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Acoustic cameras: do we want big brother to measure motorcycle sound?

New on our streets: ‘acoustic cameras’ or sound enforcement cameras, a combination of several microphones and a camera, designed to register and fine vehicles that produce excessive noise.

When the sound equipment measures a sound level that is over the limit and recognizes the source (that’s why it has to have several microphones), the vehicle is photographed or filmed. This started eight years ago in the Canadian town of Calgary with a pilot that wasn’t continued. Seemingly, the results of the acoustic measurements could not be used for enforcement. This didn’t stop others: in the Canadian town of Edmonton several cameras with sound recording equipment were installed in 2018, next to sound recording devices that were attached to LED matrix signs. The Brussel region government is still discussing the possibility of sound enforcement cameras since a resolution was proposed in March 2017. In the Paris suburb Villeneuve-le-Roi, near Paris Orly Airport, the first systems are already installed. They are not active yet, according to French law you still cannot fine an offender this way, but this is going to change soon. The British Department for Transport (DfT) has announced that in the UK acoustic cameras will be installed as a reaction to excessive vehicle sound. Finally, the city of Tilburg in the south of the Netherlands is considering acoustic cameras against excessive noise by cars, motorcycles and quads in the inner city.

To be honest, I’m a bit sceptical about these acoustic camera systems. Excessive traffic noise is a problem: it is not just annoying; it is a health issue. There is much research done about this and there are many studies written. Institutions like the World Health Organization and the European Union have long been warning and writing reports about the hazards of too much noise and indicated traffic as a prominent source. So yes, I am convinced that something must be done about that. Also, we know, and often can hear ourselves, that motorcycles can be an important source of sound and of excessive noise. Especially when fitted with illegal exhaust systems with inadequate sound reduction, that are tampered with or still legal exhaust systems with valves that open when the rotations per minute (RPM) of the engine are outside the bandwidth that is used for the type approval tests. Or when some moron doesn’t seem to know how to switch to a higher gear.

Illustration by Wim Taal

As said, something has to be done about that and enforcement is a good way to start with. Better than closing roads or ban motorcycles from towns during the night. We see that already happening in the Netherlands and Germany. But sound is not like speed, where it is technically quite simple to measure the speed and identify the offender. There is a good reason why the present static sound measurements for enforcement must be done in a described precise way, with fixed distances and angles between the exhaust pipe(s) of the vehicle and the microphone, far away from buildings and other objects that can reflect the sound. Just ask a police officer how difficult it is to have a reliable reading that can be used in court and he will not show you a happy face.

I have witnessed several such tests and I know how narrow the margins are. Compare that with the situation where all kinds of vehicles cross those microphones in several directions, where other sources of sound are (in the case of Villeneuve-le-Roi there is even a big airport nearby), where the sound reflects from objects, where the distance between the microphones and the vehicle can be anything.

Exactly for some of the reasons that I mentioned above, the pilot in Calgary was not prolonged after 2011. However, those objections may well be overcome when the technique is further developed and with the right legislation that takes the possibilities of the technique into account. Although in my view, the last would be reversing the order, which is why it didn’t happen in Calgary. My objections are more of a principal nature. In some of the examples I mentioned in the first part of this article, the measures are solely or mainly aimed at motorcycles and other powered two-wheelers. This makes me suspicious. Is excessive noise the only reason? If so, then why not also focus on cars and trucks, or is this a way to discourage motorcycling or even ban them altogether from – for example – the Brussels region?

Besides, enforcement by electronic means is not very effective and can appear to be a way of just collecting money. Often when you receive a fine in the mail, you hardly remember the circumstances, or you just get mad. When you are familiar with the local situation, you adapt your behaviour on that spot or pick another route. We have seen that happen with fixed speed cameras. The alternative way of pointing out to offenders their offence without penalties doesn’t work either, as was shown in Edmonton where instead of mailing out fines, the cameras were equipped with a display board. Motorists would drive by full throttle to see how much noise they could register…

If the authorities really want to do something about excessive noise disturbance, then the old fashioned (and yes, more expensive) way of enforcement by police officers is the only right thing to do.

Written by Dolf Willigers

Motorcyclists being pulled over for a sound test by Dutch police (photo by Dolf Willigers)