Doubts On Overseas Road Design Data

Press, Volume CVII, Issue 31462, 31 August 1967, Page 8

Doubts On Overseas Road Design Data

(N.Z. Press Association) ROTORUA, August 29. From the evidence it appeared that it would be dangerous to place too great a reliance on overaeaa roading design data, unless it could be shown that the data was obtained under conditions similar to thoae in New Zealand, said Mr G. J. Donne, S.M., today. He was summing up during a special sitting dealing with allegations that excessive axle loadings on logging trucks was causing damage to roads in the Bay of Plenty. The Magistrate said that the hearing was at his request so that he could hear general evidence on the matter as a means of assisting him in fixing penalties. He said, that each case would be treated on its merits, and that the Court would never adopt any form of yardstick as a result of the evidence placed before it. In his summary, the Magistrate said that he concluded that he had not erred in the matter of penalties imposed, and that he had, in considering cases before him, directed himself properly. Study Suggested

Dealing with a suggestion from Mr D. S. Beattie, Q.C., Auckland, who appeared for the operators, that a commission should be appointed to study the problems of roading in New Zealand, the Magistrate said it was not for the court to make such a recommendation but he felt the suggestion was a sensible one. Mr Q. P. M. Almao, appeared for the Transport Department, and Mr Beattie, with him Mr E. C. East, was briefed by the Bay of Plenty. Carriers’ Central Executive.

Jack Ewen Henry, general manager of the Forestry Division, New Zealand Forest Products, Ltd., Klnleith, said his company, either under its

own ownership, or through its contractors, had 90 logging trucks going to Mount Maunganui daily. Under Review

The firm was concerned at the number of prosecutions taken against the firm’s vehicled or those of the contractors, and the matter was one which was under constant review, supervision and disciplinary action. “We have held conferences with the Transport Department The owner-drivers and our own drivers in an effort to control what is alleged to be the deterioration in the roads over which the vehicles travel. “I am satisfied that the roads in many parts were not built to cope with the normal permitted weights for the logging business. “We feel that within reason we can control total weight, but when it comes to individual axle weights we face a real problem.’’ The Incidence of overloading did not have to be very high to cause substantial shortening of road pavement life, said the Ministry of Works resident engineer, Rotorua, Mr J. McTaggart. Mr L. Evans, a Rotorua consulting engineer, said the road surface between Tokoroa and Rotorua, and Rotorua and Mount Maunganui, was damaged only in certain places. Factors causing this could include such things as inadequate design, inadequate or irregular compaction of the soil under the road metal, inadequate or variable quality of road metal, inadequate or variable maintenance or the variable quality and or quality of bitumen. Expert, Differed He said world experts equipped with the best available research facilities, differed on the causes and progress of road failure and on factors that influence design.

The Magistrate said he concluded that while some damage resulted from overloaded axles, the extent of it must be in doubt until research in New Zealand with New Zealand materials and under New Zealand conditions was complete. He said there was no evidence to show that road damage was any greater in the Bay of Plenty than that which occurred elsewhere in New Zealand.