Several working groups are seeking to develop new guidelines for assessing motorsports noise amid calls for more research to identify what aspects of the sounds cause annoyance. Lisa Russell reports
For spectators, the noise of a motorsport event can add to the excitement. But for some of those living near a venue it can be annoying or even alarming. How to balance the competing views is difficult enough for an individual track or event, but it is harder still to develop standards that can be applied nationally and internationally to give fairness and certainty to all concerned.
The Institute of Acoustics (IoA) brought together people experienced in the field for a one-day meeting in March, held appropriately at Silverstone. Delegates discussed the various types of noise testing and highlighted the need for more guidance on best practice for four- and two-wheeled events.
Several working groups are bringing together interested parties with the aim of producing guidance on a national or international basis, and the Local Authorities Coordinators of Regulatory Services (Lacors) has just launched a document on motorcycle noise that explains some of the approaches available.

Many circuits have their own local measures in place or have had conditions set by local authorities. A paper by Andy Watson of Acoustic Consultancy Services set the scene. "One of the most important aspects of operating a motorsport venue is to maximise the use, but this is often at odds with noise disturbance in the community. For many venues in the UK this means restrictions in the number of days that they can operate and also may mean restrictions on the type of events that they are allowed to run."

For four-wheeled events, the governing body in the UK is the Motor Sports Association (MSAUK), which is recognised by the world governing body, the Federation Internationale de l'Automobile (FIA). For two wheels, there is the Auto Cycle Union (ACU), recognised by the Federation Internationale de Motorcyclisme.

Both the MSA and the FIA are looking into noise issues. An FIA group met in Paris this month as part of its Environmentally Sustainable Motorsports Commission and the work is ongoing, says MSAUK technical director John Symes – no conclusions have yet been reached. "The noise working group is intent on reviewing existing regulations and noise management techniques and developing updated techniques and regulations, which can hopefully be applied on an international basis," he says. Vehicles travel from country to country for races. "To have consistency would be of great benefit. That's what we are trying to do and it's not going to be easy."

The FIA has a commitment that the research will be finished by September or October. Work is also being carried out for MSA in another exercise that is feeding in to the FIA initiative, says Symes. Watson's paper at the seminar explained that a discussion has begun within the MSA on future noise controls with a view to producing a new action plan by the end of 2010. A discussion document is in preparation.

"When we have gathered the views from within the sport, the plan will be discussed with local authorities and other interested parties and this will result in new noise regulations and an update of the Guidelines for Noise Control first produced in 1996," he said. He expects that the initial plan will be completed by the end of the year and, following further consultation, new regulations could be introduced for 2012, though the timetable is subject to change as the process has not started.
Noise testing has been in place for many years and the aim now is to ask those involved in the sport "where do you think we should be going and what do you think we need to put in place to make things better?" says Watson.

When noise control first began, everyone thought that it was 'the end of motorsport', he says. "It's been the very opposite – it has protected motorsport. Before we were to make any changes and before the FIA are going to make any changes, we really want to make sure that we've got all parties on side." Part of the reason for the discussion document is to ensure that different ideas and approaches arc considered – for instance, events such as racing or rallying have their own ways of controlling noise.

The IoA and Association of Noise Consultants have also set up a working group on motorsport, says Alan Saunders Associates technical director Ed Clarke. It is aimed particularly at reaching a consensus on how to assess and define motorsport noise in order to produce guidance. The plan is to consider wheeled motorsports, including motor cross and circuit racing – it will probably not cover water-based racing such as powerboats.

The working group aims to find a common language for noise levels, making it more straightforward to quantify and define the issues, he says. This would, help, for instance, in negotiations to plan events. Noise for a particular type of racing might be defined effectively by an LAeq measurement related to a single lap. The temptation is to assess the received noise levels in the community, he points out, but there may be a long propagation path with other sources of ambient noise that affect the readings. Another approach might be to quantify the noise at the source and use software to relate it to results at a distance for different wind conditions.

Noise varies for the different types of motorsports, with some producing high LA.:, readings from backfires, bangs and screeches, while others are more constant. Bike racing can introduce other issues, particularly when the bikes jump in the air, changing the propagation path and nature of the noise. Cases can end in court, such as one involving motorsports at a former airfield, Elvington, described to the meeting by Mike Stigwood of MAS Environmental and Mike Southcombe of the City of York Council. An appeal by the operator about the latest noise abatement notice is due to be heard in June.

The Local Authorities Coordinators of Regulatory Services (Lacors) produced guidance last month for off-road motorcycling. Noise from off-road motorcycles: an overview of approaches and sources of information acknowledges the problems experienced by some local authorities from either authorised events or illegal use of land. It has gather information on the approaches taken including seeking to limit use to 14 days a year under the General Permitted Development Order 1995 (GPDO), application of PPG 17 in planning for open space, sport and recreation and duties under the Environmental Protection Act 1990. It also lists some noise controls that have been adopted previously by local authorities, such as a limit on the number of motorbikes and restrictions on the use of PA systems. The document also outlines available powers for unauthorised activities, including those available to the police to give warnings or seize vehicles.

