Big Savings Claimed For Area Traffic Control

Press, Volume CVII, Issue 31462, 31 August 1967, Page 12

Big Savings Claimed For Area Traffic Control

"The Press" Special Service

WELLINGTON, August 30.

Community savings expected from an area-wide traffic control signal system at Christchurch were estimated at $500,000 to $750,000 a year, said the Christchurch City Council’s traffic engineer (Mr H. E. Surtees) at the New Zealand roading symposium in Wellington.

Mr Surtees said area control represented the best value-for-money investment in transport, and it should qualify for a big National Roads Board subsidy. He advocated its urgent application to New Zealand cities.

The increasing application of area-wide traffic signal con trol was probably the most significant development in traffic engineering in the last 10 years. Area control was the application of traffic signals to a street network rather than to an isolated intersection. In general, though not essentially, the signals at individual signals worked under a central control device which instructed the signals according to a sequence designed to provide a smooth flow of traffic.

The aim was to provide a high standard of service to traffic, based on minimising overall delay and stopped time and optimising travel speeds. Additional advantages were often obtained from increased traffic capacity and fewer accidents.

The control tended to be selective in its benefits, frequently providing convenience to the majority of motorists, or those moving in principal streets, at the expense of those making minor movements on cross streets. Some early systems fell short of desirable standards, a factor contributing to the tremendous upsurge of research and application of area control techniques. Other factors included an appreciation that urban motorways did not in themselves provide the answer to inner city congestion and the importance to any urban community of an efficient, safe transport system. Mr Surtees said Britain led the world in the use of vehicle-actuated signals. A system had recently been introduced in West London linking 70 intersections and 30 signal-controlled pedestrian crossings, and at Glasgow an area of 1 square mile, with 75 intersections, would soon be under computer supervision. Toronto Studies

Pilot studies on a Toronto experiment in area control led to the claim that if the flow of traffic was improved by even 10 per cent the direct benefits to the municipality would exceed 10 times the cost of installing a full-scale system and the indirect benefits to the motorist and the community could be many times this again. It had been calculated -in the West London experiment that a reduction in delay of only two to three per cent would be sufficient, in terms

of savings to the community, to provide an adequate return on the capital and other charges. New Zealand had traditionally used vehicle-actuated signals. Because of the uncertainty surrounding the problem of network co-ordin-ation using this equipment and in the knowledge that valuable information would come from current experiments, it could be argued that the best plan for New Zealand’s major cities was to wait and see. “This would be a serious mistake,” said Mr Surtees “Our central areas are already in the grip of costly traffic congestion. ‘Around the corner’ results and new techniques will always be there to lull the conservative engineer into delay. The only proper course is to capitalise on existing equipment and overseas experience and to get stuck in and make the best job with the tools available, always providing flexible designs to allow the use of new developments.” Preliminary estimates of the Christchurch proposal for area control based on the ultimate provision of a com-puter-controlled vehicle- actuated programme formation system covering 80 intersections were $600,000. If area supervision was not provided, all but 25 of the 80 would within the next 10 to 15 years need simple vehicle-actuated signals costing $270,000. The annual savings of $500,000 to $750,000 expected would be a handsome return on an outlay of $600,000.