Brigade Electronics, the Kent firm which pioneered reversing alarms in the UK in 1976, has launched its Quiet Vehicle Sounder (QVS) at the CV Show.
Brigade has called the QVS “probably the biggest breakthrough in road safety since the reversing alarm” and chairman Chris Hanson-Abbott has campaigned for over a decade to require the fitment of a QVS to electric vehicles, which he has dubbed “silent killers”.
After 11 years and over 50 meetings the UN finally ratified regulation UNECE R138 specifying the standards for acoustic vehicle alerting systems (AVAS) and from September 2019 all new models of road-going battery electric, hybrid and fuel cell powered vehicles, including electric cargo bikes, must come fitted with an approved AVAS.
All new EVs registered after September 2021 will also have to fit an approved device but Brigade is urging operators already putting quiet vehicles on the roads to fit the sounders – which cost under £300 from Brigade – now to help prevent collisions with vulnerable road users.
Because EVs are nearly silent, pedestrians are often unaware that they are approaching or about to pull away. A study the Guide Dogs for the Blind shows that pedestrians are 40% more likely to be struck by an EC than a diesel or petrol vehicles.
Under UNECE R138, the AVAS must start emitting the sound, which is limited to 75dBA at a distance of 1m, as soon as the ignition is switched on, though it is disabled when the park brake is applied. The volume of the AVAS automatically increases as the vehicle speeds up but cuts off when the vehicle reaches 30kph by when tyre and other noise will be an adequate alert to the vehicles’ approach.
The pitch of the sound also changes as the EV speeds up and slows down, mimicking an internal combustion engine. After much deliberation, the UN committee ruled out fitting a ‘pause’ button enabling the driver to manually disable the AVAS.
One reason agreement on the standard took so long was the difficulty in finding a sound that was clear enough to be audible in heavy city traffic but would not disturb residents at night. Like Brigade’s smart ‘white sound’ reversing alarms, the QVS uses broadband sound frequencies to ensure it is directional and easy for pedestrians to locate the source.
Hanson-Abbott said: “We trialled over 40 different sounds and ended up with our patented QVS. It doesn’t need a lot of decibels because the broadband spectrum means it is impossible to mask the whole sound.”
The complexity of UNECE R138 means that while most of the volume EV manufacturers will produce their own AVAS, it will undoubtedly put off some smaller OEMs who will probably look to Brigade to supply its QVS product.
TfL, which operates a number of electric buses in London, is working with the Transport Research Laboratory to develop its own slightly different AVAS to differentiate its buses from electric cars, vans and, at some point, trucks.
l What does it sound like? To hear a demo – it’s a no more than a low hum – go to https://brigade-electronics.com/products/reversing-and-warning-alarms/quiet-vehicle-sounder. The QVS consists of five sounds of different frequencies and pressures as specified by the regulations.