Road Network Operations
& Intelligent Transport Systems
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Law Enforcement

Enforcement agencies in many countries use ITS to assist with their work on road safety and traffic legislation enforcement. Examples are speed enforcement cameras, red light enforcement cameras (such as the one illustrated below), Weigh in Motion (WIM) and vehicle self-monitoring applications such as in-motion tyre condition monitoring.

 Red light enforcement camera (copyright CA Traffic)

There are specific systems to detect offences such as red light running or speeding. In many cases these systems automate the process from detection of the offence to issue of a fixed penalty notice to the vehicle keeper or driver. There are also surveillance systems that are used to spot drivers going the wrong way on the carriageway, stopping in no-stopping zones such as tunnels, or parking illegally.

Other systems are aimed at preventing offences and violations, such as “alcolock” breathalyser immobilisers and Intelligent Speed Adaptation (ISA) (See Driver Support) which are capable of preventing the commission of offences in the first place (drink driving or speeding). They double as driver support systems as well as enforcement systems.

Schemes where drivers have to pay to use the road or to park would be pointless without an enforcement regime, as very few drivers would pay unless there was a realistic risk of incurring penalties. Tolling (See Electronic Payment) and parking often use ITS to enforce correct payment (See Case Study: Free-flow Tolling, Chile).

The prevalence of ANPR for these processes is interesting. The London Congestion Charge in 2003 was criticised by the ITS profession for being ANPR-based when newer technology such as satellite or tag based charging could have been considered. At that time, many also expected Electronic Vehicle Identification (EVI) to be just around the corner – ready to replace number plates as the first means of identifying a vehicle. Ten years later, ANPR remains very widely used to identify vehicles, and EVI seems to have lost momentum through lack of acceptability, mainly based on privacy concerns. (See Privacy)

Legality of Operations

Automated enforcement is only possible if the device and the evidence it provides is reliable enough to withstand the test of authenticity in court. Having a regulatory framework and systems and procedures for end-to-end verification of enforcement operation is the key to success.

The transition for a situation where a person detects an offence and initiates a prosecution or issues a fine – to a situation where an automated system carries out these tasks – cannot usually be managed within a regulatory or legislative framework that predates automation. Since any change to the framework will usually need to allow for the automatic identification of vehicles and their location – due regard must be paid to issues of privacy of the driver. (See Privacy) An appeals process is good practice.

An example of a successful appeal is an incident where a vehicle was filmed making an illegal turn triggering the issue of a fine. Out of camera shot, behind the vehicle, was an ambulance on call. The car driver was making the illegal turn as the safest way of letting the ambulance pass by. The fine was cancelled on appeal.

Traffic Management Infringements

These can be enforced using either semi or fully automated systems. (See Enforcement) Typically, a camera is used to record the offence and, via Automatic Number Plate Recognition (ANPR) to identify the vehicle. How the offender is then contacted and penalties are issued, will depend on the legal framework in a specific country. Usually, legislation will have been enacted to govern contact and enforcement processes in the way that authorities wish to handle traffic management infringements. If the law allows full automation without any human verification, the system can issue and post the notice of a fine or a summons to court. If not, there may be a requirement for a person to check the image, verify the offence and/or the identity of the vehicle, in order to authorise the next step of the process.

Other Driving Offences

Offences such as driving the wrong way on the carriageway or a ramp, or stopping where this is not allowed (such as in tunnels or on bridges) can easily be detected using CCTV. Previously, detection would mainly have been carried out by control centre responsible for monitoring computer screens and taking manual action when spotting dangerous driving. It is now becoming more common to use video analysis of images to create alarms to alert staff. The system itself does not undertake the enforcement. If appropriate, enforcement officers will be despatched to detain the offending driver.

Where specific taxes, insurance policies, or certificates of road worthiness are associated with individual vehicles, Automatic Number Plate Recognition (ANPR) offers a simple way of linking the vehicle with its centrally held record and checking if all records are in order. If not, the vehicle can be stopped and appropriate action taken.

A new development is more sophisticated use of surveillance technology, both camera- and radar-based, which detects infringements – such as following too close to the vehicle in front, or illegal lane changes.

In-car Offences

Remote, camera-based surveillance can also be used to detect offences such as not using seatbelts, using a mobile device in an illegal manner, and even smoking in situations where this is illegal in a vehicle. (See Policing/Enforcement) Again, the image captured by the camera will be used to provide evidence for a fine or a summons.

Parking Offences

ITS for parking management, including parking enforcement, are now common. In the case of enforcement, cameras and ANPR can be used to detect parking where it is not permitted, or to detect overstaying time limits in legal parking places.

Electronic Payment

The enforcement of charges relating to parking and tolling is an important and widespread ITS application. (See Electronic Payment) All tolling systems, whether large scale motorway tolling or individual bridges or tunnels, rely on adequate enforcement to function. Reliability of equipment and procedures is key. If the system states that a vehicle parked in a certain location, or was present in a tolled area, at a certain time, the operation of the equipment (such as its reliability and time/place accuracy) should beyond dispute. (See Case Study: Stockholm Congestion Tax)

Tolling schemes that rely on RFID tags can be enforced by detecting and stopping vehicles without tags. Schemes where the vehicle number plate is associated with non-payment of the toll are enforced by camera. The vehicle keeper will be fined if the vehicle is shown to have incurred a charge that has not been paid. As with parking enforcement, a vehicle with numerous outstanding payments is likely to be eventually listed as “of interest” and a special effort made to find and stop it the next time it is picked up by cameras.

