Adaptive acoustic vehicle alerting sound, AVAS, for Electric vehicles Results from field testing

Acoustic vehicle alerting sound (AVAS) is implemented on electric and hybrid vehicles (inelectric mode) as a safety tool to warn pedestrians at low vehicle speedsO. The main objective of this project has been to evaluate if the present regulations for AVAS could be improved, by including an adaptive functionality, with relation to the level of background noise. A test of different sound levels of AVAS and with different levels of background noise has been conducted using a panel of 8 test persons. Of these, 3 were blind/visually impaired. In the test, the test persons were asked to press a button whenever they could hear the approaching vehicle (at 20 km/h). By so, a detection distance could be established depending on the sound level of AVAS and background noise level. The results showed that when the background noise is relatively high (around 65 dB), the level of the AVAS signal should be somewhat increased, if shall function as a safety warning signal. For the specific electric vehicle used for the test, the present sound level of AVAS, has no warning effect at 20 km/h, even with a low background noise level (40-50 dB), as tyre/road noise is dominating at this speed. However, the detection distance under these conditions is higher than a proposed safety margin of 11 m. Oppdragsgiver: BUFdir