Not unlike the unnecessary shutter noise of a camera phone, aimed at preventing intrusive photograph-taking by mimicking the manual release of a shutter, electric cars will also be forced to make a noise in order for other road users to be aware of their presence.
The regulation forcing these vehicles to emit noise will come into force in Europe, and the USA, in 2019 and will apply to all types of electric motors: hybrid, plug-in hybrid, 100% electric, extended-range electric and those that form hydrogen fuel cells.
The main proponents of the electric car emphasise that its silent driving is a great advantage in terms of noise pollution, and brings a different experience to driving. Many manufacturers claim that the absence of combustion noises reduces some levels of stress at the wheel. It is this silence however that poses a risk, specifically for pedestrians.
Noise and road safety have traditionally gone hand in hand. According to US Department of Transportation data, there is an additional 19% chance that an electric vehicle will hit a pedestrian compared to a conventional one. With this new regulation, which in that country will be enforced as of September 1, 2019, it is estimated that some 2,400 victims related to these situations can be avoided. These statistical victims are all associated with the noise that electric cars do not emit because in all other respects, it is demonstrated that electric cars are as safe, or more so, than traditional ones.
In America, it will be mandatory for all electric motor cars weighing less than 4.5 tons to emit noise above when travelling in excess of 30 kilometres per hour, both forward and in reverse. Neither can the system be disconnected, as some vehicles currently allow.
In Europe, the legislation will advance slightly sooner, as of July 1, 2019, and although the exact requirements are still to be confirmed, the European Commission already drafted a series of recommendations in 2011 which said that 20 kilometres per hour was the optimum noise-producing speed. Another difference for Europeans is that the date, 2019, refers to the new models only, those vehicles already on the road will have until 2021 to adapt.
Of course there are still two questions still remaining. Firstly, what type of noise will the vehicles have to omit? Sci-Fi films might show vehicle floating with a gentle hum, or a futuristic beep, and for the staunch defenders of the electric car, they believe that the sound they emit must be unique, away from the noise that we are accustomed to vehicles with thermal motors.
Luckily, it is highly unlikely that the verbal commands similar to, “Caution! Vehicle Reversing” will be adapted, as the EU proposal, for its part, states that “the sound generated by electric cars must be continuous and provide sufficient information to pedestrians and other vulnerable road users. The sound must be easily identifiable from the behaviour of a vehicle and should sound similar to the sound of a vehicle of the same category as an internal combustion engine.”
This contrasts with the vision of the head of the French company Arkamys, Philippe Tour. The company is dedicated to the development of acoustic warning systems for vehicles (AVAS). Tour believes that electric trains do not have to sound like something we already know, and think that manufacturers would prefer to opt for other types of sounds.
For its part, the Guide Dogs charity in the United Kingdom has written a series of recommendations aimed at manufacturers to help them define noise with the safety of the blind:
- The vehicle must be heard regardless of its location and speed.
- That the noise generation system must take into account when a vehicle has to operate in quieter conditions.
- That same system must inform the proximity of the car, especially if it is in a situation of temporarily stopping.
- The sound generated should mimic the sound generated by an internal combustion vehicle of similar characteristics, performing similar manoeuvres.
- That the system cannot be disconnected in any case.
Our final burning question on the subject also deals with a more futuristic, although increasingly modern phenomenon, the self-driving vehicle. Once the roads are flooded with vehicles driving themselves, will the noise then be necessary?
Everything seems to indicate that electric cars will end up sounding similar to those with a combustion engine, given the safety requirements that legislators have contemplated. However, this situation does not have to be permanent, at least if we look at the long term. To do this, we must introduce in the noise equation the complex variable of the autonomous vehicle.
Already, we have seen how these vehicles can operate on roads in mixed traffic with little problem. The majority of incidents involving these vehicles still being down to driver error, the human failing to do its part, and whereas the majority of incidents produce more anecdotes than cause for reconsideration, the ability of these vehicles to detect pedestrians and stop in the event of obvious risk has already been proven to be effective. This may lead us to think that in the future these benefits can restore silence to electric cars.
However, as we have been looking from the past to the future, we must remember that we are still very much in the present, and, although these developments are happening around us, at this stage there are no specific plans for the day when infallible autonomous driving becomes the norm.