What is the biggest threat to health and safety: Quiet or noisy vehicles?

Abstract

It is assumed by US federal authorities that vehicles, driven in electric mode, either hybrid or pure electric vehicles, are so quiet that they are a safety hazard for pedestrians and cyclists in traffic. A regulation on this topic is already proposed in the United States, and in Europe, the Parliament has voted in favor of a similar regulation. ISO has worked out a measuring method for the “quietness” of vehicles; assuming that this can be used to require quiet vehicles to have some sound added. Based on earlier publications on this subject by the author, and reviewing some recent papers and reports, the author explores the assumed problem, and puts it in the perspective of traffic safety as well as the detrimental effects of noise on humans. Special concern is given to the relation between “quiet” and “noisy” vehicles. It is argued that it is far more justified to work in toward reducing the noise emission of the noisiest vehicles in traffic than adding noise to the quiet ones, as in any traffic situation, masking by other sounds is more important than the sound level per se, and masking is largely influenced by noisy trucks, busses, and motorcycles.