The Invisible Referee

21st Century Traffic Control: The Invisible Referee University of Southampton

Scalextric With Traffic Conrol

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Get Behind the Wheel

Try your hand driving on our specially customized Scalextric track, it has been fitted with traffic control! There are two traffic light controlled junctions on the track with different control mechanisms. Can you work out the difference?

The Science

Modern traffic light controlled junctions don't just work on a timer system. They use a large number of sophisticated sensors to detect where the vehicles are and optimise their decisions. Some of the sensor technologies employed are:

  • Inductive Loop Sensors: These sensors are buried in the tarmac of the road surface and exploit the phenomenon of electro-magnetic induction" to count vehicles as they drive over the sensor.
  • Microwave Sensors: These little sensors are mounted on poles by the road and detect vehicles by bouncing microwaves off them. They can also estimate the speed of approach of a vehicle using the Doppler effect.
  • ANPR Cameras: ANPR stands for "Automatic Number Plate Recognition" These cameras use computer vision technology to read individual vehicle number plates. This allows them to not only count vehicles that pass but keep track of vehciles as they move through the system.
  • The Future

    In the future vehicle's on-board computers will carry WiFi communications technology allowing them to communicate with other vehicles and with infrastructure. Vehicles will be able to use their own on-board sensors (e.g. GPS) to measure their position and speed and broadcast this over WiFi. This will give the invisible referee even more data with which to judge the state of the road and make smart control decisions.

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