THE BITUMEN ROADS.

Hauraki Plains Gazette, Volume XXXVI, Issue 489, 21 October 1925, Page 3

THE BITUMEN ROADS.

INSPECTION BY COUNCILLORS. • FAULTY FOUNDATIONS. An inspection of the bitumen-bound roads around Turua was made by members of the Hauraki Plains County Council last week. It will be remembered that shortly after the arrival of the present county engineer he reported to the council that there was insufficient funds to carry out the work in a proper manner, and that he would not have any work done below the recognised standard except by specific direction of the council as otherwise, if the job proved a failure, the blame would be attributed .to him. The council then, by resolution, instructed the engineer to cut down the quantity of metal, to be laid on the roads in the Turua-Netherton roads- loan area so as to make the available loan money complete the undertaking. The inspection last week proved to the councillors the folly of having bitumen-bound roads put down on anything' but the very best foundations. The places where there was plenty of metal on the road before it was ■ scarified and on those places where the Originally stipulated depth of metal was used, the, load was found to be standing satisfactorily, but on those portion where the depth of metal had been reduced and where there was very little metal ( on the old road, and many deep mud holes, the -road was found to be cracking, and in some places breaking up. The fault was proved to be the failure of the foundations, .and had nothing to do with the bitumen, because at many places, probably where .there were originally deep mud holes, the surface was found to have tsunk and only slight cracks appeared in the surface. Where the cracks are not yet so wide, as to let the water through repair will be easy, and will, be carried out as soon as the weather is suitable. The depressions, will be filled with a mixture of metal chips and bitumen, and this will probably be all that will be required, as the foundations are not likely to sink further as long as water is kept out. The same process will be adopted at those places where the rupture i. is worse, but repeated fillings may be "necessary.

> In the town. board area there is a section of road that was originally intended to be 12ft wide, but when it was seen that the county road adjoining was 15ft wide instructions were ‘ given to make this road the same width by spreading the metal thinner. The work was done by contractors, who, when it was seen that the work was a failure, agreed to lay another two, inches of metal 9ft wide and coat it with bitumen.

The whole ’ inspection proved the necessity' of having nothing but the best foundations before going to the expense of bitumen-sealing. Where the road has a good surface; and has been down sufficient time for all weak places *o have shown and been, repaired until they are no longer weak, the best method to be adopted before bitumen-sealing is to scarify just so lightly that the new metal will bind and not Lie like a mat iJeep scaiifying may disturb the foundations to such an extent that no amount of rolling will make them as solid as though they had not been touched. ■ The- 'councillors were convinced that it is not wise tq have a road bitumen-sealed until the metal, has been down for some years, and that ■after the work had been completed some •maintenance may be necessary for the finst year. The drying of the subsoils may cause a subsidence, but 'if the' cracks are healed in. time the first subsidence will be the .last. If there were sufficient money available it would pay to raise al(l roads well above the surrounding country to ensure proper drainage of ihe foundations. ”