30 m.p.h. Limit ‘Could Be Raised’

Press, Volume CVI, Issue 31225, 24 November 1966, Page 1

30 m.p.h. Limit ‘Could Be Raised’

The 30 m.p.h. speed limit could be raised in some areas of Christchurch, the Superintendent of the City Council traffic department (Mr J. F. Thomas) said yesterday after his return from a 15-week study tour overseas.

“In view of what I have seen overseas, I think that in Christchurch there are areas at present subjected to a 30 m.p.h. speed limit, and with no high-density housing or building, where possibly an increase in the existing speed limit could be applied,” he said.

“I think, on the other hand, that in some other areas the 30 m.p.h. limit is too fast.”

In one United States city, Davenport, lowa, a survey two years ago had shown that where there was no highdensity housing nor large volume of traffic, the general 25 m.p.h. speed limit was not observed. In some cases 60 to 80 per cent of motorists exceeded the limit. It had been recommended that speed limits be fixed according to prevailing conditions, and now limits ranged from 25 to 40 miles an hour, and were strictly enforced. The traffic authorities were confident that the accident rate had decreased and that 85 to 90 per cent of motorists complied with the limits, said Mr Thomas.

The “green wave” system of traffic light co-ordination, multiple stop signs at intersections, parking meter penalties and alcohol tests for drivers were among other aspects of traffic control and enforcement which particularly interested Mr Thomas during his tour.

“Under the ‘green wave’ system, you have your traffic lights co-ordinated so that a motorist, if he maintains a given speed, can go completely through an area controlled by the system,” he said.

A series of programmes was

fed into a master controller to co-ordinate the lights at peak periods, computers being used in some instances. During the rest of the day the lights worked normally. Mr Thomas saw the system working in Cologne, where a traffic expert told him that if it were adopted in Christchurch the movement of traffic would be freed for years ahead. The expert said he would be happy to come here to examine any plans for the system. In Davenport eight intersections were controlled by compulsory stop signs on all four approaches. “If the number of accidents at an intersection is relatively high, and the traffic flow is insufficient to warrant the installation of lights or having on officer on point duty, this can be used as an intermediary medium.” Where the signs had been erected in Denver the severity of accidents had been reduced to a minimum

Of various devices used overseas for testing drivers who had been drinking, Mr Thomas singled out the “breathaliser,” which determined the percentage of alcohol by the change in a chemical solution when the driver breathed into a tube.

“The breathaliser is an extremely fair type of instrument, I think,” he said. In Denver, Colorado, a movie camera was used to record a motorist’s performance when he underwent this and other physical tests, and the film assisted both the driver and the enforcement authorities. Mr Thomas, who was accompanied by the traffic engineer (Mr H. E. Surtees) studied traffic control in Europe, Britain, the United States and the Far East. He met heads of traffic departments, traffic engineers and members of Automobile clubs, visited universities where traffic research was done, and also studied major cities from helicopter. The two men attended the annual conference of the Institute of Traffic Engineers at Cincinnati, and the road safety congress and international study week in Barcelona.

“I think that Christchurch, relatively speaking, is fully abreast of the times, and that with present and continued planning for future traffic needs we can cope with conditions which will eventually arise toward the latter part of the century,” Mr Thomas said.