ROAD CORRUGATIONS.

Auckland Star, Volume LXIV, Issue 116, 19 May 1933, Page 8

ROAD CORRUGATIONS.

HIGHWAYS board research. Conclusions resulting from research into the problems of corrugations on road surfaces were given in a lecture by Mr. A. Tyndall, engineer to the Main Highways Board, before the technological section of the Wellington Philosophical Society. Facts adduced from the research, he said, were as follow: — The spacing of corrugations had been found to range from 20 to 37 inches. Spacing was related to the speed of vehicles, e.g., a certain car travelling at 25 miles an hour produced corrugations 21.14 in apart, while the same car travelling on the same road at 40 miles an hour produced them at intervals of 29.32 in. High pressure tyres were much more conducive to their formation than balloon tyres. Certain types of shock absorbers had a deterrent effect on their formation. Dry weather encouraged their development. "The increased use of balloon tyres in recent years should have theoretically rearded formation of corrugations," Mr. Tyndall said, "but the effect has apparently been much more than balanced by increased speeds of both cars and lorries and by the use of high pressure tyres on heavier vehicles. The difficulties of the road engineer can be realised when it is known that it is possible .for corrugations to be developed by the passing of 50 vehicles over a gravel road at 40 miles an hour. Many of our unsealed highways carry up to 400 motor vehicles per day."