An infrared camera should help with the toll calculation by showing how many people are in a car. Picture: Tsui Sing Yan Eric,
Reading aloud A new measuring system should certainly capture the number of occupants in passing cars. A camera measures the absorption of invisible infrared radiation through the faces of passengers. With the meter, municipalities could make a city or road toll on the number of inmates, explains British developer John Tyrer of Loughborough University in Leicestershire. Also, so-called Mehrfahrerspuren could monitor, which may be used only by cars with a certain number of inmates, as they are common in California, for example. From the roadside or from a bridge, a light source emits infrared (IR) light into the passenger compartment of the car. The researchers take advantage of the fact that IR light with a wavelength of 1.5 thousandths of a millimeter, the windshield passes unattenuated, but is completely absorbed by the human skin. Other items in the car such as seat cushions, dashboard and also the clothing of the occupants reflect the light. In the image of the infrared camera, faces appear as black areas.

The researchers compare these black areas with other features of the reflected light and can thus close with a reliability of 95 percent on the number of people in the car. Since the system captures the facial skin, it is not to be fooled by dolls or large-sized photos. The researchers have already successfully tested the camera arrangement on their campus and on a bridge in Scotland. Whether that with about 100, 000 euros per installation quite expensive device is financed by municipalities, however, doubt industry experts. However, developer John Tyrer believes that local authorities now have much better and safer ways to stagger road tolls by the number of passengers.

New Scientist, online service ddp / Martin Schäfer


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