BITUMINOUS PAVING

Evening Post, Volume CXI, Issue 37, 12 February 1926, Page 10

BITUMINOUS PAVING

ENGINEER DEFENDED

FAILURE OF THORNDON QUAY

DISCUSSION BY CITY COUNCIL.

The failure of bituminous paving in Thorndon quay and elsewhere in the city and suburbs was discussed at. some length by members of the City: Council last evening, and opportunity was taken by Councillor ' H. i>. Bennett to defend strongly . those officers of the council whose work had been criticised in the columns of the Press and also round the council table. That mis- ■ takes had been made was admitted, . but, compared with the total area concerned, the amount of failure w» extremely smalLj It was to be recognised, said the Mayo* (Mr. Norwood), that the Wel-lington-City Council had largely been pioneers in bituminons paving, and when one considered the enormous area laid.down there was but a very small percentage of failure. Where there had been trouble very careful investigations had been made, and every endeavour made to ascertain the reasons. In the question of formulae various considerations arose, and it was apparently M a result of a shortage of fineness in the sand need that trouble had developed,in Thorndoa quay. None of the officers of the council had been sest overseas to study methods of laying down bituminous paving, and under the . circumstances it was not surprising that in deciding theoretically what formulae should be used some mistakes should, be made. COST OF EEPATRS. : The cost of repairs, continued Mr. Norwood, in reply to Councillor Aston, would be made known to the council at its next meeting, but as against any form of maintenance that had been a huge saying. In several cases of'failures the engineer had reported, prior to laying down the pavement, that there was a possibility of failure, but by proceeding with the paving, anticipating a- possibility of failure, and returning to carry out what repairs might become necessary, the roadway had been kept open, and given, generally, a good surface for traffic. ..

Councillor Semple asked whether temperatures at which the pavement n laid might not have had something to do with the failure of the Thorndon quay serf see. Upon that point, replied the Mayor, there might be a difference of,opinion, bat he considered that the engineers had been justifies in reaching the con-^ •lusion which they bad. It had been suggested to him, said, Councillor Semple, that the care which had been exercised in the laying of the Hntt road pavement had not bsen eiereised in Thorndon quay. WHAT OF THOENDON QUAY? Councillor W. H. Bennett said that probably what had happened in Thorndon quay was that the sand' had prevented the paving from setting. The fact that the wrong sort of sand had been used was the primary cause of the Thorndon quay failure. Councillor 6. A. Troup said that he understood that they had machines to grind the sand as fine as possible. The Thorndon quay experience decidedly disquieting. He quite understood that they had to make experiments, but why should they experiment over raeh a long strip of road. Their main consideration seemed to be speed and sot the soundness of the foundations. If the foundation was not sound they might as well not build the roads. Past failures did not concern the council so much as the fact that they indicated what might be expected in the fatwe. Were they to understand from the engineers whether the failures were isolated eases, or whether they were the beginning of the end? Councillor M. F. Luekie. expressed surprise at Coutfcillor Troup 's remarks. Everybody knew that the foundation was the important feature, but the fact, was that the foundation of Thorndon quay was as good to-day as it was when it was laid down. It was the surface which was at fault, and councillors ahovld make themselves acquainted with the facts before they made alarmist statements. An authoritative statement should be made concerning the whole position. OOUNCILLOB BENNETT MAKES A STATEMENT. Councillor H. D. Bennett made a statement at the invitation of the Mayor. It was a most regrettable thing, said .Councillor Bennett, that coundtian should decry the worth of their officers. If councillors realy felt what they .were saying about the condition of the pavement the council was laying down in the city and suburban districts, they should take steps to dismiss tile officers concerned. That, was the step he would take if he felt half as njneh as was apparently felt by some of the speakers. His heart went out to those officers. As the Mayor had stated, paving-was a new work; they had to make experiments and .they were the pioneers in New Zealand* For those who had taken an'interest in the work —and he was one—it had become a most pleasant revelation to find that so much- good work had been done. Tfcey started oft with one plant, and had brought a man from America to give them the lead. They had made a start with the Hufct road, and there was no one to-day who would say that it' had not been a success. -Questions were raised as' to the accuracy or otherwise of the figures published by the council as to the cost of the road, bot those figures had, now been acceptted as substantially" correct. HXBTOBT OF THE WOBK. They now heard from some sources that the work they were doing now was not as good as' the standard set by the Hutt road. 'There had been difsealties,. of course. They had' voted a sum of something over £300,000, and had started off with one plant. Since then they had secured three other plants, and they had had to break in fresh men to do the work. Hot mix pavement carried with it quite a lot of delicate work, in weighing out ingredianta, and the plants required the services of quite a number of men who had to exercise control over very defieate instruments. The plants were ecteulated to run out a mile to a mile and a half per week, taking the capacity of the plants as a standard. He was glad to say that they had on one or two occasions gone past the mile per week. It might surprise Councillor Troup to learn of the huge extent of the paving which had been carried out by, the Engineers' Department since they commenced work and it only remained for councillors to inquire into U>« extent of the faulty work to find what a miserable thing it was in comparison with the work which had been done. Councillor Bennett said that he eou}d read a long list of streets which had been paved and in which it had ■ot been necessary to carry out reKXRHJiDIT UHE TO DATE* The total expenditure to date in connection with paving had been £150,----000, and 25 miles of paving, with a filament of 24 feet, had been carried out. The faulty work in Thorndou quay amounted to 1300 square yards, which, at a cost of 5s 6d per square yard, would cost £370 to replace. It iras estimated that the total expenditure on repair work would amount to £1500 or 1 per cent, of the whole. Surely that was a matter for con-

