To help protect pedestrians - especially the blind and partially sighted - Lotus Engineering has created a device to simulate engine noise for electric and hybrid vehicles.

Traffic noise may be a nuisance, but for blind and partially sighted pedestrians it is a life saver. It is vital to hear approaching cars yet hybrid vehicles are too quiet, especially at low speeds. Toyota, Lexus and Honda are increasing the number of hybrid models they offer while Chevrolet - with the Volt - and other manufacturers are climbing on the petrol-electric bandwagon meaning the problem is set to get more widespread.

One solution is to artificially generate engine noise as an audible warning of an approaching vehicle. Lotus Engineering has years of experience developing its 'Sound Synthesis' as part of a suite of noise management technologies. The Lotus system works by taking readings of vehicle speed and throttle position to measure engine load. Sounds are based on those of a typical petrol engine and are relayed through a waterproof speaker mounted near the radiator. The speaker projects the sound ahead of the car so practically no sound is heard once the vehicle has passed. Should the petrol engine start - to charge the batteries or for extra performance - the sound synthesising software automatically stops generating engine noise.

A spokesman for the Royal Society for the Prevention of Accidents (RoSPA) welcomed the system: "The sound of an approaching vehicle is a warning that most pedestrians will use before making the decision to cross the road. New electric engines make vehicles much quieter, so we need to look at ways of ensuring the safety of pedestrians. We welcome innovative solutions which address this."

Lotus claims that the system could be fitted to existing electric and hybrid cars "without breaking the bank". In the words of Mike Kimberley, Group Lotus chief executive, "Our technology increases pedestrian safety, while retaining the [hybrid] car's environmental benefits."

John Lambert - 22 Aug 2008