CONCRETE POLES.

Wairarapa Age, 15 August 1928, Page 7

CONCRETE POLES.

WAIRARAPA POWER BOARD DISCUSSION REPORT TO BE OBTAINED An inquiry into the question of using concrete poles instead of hardwood poles was suggested by Mr. A. C. Pearce at the meeting of the Wairarapa Power Board yesterday. Other members said that concrete poles were being used and were giving satisfaction in a number of power districts. Mr. T. V. Moore said that in a discussion at their conference last week, power board engineers would only allow thirty years’ depreciation, cu concrete poles. The Resident Engineer (Mr. H. B. Keenan) said that in Switzerland they had been making concrete poles for the last fifty or sixty years. Those wore spun poles, with a hollow centre, and some of them, were ninety feet long. Experience in Taranaki and Waitomo, as well as in Marlborough, suggested that the poles of the future would be of concrete. When used at angles, concrete poles had to bo guyed or stayed to enable them to take the strain. Crushed stone had been specified by Mr. Olimie for making poles, but this material accounted for only 6 per cent, of the cost of a pole. The expensive item was steel. 'Mr. Climie had estimated that the board could make 400 poles at a cost of £3 12s 6d apieee, for ordinary high tension poles. No doubt, with proper organisation, they could get the- price down still lower. Mr. Pearce moved that the Secrot-ary-Manager and Engineer bring down a report with regard to concrete poles. Mr. R. J. King said that hardwood, though it lasted only for twenty years, might be more economical than concrete. The Marlborough board had an up-to-date plant and were in the happy position of having an engineer capable 'of making these- poles economically. They had a movable plant which was moved from one river-bed to another in different parts- of the district. No doubt their scheme would be satisfactory.

Mr. Pearce said he had been told that the Marlborough poles were absolutely satisfactory. Mr. Keenan said that Mr. Cummings, the Telegraph Department Engineer, had told him that the Department was giving up concrete poles because it had large supplies of silver pine, an.i other poles available at very low cost. They were quite satisfied, however, with the concrete polos they had manufactured.

Mr. W. Benton said the problem was to make the concrete poles waterproof Mr T. V. Moore agreed. He said that water getting into the poles by way of cracks and subsequently freezing burst the concrete. He instanced a concrete bridge the panels of which had been badly fractured in this way. In the course of further discussion, Mr. King observed that they should be very careful about launching out in this matter. Concrete poles were at an experimental stage, “and we do not want to be pioneers, -seeing that our requirements are so small.’’

Mr. Kershaw said that they were far from- being pioneers. AH that was proposed was to obtain information. In view of the small quantity of poles required by the board, it was admittedly a question whether concrete poles would pay.

Mr. Pearce’s motion was seconded by Mr. W. Howard Booth and carried, the officials being instructed to obtain information as to the use of concrete poles by other boards, and the cost of plant etc. necd(,l for their manufacture.