Mobile phone data will be monitored to ease traffic congestion as part of a major trial. York City Council will use drivers' and passengers' phone signals to track how cars move around the city in an effort to ease traffic jams in the historic city.

The new system will collect signals via the internet or using sensors on the roadside, and if successful could be rolled out across the country.

The council said the detectors would be fitted to lights, bollards, and other street furniture and would detect and process anonymous "signatures" from people using mobile phone services.

The data used will be harvested by beacons which collect data called a "MAC address" from passing phones, a unique code each device broadcasts as it searches for WiFi networks or Bluetooth devices. The only way to opt out of the scheme would be to turn off WiFi and Bluetooth. The code for each car would change every day.

In the future the council may also buy anonymised data from mobile phone companies.

Data will also be collected from satellite navigation systems and eventually will also track "connected cars" which have their own WiFi systems and provide drivers with information about traffic and provide parking assistance.