Car parks can be a hassle - you have to roll down your car window and reach out to get a ticket from the dispenser on the way in, and then have to reach over and pay the cashier on the way out. The engineers at Germany's Fraunhofer Institute for Material Flow and Logistics, however, have come up with something easier. They've developed an RFID (radio-frequency identification) tag system that allows drivers to pass unimpeded in and out of car parks, with parking fees being automatically deducted from an online account.

The system, which is called VIATAG, was designed for Munich's motionID technologies.

Vehicles using the technology have an adhesive foil RFID chip transponder, mounted on the inside of their windshield. The device measures just 1.5 by 10 centimeters (0.5 by 4 inches). Readers located above the entrances and exits of the car park emit an electromagnetic field, which provides power to the transponder. It transmits its vehicle's unique 12-digit code to the reader, in the ultra-high frequency (UHF) range - the distance between transponder and reader can be up to eight meters (26.25 feet).

By noting the times at which each vehicle enters and leaves the car park, a central database is able to keep track of how much parking time they have used. At the end of each month, the total amount owing is automatically paid online by direct withdrawal.

No personal data is stored on the chip, and its 12-digit code is encrypted. Should a thief wish to steal it anyway, the device becomes unusable when removed from the windshield.

After being field tested for several weeks, VIATAG is now in use in car parks in the cities of Essen, Duisburg and Munich. The Fraunhofer researchers believe the system could also be useful in locations such as highway toll booths, gas stations, car washes, and car rental agencies. Australia's Queensland Motorways, in fact, is presently introducing the system for paying toll fees.