Beware of silent EVs!

If you think electric vehicles or EVs will translate into fewer accidents, it’s time to rethink.

Maybe, the EVs entry would reduce the carbon emission to a limited extent. Here again, the hoopla over the switch from the most popular Internal Combustion Engine or ICE-based vehicles to EVs will make Planet Earth more liveable has to be taken with moderation.

One thing, however, is clear EVs will not eliminate road accidents. There is no concrete proof supporting the life-saving characteristic of EVs. On the contrary, surveys and expert analysis prove that such a notion is false.

If you think EVs produce lesser noise pollution as against ICE, remove such mental cobwebs. “When moving at higher speeds, EVs produce roughly the same wind and road noise as ICE vehicles, “ says John Seabrook. (1) Well, the interesting point to note is what he adds: “… at lower speeds they operate in near-silence: electricity flows from the battery to the motor, which spins with a barely audible hum. Therein lie the promise and the peril of EVs for city dwellers.” Wow!

According to him, unlike vision, smell, and taste, all of which dim when consciousness shuts down for the night, hearing is a 24/7 operation. The annoying automobile engine noise while on the move — slow or otherwise — provides a cushion against collisions.

In 2016, there were 30 different EV models, with total sales topping around 160,000 vehicles. With the campaign promoting green energy and saving fuel costs for a cleaner environment, the EV craze has caught on like wildfire. “Global EV sales reached 6,75 million units in 2021, 108% more than in 2020. This volume includes passenger vehicles, light trucks, and light commercial vehicles. The global share of EVs (BEV & PHEV) in global light vehicle sales was 8,3 % compared to 4,2 % in 2020. BEVs stood for 71 % of total EV sales, PHEVs for 29 %. The Global auto market improved by only 4,7 % over the crisis year of 2020,” writes Roland Irle. (2)

Global auto majors, cornered by governments across the world on the strength of Tesla’s success in the EV sphere, reluctantly reducing investment in ICE and attending to a new future with EVs as primary motorized passenger and cargo movers. Naturally, the EV population will explode, thus leading the safety of electric vehicles to the forefront.

Is noise a life-saver, particularly when it emanates from a moving motor vehicle? It appears so. The criticality of noise has to be viewed from the noise pollution angle.

With the move from ICE to EV, expert opinion has it that “recent advances in green alternative fuel technologies bring about the reduced fuel consumption, reduced CO emission and reduced vehicle noise emission.

A recent report turns the spotlight on the noise emission angle, which it says has “important implications for the safety of vulnerable road users, such as cyclists and pedestrians, particularly those who are visually impaired, since the usual noise produced by an ICE is now absent.

“In low-speed environments particularly, aerodynamic and road-tyre sounds are negligible meaning road users have few available auditory cues to an approaching vehicle. Collision with pedestrians even at speeds of 30kmph can be serious, so the lack of noise emission may present a substantial risk.”

How do we overcome this safety risk? Experts recommend adding synthetic sounds as a warning in the absence of real engine sounds. Here again, there is a catch. Such synthetic sounds must be “optimal for health and social well-being of the neighborhood.”

Low-speed EVs are the greatest risk to vulnerable road users because the noise emitted from the friction between the tires and the road surface and the aerodynamic noise are minimal. Thus at low speeds, an EV may be near silent. These risks will be most prevalent in urban areas which enforce low-speed limits.

For a moment, forget the low-speed EVs. When an EV is involved in an accident, the chances of electrical systems’ integrity getting compromised cannot be ignored, and such things increase the risk of electrical shock. “If electrical isolation is damaged such that the positive and negative terminals in the circuit come into contact with the vehicle bodywork, then subsequent human contact with the bodywork will result in electric shock. Nonetheless, EV makers have taken note of such life-snatching risks and trying to eliminate this risk.

The Dresden University of Technology, Germany, researched how visually impaired, blind and sighted participants responded to the sound produced by ICE, EV, and HEVs. Pedestrians detected the sound of EVs later than ICE vehicles: ICE at 36 meters and EV at 14 meters. The synthetic sound did not offer any different results.

Researchers, however, give a rider. “While it is possible that noise contributed, the cause of the accidents was not investigated in this study, so it cannot be concluded that the higher crash rate attributed to HEVs was due to the lack of engine noise.” The jury is still out, maybe.

Nissan took the challenge of low noise emission seriously. It developed Vehicle Sound for Pedestrians VSP system for the 2011 Nissan Leaf EV to help address the potential quiet car concern. This system emits a digitally generated signal from an onboard speaker to provide auditory cues to pedestrians during low speed for forwarding movement and reverse. (5)

The characteristics of the sound profile utilize knowledge of human ear sensitivity, age-related hearing loss, typical background noise conditions, and visually-impaired pedestrian feedback and preferences gathered by surveys in Japan and the USA.

Ref:
(1) Annals of Sound: On Alert — Should quiet cars be heard? (Pp. 24–30), New Yorker, August 8, 2022
(2) https://www.ev-volumes.com/
(3) https://ankinlaw.com/do-electric-vehicles-pose-additional-hazards-in-a-crash/
(4) Evaluation of Accident Statistics on Electric Vehicles Regarding the cause of the accident — Work Package 2.2 (Albero Project),
(5) https://www.researchgate.net/publication/275224729_Development_of_Approaching_Vehicle_Sound_for_Pedestrians_VSP_for_Quiet_Electric_Vehicles#:~:text=A%20system%20called%20Approaching%20Vehicle,speed%20forward%20movement%20and%20reverse.

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