The conflict of soundscape requirements with the introduction of alert signals

Abstract

Quiet road vehicles have to be equipped with acoustic alert signals for type approval to account for their potentially reduced audibility. According to the FMVSS No. 141, the alert sound has to be recognizable as a motor vehicle in operation that allows blind and other pedestrians to detect nearby electric vehicles or hybrid vehicles operating at lower speeds. Unfortunately, the detailed minimum sound requirements for type approval vary from regulation to regulation, for example, between FMVSS No. 141 and UNECE No. 138. The manufacturers can consider brand-related alert signal design within certain ranges but must adapt their alert sounds to the respective regulations, because an international harmonization of the signal requirements is missing. In this context, the impact on traffic noise in general and on soundscape in particular seems to be rarely systematically discussed. It is expected that some side issues will emerge with the systematic introduction of alert signals. Moreover, the effectiveness of the different regulations regarding the significant reduction of pedestrian collision risk was not systematically analyzed so far. This paper will discuss potential shortcomings of the introduction of alert signals regulated by law, and the implications on urban soundscapes will be outlined. Quiet road vehicles have to be equipped with acoustic alert signals for type approval to account for their potentially reduced audibility. According to the FMVSS No. 141, the alert sound has to be recognizable as a motor vehicle in operation that allows blind and other pedestrians to detect nearby electric vehicles or hybrid vehicles operating at lower speeds. Unfortunately, the detailed minimum sound requirements for type approval vary from regulation to regulation, for example, between FMVSS No. 141 and UNECE No. 138. The manufacturers can consider brand-related alert signal design within certain ranges but must adapt their alert sounds to the respective regulations, because an international harmonization of the signal requirements is missing. In this context, the impact on traffic noise in general and on soundscape in particular seems to be rarely systematically discussed. It is expected that some side issues will emerge with the systematic introduction of alert signals. Moreover, the effectiveness of ...