Thursday, March 08, 2007

Tail lights grow in the dark

Brake lights warn that a car in front is slowing down but they give no indication of how sharply it is braking. Respond too slowly and you could slam straight into it. To try to prevent this, particularly at night and in poor weather, Zhonghai Li and Paul Milgram at the University of Toronto in Canada propose fitting cars with brake lights that grow larger the harder the driver brakes.

They began by experimenting with novel brake-light configurations in driving simulators, to see what changes would indicate most clearly how heavily a vehicle is braking. The arrangement they eventually decided on was a triangle, with an upper brake light placed slightly above two lights on either side. When the driver just touches the brakes, the lights form a small triangle close to the centre of the car. As braking gets heavier, all three lights get bigger, and those to the left and right also move outwards in proportion to the braking force. With the brakes fully applied, the lights get larger still and move right out to the edge of the car.

Rear-end collisions accounted for 30 per cent of all US road crashes in 2003, including 5 per cent of fatal collisions, according to government figures. Shape-shifting brake lights could be built into cars using low-power LED arrays, say the researchers, who hope to interest car makers in the idea.


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