Trafficking in safety

Motorway pile-ups caused by poor visibility could be eliminated by a beacon that warns motorists of stationary traffic ahead, its US inventors claim.

The device, roughly the same shape and size as a cat’s eye, would be placed at regular intervals beside a traffic lane.

Using radar, the beacon would monitor the speed of passing traffic, relaying the data to a local communication node for processing.

If the node sensed rapidly slowing or stationary cars, it would then instruct the beacons to flash a particular colour according to the conditions ahead, alerting drivers to oncoming hazards.

Its designers at the University of Florida, Gainesville, said the beacon could also be used to designate evacuation routes in areas prone to hurricanes, or during other disasters, moving traffic away to clear access for emergency vehicles.

They believe the system could also be used to control vehicle flow at traffic lights, adjusting red and green signals automatically to clear build-up from a particular direction.

The system relies on ultra-wideband (UWB) radar, which broadcasts extremely rapid pulses at passing traffic then measures the time the signal takes to bounce back to determine the location and speed of passing traffic.

‘The radar sends out billions of pulses each second,’ said Florida University’s associate professor of civil engineering Dave Bloomquist. ‘This means the volume and speed of the traffic is not a problem.’

The units would be placed along the roadside at intervals of just over 30m, and would monitor traffic continuously. Each beacon would be powered by a solar cell and back-up battery, and would be able to display green, red and yellow lights.

Roads fitted with the device would be divided into one to two mile sectors, each with a communication node able to transmit data from the beacons to each other and a central control.

The whole unit – including the UWB radar and electronics to provide wireless communication with other beacons – would be around the size of a pack of cards.The system would need no human intervention, though police and rescue officials could programme or disable the system remotely if necessary.

Collected data could also be used to measure traffic volume, helping road planners to determine future transport policies.

‘Transport officials have been very interested in the proposition,’ said Bloomquist. ‘We are now hoping to have a prototype system up and running within the next year to 18 months.’ He estimates that mass production would mean each beacon could cost as little as £18.

Sidebar: Military video system offers traffic control without roadworks

A military video imaging system could hold the key to enabling automatic monitoring and control of traffic in the UK without having to dig up the road.

Current monitoring systems, such as those used to control traffic lights, rely on fibre loops embedded in a road’s surface.

These detect changes in electrical current caused by metal vehicles overhead and use this to tell when traffic is waiting and the lights need to be changed to green.However, installation and maintenance of the loops requires roadworks, causing congestion.

The video-based Machine Vision system developed by Qinetiq consists of a camera and image processing system that sit in a box connected to a traffic light or placed beside the road, viewing, determining and recording the type of vehicles passing from above.

The system will be coupled with hardware designed by traffic flow specialist AGD Systems, and will be able to interpret video data to count vehicles, determine their type by measuring their length, and monitor their speed. It will be used in a range of applications such as controlling motorway traffic speed.

‘Current video-based systems can face problems in bad weather and poor light,’ said Mike Cooper, technical manager for Machine Vision at Qinetiq. ‘As machine vision is built to defence standards, this will allow it to be accurate in all weathers.’

He believes the system could be used to automatically control traffic lights in towns, as well as allowing active, automatic control of speeds on motorways.

If the system detected that motorway congestion was occurring owing to the bunching of vehicles, the system could then change local display boards, telling drivers to reduce their speed and keep the traffic moving.

Meanwhile, its ability to classify vehicle types means the system would prove useful to he Highways Agency in the collection of road use data.