CONCRETE HIGHWAYS

Dominion, Volume 28, Issue 99, 21 January 1935, Page 11

CONCRETE HIGHWAYS

Seaview Road as Good as Any in New Zealand SOME COMMON ILLUSIONS

Some factors to be taken into consideration in comparing the surfaces o paved roads to-day with those of several years ago, and also a few of the illusions that had to be guarde against in making comparisons, were mentioned by the assistant city engineer of Wellington, Mr. F. N. Thompson, in an interview with “The Dominion”, on Saturday. Some motorists claim to have noticed corrugations in the concrete section oi Seaview Road, but Mr. Thompson said that actually the road had altered very little since it was laid down. _ The instrument used for testing the riding quality of a road is called a rougaorneter, and at the time Sepview Road was put down and after it had settled it gave a roughometer reading of about GO." It had returned almost exactly the same reading in. a test only a day or so ago. Since that road was laid down the authorities had gone in for pavements planed on top, and the effect'was that there were pieces as smooth or smoother than Seaview Road. 'When it was put down Seaview Road gave what was considered a perfect reading, but it now rode no better than most oi the surrounding roads. Without the use of a roughometer the difference between roads giving readings of from about 40 to 60 Could not be detected. They all rode very weil. Owing to the more modern type of car and the smoother surfaced roads average speeds were higher than previously. The roughometer purported to give the number of inches (degrees) of roughness in a mile on a car going at 25 miles per hour. Naturally in speeds higher than that the reading would be higher. Another factor was that a few ot the bitumen expansion joints, as a result of the long spell of hot weather, had tended to squeeze up. although this disappeared again in the winter. Only about one joint in <en showed tinttendency but some of them gave quite little jolts. Seaview Road had given a reading of 50 when it was put down, and 60 shortly after, when it had settled. It had remained practically at that figure ever since. Seaview Road was as good a bit of concrete road as there was in New Zealand. Mr. Thompson also corrected an impression that the two-mile section of the Hutt Road southward from Petoue was not as smooth as the Petoue Parade. The Parade bad a rouga* ometer reading of 70 and the other section one of 45. Getting below 100. in pavement work represented something of a revolution in road construction. Another illusion to be guarded against was that while defects in pavements were rarely of any appreciable per eent. this often gave the impression of general failure when it was not so. , . One of the factors to be contended with in the use of slow setting materials was that the wind tended to form a layer of dust, and the dust helped in parting the niix. The authorities were now using a planed on mix which required. 24 hours manipulation, and ! t was giving good average results.