Noise cameras on our roads

noise cameras

It looks like our vehicle speed cameras are about to get a friend. From around the end of the pandemic, news stories started flooding in from all over the world (i.e. France, USA, Canada) and including the UK, talking about the installation of noise cameras on the roads that assist in identifying “noisy” vehicles.

One has to wonder why the sudden global interest. Did we perhaps collectively become more sensitive to noise after the quietness of the pandemic? Should classic car drivers and motorcyclists be worried? Is this just another attack on fossil fuels (since electric vehicles are notoriously quieter)? Or is this an additional cash cow for the government?

The latest polling from used car buying service ChooseMyCar[1] shows that seven in ten Brits (71%) support noise cameras in cities, whilst more than two-thirds (67%) support this in rural areas.

In response, at the end of April 2022, Transport Secretary Grant Shapps declared that he wants to “banish the boy racer” from our roads with a new initiative to tackle excessive vehicle engine and exhaust noise in the worst affected areas.

A search for Britain’s noisiest streets has been launched by the Department for Transport (DfT) with 4 areas across England and Wales set to trial new phase 2 technology to help stop rowdy motorists from revving their engines unnecessarily or using illegal exhausts.

Since the technology is in the design phase, MPs are being invited to submit applications to trial new innovative noise cameras in their local area, helping to ensure communities can enjoy their public and residential spaces peacefully.

Intermittent Road Traffic Noise Pollution

When establishing the sound level emitted by a vehicle for Type Approval purposes, there are precise rules in place, with fixed distances and angles between the exhaust pipe(s) of the vehicle and the microphone, away from buildings and other objects that can reflect the sound.

Since 2019, the DfT has been trialling cameras in various parts of the UK. The cameras work by measuring the amount of noise coming from a vehicle and, should a car be too loud, it will trigger the camera to take a photo and automated number plate recognition (ANPR) will clock the registration plate and ensure that a penalty is sent to the offending driver.

Legal Framework

The Road Vehicles (Construction and Use) Regulations 1986[2] contains the UK legislation that can be used in the enforcement of excessively noisy vehicles, however, it does not provide any fixed noise limits. Regulation 54 of these Regulations, requires exhausts and silencers to be maintained in good working order and not altered so as to exceed the noise emissions by the type of approved exhaust fitted by the manufacturer. Regulation 97 provides that “no motor vehicle shall be used on a road in such a matter as to cause any excessive noise which could have been avoided by the exercise of reasonable care on the part of the driver.” It is an offence under section 42 of the Road Traffic Act 1988 to use on a road, a motor vehicle which does not comply with these requirements.

Since noise emissions from different vehicles differ (and in some cases substantially) the noise camera may contain a variety of triggers and more research is required to provide a good correlation between the noise reading from the camera and the Type Approval level for that vehicle. There are also vehicles that have no corresponding Type Approval drive-by sound emissions limit, and in such cases, these vehicles could either be exempt or be assessed against a different noise level, perhaps a noise limit appropriate for the vehicle subcategory. In any case, at this stage, it may be sensible to set trigger levels with a large margin in order to avoid incorrect fines.

It should be noted that “excessive” noise emissions from the exhaust of vehicles form part of an MOT test and this is generally based on the subjective judgement of the MOT tester. This subjective test can also be undertaken by a police officer on the road.

UK Government Research

The Government’s Phase 2 study on the issue of acoustic/noise cameras was published in August 2021. The findings of this study will inform the next phase which will include the assessment of:

  • potential vehicle noise thresholds for enforcement
  • the suitability of acoustic cameras for enforcement

The August 2021 report concluded that:

  • it is possible for a noise camera to identify vehicles and for measured noise levels and speeds to be assigned to individual vehicles under certain conditions, theoretically and in practice;
  • further development is required to overcome various technological and acoustic challenges before one can be considered proficient for enforcement such as;
  • automating post-processing of individual noise camera components so that the data outputs are linked together, taking into account the small-time differences between each component encountering a vehicle as it passes the noise camera;
  • identifying vehicles and matching noise levels to them for more complex traffic scenarios, such as vehicles passing the noise camera in quick succession or at similar times on opposite carriageways
  • using purpose-built components to improve the identification of vehicles.
  • development of a portable solution.
  • future noise cameras should consider the use of a microphone array (i.e. like the “Medusa” system trialled in Paris) and the collection of acceleration data.
  • further research is required to characterise driving styles or behaviours that are considered ‘excessively noisy’.
  • from an enforcement perspective, it is considered that adverse driving styles should not be enforced separately with a noise camera but any evidence that can be used to demonstrate that a driving style may have resulted in a vehicle being logged as ‘excessively noisy’ would be helpful in the evidence package
  • the analysis of the data from the prototype noise camera has indicated that it is possible to numerically define what an excessively noisy vehicle might be, based on the measured maximum noise levels from vehicle pass-bys, and that the use of a ‘not-to exceed’ noise limit is viable
  • the relationship between objective and subjective definitions of excessively noisy vehicles requires an examination to ensure that enforced pass-by noise limits achieve their aim
  • further data is needed for motorcycles to robustly conclude whether it is appropriate to apply different noise limits to cars and motorcycles;
  • as the potential application of noise cameras for addressing the issue of excessively noisy vehicles is leading to the development of technologies that could one day be deployed for enforcement, the use of a design and installation specification or standard will become increasingly important;
  • direct application of existing vehicle pass-by measurement methodologies (ISO 362 and ISO 11819) to use for a noise camera is not possible due to logistics with the placement of the measurement equipment and the difficulty of controlling variables in a roadside environment; however, some aspects can be adopted for such a standard; the standard will ensure that certain criteria are met to maximise the performance of the noise camera and that there is uniformity in their performance (so that two noise cameras behave the same); it would also enable prospective suppliers to optimise their products to the selected enforcement criteria; the development of a design and installation specification will be a requirement to preserve the integrity of the evidence package and to withstand legal challenges.

The Experience from Kensington and Chelsea

In late 2020, the London Borough of Kensington and Chelsea launched its own noise-camera pilot scheme following 35 official complaints relating to engines revving between June and August 2020.  The use of such noise cameras is made possible using an innovative Public Space Protection Order (PSSO) put in place by Kensington and Chelsea to reduce excessive noise from vehicles.

The pilot noise cameras[3], were made live on Tuesday 22 September 2020.  The systems store video and sound levels when an excessively noisy vehicle is detected. When the threshold level is exceeded, the cameras record the sound level and provide detailed footage of the offending vehicle. The Council has fined offenders (a fine of £100) and in extreme cases, on conviction, it can apply to the Magistrates Court to seize the vehicle.  Since then, Kensington and Chelsea have made the system permanent and expanded the area of the PSPO. It should be noted that as a PSPO is being used for enforcement, RBKC is not using a specific threshold noise level for enforcement. The noise cameras do use triggers but the decision to enforce is on a case-by-case basis following a review of the whole data package collected.

Councillor Johnny Thalassites confirmed[4] that classic cars were not the target of the new machines. He said drivers would need to ‘consciously’ look to break the noise rules to be penalised and added that ‘sensible’ motorists were unlikely to be fined. He said: “I don’t think the aim is to target any individual kind of vehicle as such. I quite like seeing supercars and things on our streets if they are driving responsibly”.

If you are a local authority that requires specialist assistance in relation to the implementation of noise cameras in your jurisdiction or you are a motorist that has received a relevant fine and is in need of acoustic expert input, please do not hesitate to contact Finch Consulting.




[3] It should be noted that there are other noise cameras available which are being trialled in other parts of the world that could be suitable for UK roads


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