More go with the flow

2 July 2007

Some drivers might consider it a lucky day when they catch all the green lights on their way to work, but a university study hopes to use technology to make that less of a chance occurrence scenario.

A research group from Southampton University, along with industry partners, is beginning a two-year project to improve traffic signal control through vehicles' next-generation global positioning systems, which can provide real-time data on their location.

The control system would not rely on traditional GPS, which is only a receiver and cannot transmit information, but a new-style tracking device that couples the receiver with a wireless transmitter — using the control channel on a mobile phone network. These devices relay the position of a vehicle to a tracking centre.

'How many times have you been at the back of a queue of traffic and it's been going through a green light, but the light doesn't quite stay green long enough for you to get through?' said Ben Waterson, the lead researcher of the project.

'Or how many times do you sit at a junction and the lights are red for you and green for people who have long gone?'



Induction loop

Waterson, a lecturer in the school of civil engineering at Southampton, said his project is a continuation of a strand of research on real-time traffic monitoring that began in the 1970s.

For many years, one of the most popular ways of providing this information was with induction loops, which drivers see as black rectangles in the middle of the road. The loop is made up of a simple, coil wire transceiver that senses when a vehicle goes over it.

The problem with controlling traffic signals with induction loops, Waterson said, is it only gives information about the traffic at that particular point on the road. This is a specific problem, he added, when there are a lot of cars pulling on to the road from side streets between the detector and the traffic signal junction.

'If you could actually monitor where the individual vehicles were, we would know there was one more vehicle in the queue,' said Waterson, 'and an extra couple of seconds of green light would save that person an awful lot of time and not really cost anyone else much time at all.'

Waterson envisages future traffic control systems would work by using detectors to locate the GPS in individual vehicles. It would also incorporate real-time video image processing to track cars that do not contain positioning systems.

The latter technology is already used, said Waterson, in long tunnels through mountains, where information such as the breakdown of a vehicle needs to be immediately known.

The researchers will collaborate with Southampton City Council and Siemens Traffic Control for the next two years in testing their theories on commuter simulation models.

After that, Waterson said his team might find that GPS is not the only technology needed to improve traffic signal control.

'One question is: What level of accuracy of the data do we need to be able to do this?' he said. 'It may well be that GPS isn't actually enough on its own, and we need to go one stage further by using technologies such as advanced real-time video image processing.'



Privacy concerns

If GPS is deemed to be the right technology to improve traffic signal control, Waterson said car manufacturers will have to incorporate the technology in more vehicles to get the advanced control systems to work.

In addition, transport officials will have to quell any privacy concerns that drivers might have about their cars' GPS being tracked.

'A lot of time when we're talking about monitoring where people are, it means monitoring them over a long period of time,' he said. 'The advantage of this system is as soon as you're through the junction it can forget where you were. It doesn't need to know who is in the car or any details about it except for the fact that it's coming along, wants to go through the junction, and once it goes through it can forget it again.'

Waterson said an advanced traffic signal control system can also lead to a more environmentally and economically sustainable road transport system.

'When you're sitting at a red light and you've got a green light for a road that has no traffic, effectively you are costing time, and time, is money,' he said.

He added that a smoother running transportation system means vehicles brake and accelerate less and produce fewer emissions.