Investigation of the external noise emitted from electric buses in New Zealand and the need for acoustic vehicle alerting systems to improve road user safety

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infrastructure - vehicle, mode - bus, mode - pedestrian, place - australasia, planning - safety/accidents, technology - alternative fuels


AVAS, disability, electric bus, noise, pedestrian safety


The purpose of this research was to investigate the differences in noise levels and detectability between electric buses and diesel buses, and to explore the suitability of acoustic vehicle alerting systems (AVASs) for electric buses in New Zealand. The methods included a literature review of bus noise and AVAS issues in New Zealand and overseas; controlled testing to measure the noise levels of diesel and electric buses; and participant testing to measure the frequency and detection distance of different buses on urban streets in Wellington and Auckland. The literature review found that while there are known safety and detectability problems with electric vehicles of all kinds, AVASs are relatively new, and their effects are unclear. Our controlled testing revealed that electric buses are quieter than diesel buses at very low speeds (10 km/h) but there was no difference at 30 km/h, and electric buses were slightly louder than diesel buses at 50 km/h. Our participant testing had mixed results. There were no significant differences in bus detection in Wellington, either by bus type (electric or diesel) or participant impairment status (low-vision or non-impaired). In Auckland, however, participants were more likely to detect a diesel bus than an electric bus, and they detected diesel buses earlier, on average. Electric buses were less likely than diesel buses to be detected at all, and when they were detected, they were closer to the participant than the diesel buses were. We concluded that further testing is required before deciding whether to introduce AVASs into electric buses in New Zealand. We recommend laboratory testing of potential systems and further street trials to find the most appropriate solution to bus detectability and pedestrian safety, while maintaining the amenity value of the low noise of electric buses.


Permission to publish the abstract has been given by Waka Kotahi NZ Transport Agency, copyright remains with them.