gratulation. What was the Press criticising? What were they, wanting? If that section of the' Press which was criticising the council would bring forward some constructive criticism the council would reply to it. The whole of the information which he had collected was available to other members of the council. PAST THE PIONEERING STAGE. He did not want to hide their faults, said Councillor Bennett, they had difficulties in connection with the work. They had been pioneering, but now they knew more about the business and should be able to lay down pavement which would not' have to be pulled up. They had experimented on one side of the Thorndon quay, and they would nowhave to pay for that experiment. They co^ild- rectify that mistake for the paltry sum of £370, and they could guarantee that.the repair work would stand. . He felt quite certain that the repairs would be all right. They must be prepared to find further faults, but these would be remembered as they occurred. A CEISIS. Reference had been made to the misunderstandings and differences which had occurred with the Highways" Board, said Councillor Bennett. They had reached a crisis while the Mayor had been away. They fell out with the Highways Board, but ncit because of the faulty nature of the ingredients of their mix. The stuff they put in was absolutely good, but some objection was raised by the Highways Board at the, grading of the different sands and the proportions of various materials put in. That and that only had been the cause of the trouble. The mix, it was found, was not coming up to specifications. Unless these faults were 'corrected, it was pointed out by the Department, the Government could not be expected to pay a subsidy towards/the cost of j the work. That brought about the crisis. A conference had been held, and at this officers of the Public Works I Department and officers of the City Council had conferred on the matter. The result of ,that conference had been that that the whole of the matter had been cleared up, and satisfactory arrangements had been made regarding the ingredients to be put intr the mix. He would like to point out that the specifications required by the Highways Board were exactly the same as they were putting in in Wallace street to-day. ( BEMABKABLE WOBK. The Engineer's Department had done remarkable work, said Councillor Bennett. He • had extracted a statement from the Public Works Department that the pavements that were being laid down . in Wellington were superior to anything put down in New Zealand, including the concrete roads in certain parts of the North Island. He had been surprised that the City Engineer had been able to stand up to the criticism which had been levelled^ at him, not only by outsiders, but by councillors, as well. : ...'.-..-.'