Electric scooter dude

Electric scooter warning noise research sounds note of optimism

Image credit: Dott

The University of Salford’s Acoustics Research Centre has received additional funding to continue its work to develop a universal sound for e-scooters, operating in partnership with Dott, an Amsterdam-based micromobility operator, and the Royal National Institute of Blind People (RNIB).

The new funding backs progress towards a universal sound for e-scooters, as part of the ‘Safe and Sound’ project.

Dott (aka emTransit B.V.) is a European mobility operator with over 30,000 electric scooters in Belgium, France, Germany, Italy, Poland and now the UK. The company aims to expand its UK operations and recently won a tender for the Transport for London e-scooter trials. Dott scooters is looking to mitigate potential safety hazards to pedestrians with the use of an Acoustics Vehicle Alerting System (AVAS) for distinct e-scooter category.

The three-way partnership between Dott, the RNIB and the University of Salford was launched in 2021 with the report 'Generation and Analysis of Artificial Warning Sounds for Electric Scooters'. It has supported research into the first feasibility analysis for using artificial motor sounds on light electric vehicles. The project aims to understand whether artificial motor sounds on electric scooters can improve audible detectability of these vehicles by people with visual impairments while avoiding contributing additional noise pollution to our cities.

In response to a brief by RNIB, funded by Dott and HEIF, Salford Acoustics has created a series of sounds that underwent extensive testing in their renowned acoustic research facilities. The preliminary research results have indicated that improved noticeability of e-scooters using sound can be achieved without adding to noise pollution in cities.

The initial research findings were the development of a system to generate a warning sound in real time – using a Raspberry Pi computer, within a Python coding environment – according to the scooter’s operating conditions (e.g. speed).

A microphone array fitted below the handlebars of the scooter provided a strong output with a maximum output level exceeding 50dBA in the direction of travel above 1,000Hz (at 1.5m from the rider position), with the array radiating predominantly in the forward direction, as requested by RNIB.

A laboratory study was also carried out to gauge pedestrian awareness of an approaching e-scooter with and without a warning sound added. With the warning sound, the detection time of the approaching scooter decreased by 0.48 seconds. With the scooter moving at 15mph, this translated to noticing it at a distance 3.2m further away than when there is no warning sound.

Dr Antonio J Torija Martinez, principal investigator of the project at The University of Salford, said: “We are delighted with the progress made on this project. Based on initial research, we found that the addition of a well-designed acoustic signal can significantly increase vehicle awareness and ultimately safety.

“The additional funding secured from the Innovation Strategy Fund allows us to carry out further research into the optimisation of acoustic awareness of light electrical vehicles that will be effective for those with visual impairment in complex urban environments. Our research will also be exploring how we integrate human responses to the design of acoustic solutions for e-mobility.”

The ‘Safe and Sound’ project has now kicked off in consultation with several National Blind Associations across Europe. Phase one of the research will focus on three main areas:

  1. Impact of different sounds on users and the public.
  2. The feasibility and deployment of the sounds developed to work in tandem with vehicle hardware capability.
  3. Undertaking trials in different European locations.

Maxim Romain, COO and co-founder of Dott, said: “As we work to provide safe, reliable and sustainable travel across our cities, the progress with Salford Acoustics offers encouraging steps towards a sound which could help identify vehicles, in a way that respects the environment of our streets. We are committed to supporting further research and collaborating with the wider industry and the partners in this project to find a global standard which can make shared e-scooters safer for both riders and pedestrians.”

Robin Spinks, strategic lead on innovation projects at RNIB, added: “Light electric vehicles pose a significant safety hazard to many people with sight loss. We're delighted to be collaborating with the Safe and Sound project at Salford as we continue to pioneer solutions to the detectability of quiet vehicles."

The project is aiming for the roll-out of a future global standard on light electric vehicle technical standards and is continually seeking out collaborations with other partners to complement and enhance its research.

The August 2021 report concluded that "a good compromise between noticeability and annoyance can be achieved with a well-designed warning sound", while ending with the cautionary observation that "further research is needed to design warning sounds with an optimal balance between noticeability and annoyance".

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