside housing. A Gatso camera takes two rear-facing images 0.5 seconds apart; a Vector SR uses tracking radar over several lanes |
| Mobile speed camera | Sites where collisions are scattered along a road, or where enforcement is needed at set times | Laser from a marked van that measures vehicles coming towards it and going away |
| Average speed camera | Sites with collisions scattered along a length of road, and major roadworks | Linked number plate cameras time a vehicle between points |
| Red-light camera | Traffic-light junctions where collisions follow vehicles failing to stop at red | At Redspeed sites, loops under the road trigger two images; many also detect speeding |
Police Scotland also describes HADECS: a digital camera and radar system on a gantry that enforces mandatory variable speed limits.
How a speed camera measures your speed
Radar cameras work from the Doppler effect. According to the National Police Chiefs' Council (NPCC) technical guide, an across-the-road radar shines a beam at a fixed angle. A beam that meets a vehicle at an angle senses less than its true speed (the guide calls this the cosine effect), and because the angle is known, the electronics correct for it and record the speed directly. Laser units send a series of light pulses and calculate the speed from the vehicle's movement between them.
White lines on the road at some fixed sites are not the measurement. Police Scotland says they are a secondary check against the distance travelled between the two photographs; only the radar determines the speed.
An average speed system divides a measured distance by the time taken. The NPCC guide adds that the baseline is set at the minimum possible driving distance, so the system shows the lowest speed that was possible between the points. How section control works has the detail.
Section 20 of the Road Traffic Offenders Act 1988 says a record from a prescribed device is not admissible as evidence unless the device is of a type approved by the Secretary of State. Police Scotland says all its cameras are Home Office type approved and calibrated on a regular basis by a third party.
Why many speed cameras are yellow
The DfT guidance asks for fixed camera housings to be yellow: painted or sheeted front and back in lit areas, with yellow retro-reflective sheeting elsewhere. Camera housings, or the camera operator or enforcement vehicle, should be clearly visible from the driver's viewpoint at 60 metres where the limit is 40 mph or less, and at 100 metres at all other limits.
That guidance is not a condition of enforcement: the circular says non-compliance gives no mitigation or defence, and that it does not restrict the police's discretion to enforce covertly. GoSafe says a missing camera sign does not invalidate an offence.
Where speed cameras are put
Police Scotland names five criteria: a history of injury collisions, the speed profile of the road, agreement of the police and the roads authority, the enforcement strategy and an annual site review. GoSafe follows Welsh Government guidance, with cameras where speeding is a concern, near schools or at roadworks. Speed camera locations and maps covers the official maps.
What happens after a camera records you
According to GOV.UK, within 14 days of the offence you are sent a Notice of Intended Prosecution and a Section 172 notice, and you must return the Section 172 notice within 28 days to say who was driving. Section 1 of the Road Traffic Offenders Act 1988 sets that fourteen-day rule for the notice, served on the driver or the registered keeper, with exceptions in section 2.
The minimum penalty for speeding is a £100 fine and 3 penalty points. Twelve or more points within 3 years can mean disqualification, and a court can fine up to £1,000, or £2,500 on a motorway. This is a summary, not legal advice.
Speed camera apps and the law
The clearest official statement is an Ask the Police answer, produced by the Police National Legal Database (PNLD) and published on the West Yorkshire Police website. It says devices that only provide information about camera site locations are lawful in the UK, and that jammers are unlawful. It adds that abroad even these may be unlawful, so check the law where you drive. The answer is undated. Speed camera warnings by country lists the rules in the countries BlitzBuddy covers.
GOV.UK says it is illegal to hold and use a phone or sat nav while driving; a dashboard holder or windscreen mount counts as hands-free.
What BlitzBuddy does about speed cameras
BlitzBuddy gives no speed camera warnings in the UK, Ireland or any other country outside the five where it warns; your speed, trips and reports from other drivers still work. Camera warnings switch on by themselves when you arrive in the Netherlands, Belgium, Germany, France or Türkiye, with fixed cameras from OpenStreetMap, Lufop.net and public government lists.
The law there differs per country. In Germany, § 23 (1c) StVO forbids drivers to use a speed camera warner while driving; the warnings can be switched off under Profile, Warnings, and the driver is responsible. In France, article R413-15 of the Code de la route bans devices that detect or disturb the equipment used to record traffic offences, and since 5 January 2012 its paragraph V also covers devices that warn of or inform about the location of that equipment. Using these warnings is the driver's own responsibility.
More guides on the same topic are collected under speed camera guides.
Sources
- DfT Circular 01/2007: Use of speed and red-light cameras for traffic enforcement, Department for Transport (pdf)
- Using speed and red-light cameras for traffic enforcement: deployment, visibility and signing, GOV.UK (publication page of the circular)
- Camera Type, Police Scotland Safety Cameras
- About, Police Scotland Safety Cameras
- Guide for the operational use of speed and red-light offence detection technology, version 1.2.1, National Police Chiefs' Council, July 2016 (pdf, linked from National Highways)
- Road Traffic Offenders Act 1988, section 20, legislation.gov.uk
- Road Traffic Offenders Act 1988, section 1, legislation.gov.uk
- Speeding penalties, GOV.UK
- Using a phone, sat nav or other device when driving, GOV.UK
- Code de la route, article R413-15, Légifrance (in French, version in force since 5 January 2012)
- Straßenverkehrs-Ordnung, § 23, Federal Ministry of Justice (in German)
- Is it illegal to have a speed camera detector in my car?, Ask the Police (Police National Legal Database), on the West Yorkshire Police website
- Our cameras, GoSafe
- FAQs, GoSafe
- Average speed enforcement cameras around roadworks, National Highways
- Camera data in the countries where BlitzBuddy warns: © OpenStreetMap contributors
Sources read on 11 October 2026.
Frequently asked questions
Are speed cameras always yellow?
No. The Department for Transport guidance asks for yellow housings on fixed speed cameras, and National Highways paints its roadworks average speed cameras yellow. Mobile units are marked vehicles. The guidance is not a legal condition, so the limit applies whatever colour the camera is.
How soon does a speeding notice arrive?
GOV.UK says that within 14 days of the offence you will be sent a Notice of Intended Prosecution and a Section 172 notice. The Section 172 notice must be returned within 28 days, saying who was driving.
What is the difference between a speed camera and an average speed camera?
A fixed speed camera measures speed at one point. An average speed camera system times a vehicle between two or more points using number plate recognition and works out the average over that stretch.
Are speed camera apps legal in the UK?
An Ask the Police answer by the Police National Legal Database, on the West Yorkshire Police website, says devices that only give camera site locations are lawful in the UK and jammers are not. Abroad they may be unlawful. You still must not hold and use a phone while driving.
