Technology: Traffic lights learn to go with the flow

日期:2019-02-26 07:06:13 作者:单五 阅读:

By MICK HAMER ‘SMART’ traffic lights will soon be cutting queues at road junctions. Researchers at the government’s Transport and Road Research Laboratory have developed a system known as MOVA – short for microprocessor-optimised vehicle actuation – that can alter the timing of lights at isolated junctions to minimise the time vehicles have to wait. MOVA is a slimmed-down version of the long-established SCOOT technology, which already controls networks of traffic signals in London and other major cities in Britain and abroad. SCOOT (which stands for split-cycle optimisation) is a larger system which enables a computer to control dozens of interconnected traffic lights. MOVA has been made possible by the increasing miniaturisation of electronics. It is also a relatively cheap technique: 10 years ago, SCOOT was economic only if the computer controlled a large number of signals. Now a small microprocessor can control a single junction. Detectors buried under the approach roads to a junction count vehicles. The microprocessor balances the delays to the queue waiting at a red light against the volume of traffic favoured with a green light. When the time lost by those waiting exceeds the time gained by those moving, the lights change. The microprocessor is continually balancing these competing demands and calculating the optimal cycle of changes. On average, MOVA cuts delays by 13 per cent. However, the system cannot help with very heavy traffic. If the traffic is bad enough to cause substantial queues on the approach roads, MOVA switches automatically to a programme which gives the maximum time of green lights to oncoming traffic. At isolated junctions such heavy traffic rarely occurs. MOVA is likely to be particularly useful at junctions with uneven traffic flows, such as those near sports stadiums or cinemas. The system was first tested for three years at a junction on London’s North Circular road, near Wembley Stadium, where rock concerts, football matches and the freeing of Nelson Mandela conspire to cause erratic traffic flows. These trials have now been expanded to cover 20 junctions throughout Britain,