Quiet-car risk disputed
Worries about electric vehicles have been tested, writes Mark Hinchliffe
NOT only are hybrid cars dangerously quiet for pedestrians, but so are some modern, conventional cars.
An RACQ study has found no discernible difference in audible detection of approaching vehicles between petrol-electric hybrid cars and conventional cars from the same manufacturer.
The study by RACQ researchers Russell Manning and John Ewing follows complaints in the US by organisations representing pedestrians and blind people that hybrids are dangerous because they are so quiet.
Manning says the study, conducted with the help of Vision Australia, tested four vehicles with 11 volunteers, five of whom were blind.
‘‘There was no significant difference in the detection distances be- tween hybrid and similar-sized conventional vehicles in a typical urban environment with typical urban ambient noise levels,’’ his report reads.
‘‘This is not to say that hybrids are not a risk, only that they are no more of a risk than equivalent, conventional vehicles under these conditions.’’
Manning says noise regulations are not a concern.
‘‘To suggest that modern cars, be they hybrid or conventional, are too quiet could lead to the conclusion that noise regulations are too stringent,’’ he says.
‘‘We believe lower noise levels are, on balance, good from an environmental and social aspect.’’
Volunteers in about 40 per cent of cases were unable to detect ve- hicles approaching at 60km/h from a safe distance.
‘‘Had they been in the path of the vehicle, contact would have resulted and in several cases potentially serious injury or fatality may have occurred,’’ the report found.
Manning says tyre and wind noise are the main audible signals of approaching vehicles, either hybrid or conventional.
‘‘The lack of, or reduction in, mechanical noise from hybrid vehicles did not appear to significantly increase the risk factor,’’ the report said.
Several manufacturers of hybrid and electric vehicles have been working to create artificial noise.
Nissan engineers worked with blind people to create special frequencies for their Leaf electric vehicle, expected to arrive in Australia in the next year.
Toyota and its luxury branch, Lexus, which account for the bulk of hybrid cars available in Aus- tralia, are also tackling the worries about noise.
Lotus Engineering has developed a realistic engine sound for electric motors that varies with speed.
The world’s first all-electric supercar, the Tesla Roadster, is getting a ‘‘space sound generator’’ on its Brabus-tuned models.
Owners will be able to set their Tesla to make noises similar to a V8 engine, a racecar engine or two ‘‘futuristic soundscapes’’ named ‘‘Beam’’ and ‘‘Warp’’.
It is likely more sound effects will be added to electric cars until governments step in and legislate for the new technology.
The Pedestrian Council of Australia has called for changes to the Australian Design Rules to set a minimum noise for vehicles powered by an electric motor.
Vision Australia wants hybrid vehicles fitted with beepers to operate when the vehicles are running on electric power only.