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or even replacing, the recent pedestrian alert sound safety standards. Technical solutions, such as a vibration transponder for persons at risk, are not considered adequate because a highly trained sense (hearing) would be replaced by a less trained sense (touch). Moreover, silent cars will be a potential danger to all traffic participants including those not using a vibration
Acknowledgments
My thanks to Klaus Genuit, among others, for working togetheronthesubjectofpedestrianalertsignalsandfor supporting my work over the last 15 years. Moreover, I thank Wade Bray and Arthur Popper for their valuable comments and suggestions on the manuscript.
transponder; other vulnerable road users without References
transponders including children, cyclists, elderly persons; and distracted pedestrians (EBU, 2019). In addition, pedestrian-centered approaches based on smart devices shift responsibility from the driver to the pedestrian, requiring that the pedestrian has to pay (extra) attention and that the respective device is functioning properly.
Car manufacturers are working to achieve a vision of accident-free driving by implementing more and more assistance systems such as automatic emergency braking or automatic pedestrian detection. Thus, the use of alert signals might ultimately become obsolete due to technological progress that would result in accident- free driving; this of course depends on the phase out of existing vehicles due to service life or to legislation. Car- to-car communication can be used to avoid unreasonable emission of alert sounds; for example, when 10 cars at an intersection already emit an alert signal, it might not be necessary for additional cars to do so.
Future technological systems can also be used to help visually impaired persons safely navigate through unsafe conditions such as crossing roads. Indeed, in areas with loud background noise, it would be unsafe to rely only on the audibility of the alert system of a car. Yamauchi et al. (2015) observed that quiet vehicle warning sounds in environments with loud background noise are not audible and thus of limited benefit in addressing the danger that such vehicles pose to pedestrians. Here, ideas to adapt alert sounds to the respective sonic environments are currently being discussed to optimize the balance of noise pollution and sufficient audibility (Kournoutos and Cheer, 2019).
The ultimate goals must be to avoid fatal accidents, to support visually impaired persons (and other groups needing additional support), and to minimize any impact on environmental noise leading to noise annoyance. The search for the perfect solution must guide further discussion of alert signals beyond nonscientific debates.
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European Union (EU). (2014). Regulation (EU) No 540/2014 of the European Parliament and of the Council of 16 April 2014 on the sound level of motor vehicles and of replacement silencing systems, and amending Directive 2007/46/EC and repealing Directive 70/157/ EEC. Official Journal of the European Union 158, 131-195.
European Union (EU). (2017). Commission delegated regulation (EU) 2017/1576 of 26 June 2017 amending Regulation (EU) No 540/2014 of the European Parliament and of the Council as regards the acoustic vehicle alerting system requirements for vehicle EU-type approval. Official Journal of the European Union 293, 3-7.
Fagerlönn, J., Sirkka, A., Lindberg, S., and Johnsson, R. (2018). Acoustic vehicle Alerting systems: Will they affect the acceptance of electric vehicles? Proceedings of Audio Mostly 2018 on Sound in Immersion and Emotion, Association for Computing Machinery
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Federal Motor Vehicle Safety Standard (FMVSS). (2019). Minimum Sound Requirements for Hybrid and Electric Vehicles. Docket No. NHTSA- 2019-0085, Federal Motor Vehicle Safety Standard No. 141, Notice of proposed rulemaking, National Highway Traffic Safety Administration (NHTSA), US Department of Transportation, Washington, DC.
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