"How can one fairly and accurately assess the degree of noise intrusion?" is the "thorny question" faced by noise professionals when asked to assist in motorsport issues, said Dr Mike Fillery of Fillery Acoustics in his paper. Motorsport noise has many significant differences from other noise sources; differences that will

Alan Blissett carrying out a static noise test. Exhausts aren't always configured as expected
make it easier to pick it out from an ambient noise climate and differences that may render the normal noise assessment methods inadequate, he said.
The UK's governing bodies impose noise controls but there are still some international classes that are unsilenced. including Fl.

"People who are keen on motor racing will say that if you take the noise away, you take away the enjoyment – that noise is an integral part of the activity." says Fillery. "I can subscribe to that – it is exciting." But he wonders how quiet it can be while still retaining the excitement. The level close to the traffic at the start of a race might be, say, 100dB. "If you drop if to 95dB, will that make a difference? Does it stop your enjoyment?" For somebody some distance away, dropping it by 5dB might be the difference between hearing it and not.

"As far as I know, no-one has tested how annoying motor racing noise actually is," says Fillery. It can cause a lot of annoyance – but no-one really knows exactly what the problem is for instance whether it is the character of the noise or that it is readily identifiable or that it causes alarm. "I've certainly heard people say that when they hear tyre squeal then they think that there is car skidding out of control and that there is going to be a crash."

No-one knows the relative importance of the different factors, he feels, but they could be researched. Both Fillery and Bickerdike Allen Partners acoustic consultant David Trew referred to research that has been carried out into entertainment noise – something similar could be done for motorsports.
Unlike other noisy activities such as pop concerts, air travel and industrial noise there is limited available specific technical guidance to assist circuit operators, decision makers and members of neighbouring communities, pointed out Trew. Among his recommendations was for a single, consolidated, code of practice presenting objective guidance covering all motorsport categories. This would include guidance on suitable noise management plans and reference to guideline noise levels based on robust research. "This should also address the relaxation of noise levels for sporting events of importance to public interest, and protect existing venues which already operate satisfactory noise management plans from any further restrictions," he suggested.

The traditional test for vehicle noise is a static one, taken prior to racing. It can give control over individual vehicle noise levels, though by itself cannot guarantee control of community noise, which is also influenced by other factors. Another approach is to use "drive-by" tests, which measure the vehicle as it passes by a monitor. Readings may also he taken at track boundaries or sensitive locations.
Under MSA and ACU regulations, static noise testing is compulsory before a vehicle is allowed on the track. "The test is simple and repeatable which is important for a technical regulation which can result in a vehicle being banned from the event," said Watson. "Although not perfect, the static test has been successful in bringing down overall vehicle noise levels throughout the years that it has been in use."
Advantages, said Mike Bullen of Cirrus Environmental, include its simplicity with minimum investment in instrumentation. But it only provides a snapshot of stationary vehicle noise and is open to cheating.
The static test does not adequately measure the potential for noise emissions when the vehicle is moving, said Fillery in his paper. "Many have tried to correlate the static test with the noise emission from a moving vehicle without success". He too secs it as open to cheating – for example, the test can be invalidated by modern engine management systems that allow the static vehicles to be run at the required rpm but at a much reduced power output resulting in much lower noise emissions.
Chartered environmental practitioner, MSA environmental scrutineer and former competitor Alan Blissett highlighted a host of difficulties that a scrutineer may encounter with carrying out the static test. One is that the limits arc based on maximum revs -- but there is no technical requirement for vehicles to be equipped with a rev counter.

Drive-by noise testing usually takes place at a point where the vehicles are going fast and at maximum acceleration, said Bullen. It is generally carried out in conjunction with time- and date-stamped videos so that results can be checked against an individual vehicle.
"The only use of track testing in the MSA regulations is in kart racing and it has proved difficult to identify individual vehicles during track practice and events due to interference from other vehicles on the track," said Watson. In some other types of events, vehicles run singly and can be identified. "But there is still the problem of repeatability and the fact that the noise has already occurred before action can be taken." However, development in instrumentation and systems means that it may be possible to resolve some of the problems with trackside testing and use this method on more events, he said.
Many venues now have to comply with noise conditions that limit the levels of noise produced at the site and this usually means period LAN levels in the community, said Watson. "This is a fair and reasonable system, but it is not possible to operate effectively by trying to monitor the noise levels in the community." It is almost impossible to produce results that will accurately measure the contribution from the venue.

Fillery says that LAmax has been used successfully to control noise levels on quiet use days at Donington Park. The LAmax limit for sensitive locations was set as at 5dB above the ambient LAcq. r trackside drive-by LA s., was derived for any individual vehicle. Continuous monitoring ensures that any transgressors can be immediately removed from the track. "This provides both circuit operator and the community with an instant response to overly loud vehicles, unlike the delayed response resulting from a daily LAeq,T limit," said Fillery.

"The LAmax may not be the 'best' criterion for motorsport noise but it does offer a practical and pragmatic measure that closely accords with community nuisance and is also in line with the criterion already used by the MSAUK static noise tests for individual vehicles."

NOISE BULLETIN May 2010