To enforce payment, it is essential that all the ITS equipment used complies with type approval and other legal requirements in the country of operation. (See Case Study: Type Approval (UK) )


ITS enforcement applications for freight are common. (See Enforcement) One that is so ubiquitous that it is often overlooked is digital tachographs used for certain classes of heavy goods vehicles. This collects and presents information needed by law enforcement officers who are investigating whether driving hours and rest break legislation is being followed, It is done in an easily downloadable and tamper-proof way – and offers the possibility of remote interrogation.

Weigh in Motion (WIM) is another important freight application that enables the detection of overloaded vehicles without having to stop the vehicle for a manual check. The overweight vehicle is brought to the attention of enforcement officers on the road ahead, who have powers to stop the vehicle. Automated processing of fines for overweight vehicles is rare. An overloaded heavy goods vehicle is often associated with other offences – such as drivers’ hours, illegal condition of vehicles, or regulatory offences by the owner. A physical vehicle stop is often useful in bringing these related offences to attention.

Driver support systems

These are systems (See Driver Support) that prevent – rather than detect – offences. Examples are driver drowsiness detection, which can help to stop the driver from committing a variety of dangerous driving offences:

  • alcolocks, which do not allow the engine to start unless the driver provides an acceptable breath sample
  • Intelligent Speed Adaptation (ISA) that informs the driver of the prevailing speed limit throughout the journey. ISA can be advisory or mandatory. If it is mandatory, the system will not allow the speed limit to be broken

Systems that monitor the driver’s fitness to drive are increasingly being installed in new vehicles. Alcolocks and ISA are common in public fleets in the Netherlands and Sweden. These systems have much to offer in supporting road safety, but they do also raise issues of liability. (See Liability and Privacy)

Advice to Practitioners

Using ITS for road traffic law enforcement is a very important ITS application which, while not always popular with the public , have already saved many lives by preventing road accidents.

It is worthwhile keeping up with new developments (See ITS Futures) in using ITS for enforcement purposes. It is not so very long ago that Weigh in Motion (WIM) was a new application – whilst first uses of technology to check tyre condition on moving vehicles are now taking place in Germany.

Practitioners should be mindful of how unpopular some applications are with drivers – such as automated parking enforcement and speed enforcement cameras – in particular single fixed point speed cameras rather than point to point enforcement cameras where the vehicle speed is measured and calculated over a length of road (such as a kilometre).

The unpopularity of measures can lead to challenges to enforcement proceedings . Challenges are often made on the basis that the equipment used to detect the offence was faulty or not legally compliant in some way – and that there was no offence. To deter spurious legal challenges it is important to keep the equipment type approval, calibration and maintenance regimes up to date, transparent, and well publicised. (See Case Study: Type Approval of ITS Devices)

One way of overcoming resistance to enforcement measures is “marketing” activity to publicise the positive outcomes. This can help prevent public opposition and political lobbying. In Ontario in Canada, this eventually led to speed enforcement cameras being removed from the roads.


Reference sources

Association of Chief Police Officers (ACPO). 2011. Guide for the Operational Use of Speed and Red-Light Offence Detection Technology. London, ACPO.

Berg, C., and Gjerstad, B. 2009. Road Safety, Technology and Privacy. Stockholm, Proceedings of the 2009 ITS World Congress.

Blythe, P. and Pickford, A. 2006. Road User Charging and Electronic Toll Collection. London, Artech House.

Directorate-General for Mobility and Transport. 2011. Intelligent Transport Systems in Action. Brussels, European Commission.

Gaventa, J. 2005. Policing Road Risk: Enforcement, Technologies and Road Safety. London, Parliamentary Advisory Council for Transport Safety.

Harrod-Booth, J., Kaltwasser, J. and Lupges, C. 2012. Dangerous Goods Transport – Telematics, Standards and Regulation. Vienna, Proceedings of the 2012 ITS World Congress.

ITS (UK) et al. 2008. Civil Traffic Enforcement Certification of Approved Devices. Edition 1, London, Department for Transport.

Mansourkhaki, A. 2011. Evaluating the impact of a speed enforcement pilot project. Lyon, Proceedings of the 2011 European ITS Congress.

Mitas, A., Bugdol, M., Rygula, A. and Konior, W. 2012. Weigh-in-Motion systems for pre-selection, enforcement and data collection in Poland. Vienna, Proceedings of the 2012 ITS World Congress.

Parliamentary Office of Science and Technology. 2009. Postnote no 322: Intelligent Transport Systems. London, POST.

Pickford, A. et al. 2007. Technology Options for Road User Charging in the UK. London, ITS (UK).

Skelton, N. et al. 2002. Intelligent Transport Systems – A Crime Reduction Tool – Practical applications. London, Home Office.

Skelton, N. 2009. Traffic Law Enforcement Technology in the UK. London, ITS (UK).