With the anticipated consumer adoption of electric transportation, a concern of public safety has emerged: electric vehicles travel quietly and generate relatively little noise, potentially presenting a safety hazard for pedestrians. We are all accustomed to the engine sound that conventional gasoline-operated vehicles produce. Although most people welcome a reduction in noise pollution, a quiet vehicle can present a safety risk for both pedestrians and bikers, in particular when walking through parking lots or when crossing streets.
For years, the Federal Highway Administration of the US Department of Transportation has been providing guidelines to incorporate a noise reduction design goal for highway traffic noise abatement. While regulating motor noise of internal combustion engine (ICE) cars and trucks is a matter of quality of life, at the same time engine sounds have been intuitively used by everyone (including other drivers) as a safety alarm of an approaching vehicle.
The National Highway Traffic Safety Administration (NHTSA) reported that in the last few years there has been an increased rate of hybrid vehicle accidents involving pedestrians in comparison to gasoline-powered ICE vehicles. Based on the US Pedestrian Safety Enhancement Act of 2010, signed into law in January 2011, the US Department of Transportation (USDOT) has been performing studies to establish a vehicle safety standard that would set requirements for the warning sound. Results are expected to be finalized before mid 2012. The studies involve testing of electric vehicles and all types of hybrids when traveling at relatively low speeds of twenty miles and under. The proposed policy intends to protect pedestrians, bikers, and the visually impaired from potential accidents involving hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and all-electric vehicles (EVs). The alert sounds will allow pedestrians and bikers to better detect the presence of such quieter vehicles.
While many consider the inaudible operation of EVs as a benefit, others are concerned with the silent vehicles. At low speeds, there is little air resistance against the vehicle. Some noise is produced at higher speeds however it is not as loud as ICE’s noise levels that we are so familiar with.
Called Vechicle Sound for Pedestrians (VSP), several electric vehicle manufacturers have begun addressing this pedestrian safety matter by adding warning sounds.
With its launch of the 2012 Ford Focus Electric, the company has been in the process of engaging the public in selection of the car’s alert sound. Ford presented four different warning noises and has asked the public to rank these on the company’s Facebook page. To vote, click here.
Other companies are offering noisemaker kits to add to hybrid vehicles. According to a Toyota press release last year, a noisemaker for Prius hybrids became available in Japan last August. The device is installed under the hood and designed to alert pedestrians audibly to the presence of a quiet vehicle. It emits a humming sound similar to an electric motor, which rises and subsides in pitch relative to the vehicle’s speed, consequently helping indicate the car’s proximity and travel. The device is available in Japan through authorized Toyota dealers and Toyota parts & accessories distributors. Although its use is voluntary in Japan, the sound device meets the Japanese government guidelines for hybrid and electric vehicles warning system. Toyota also plans to launch several versions of the device for use in gasoline-electric hybrids, plug-in hybrids, electric vehicles, as well as the planned fuel-cell hybrid vehicles.
Earlier this summer, Nissan announced that its Leaf electric vehicle would have an audible pedestrian warning system. Similarly to Toyota, the sound system includes a speaker under the hood and a synthesizer in the dash. Although the device will be activated automatically at vehicle start-up, the driver will be able to turn it off. The sound and pitch were designed to be audible to all age groups. In addition, in reverse motion, the Leaf’s noisemaker will produce an intermittent sound, similar to the warning systems on trucks.
For the Chevy Volt, the pedestrian-friendly alert system is a standard feature. The General Motors system is called ‘Pedestrian-Friendly Alert System’ and is manually activated by the driver. In the same way as the Leaf, the driver can de-activate the horn chirp by using the turn signal lever button.
Hopefully, noisemakers for the new generation of hybrids and electric cars will not go along a similar path of mobile phones’ ring-tones.
Check the US Department of Transportation – Federal Highway Administration Report on Highway traffic Noise – Analysis and Abatement Guidance, January 2011(PDF)