CONSTRUCTING A RAILWAY

Taranaki Daily News, 25 November 1926, Page 13

CONSTRUCTING A RAILWAY

THE ENGINEERING PROBLEMS. WORK ON THE STRATFORD LINE. LIFE AT TANGARAKAU. (From Our Own Correspondent.) Tangarakau, Nov. 22. The matter of cost will always "be the dominating factor in railway construction in New Zealand, at least for many years to come. In a young country, which is little more than scratched with railroads, and where the limited number of the population stands as it is, with no material alteration likely for many years to come, the matter of taxation has at all times to be considered. Just how much the people are able to stand, and when it is considered that it takes years for these lines to become revenue producing against the capital outlay, it will be the better realised that the engineers’ greatest difficulty is cutting his cloth to suit the measure. And so it is not always apparent to the mind of the layman just why the engineer substitutes a filling for s' bridge, or makes a cutting where a tunnel might appear more suitable, and it is just here that the data which the engineer has at hand which shows the difference in the ratio of the cost of a tunnel and a cutting or a bridge or a filling, all going to show that *t requires the engineering mind to sift out the cost, length of time to construct, material available, and formation of country traversed, and then there is always the unknown quantity. It was this latter aspect that caused a halt in the boring of the great Simplon tunnel, where the diamond edged picks had to be used to get through a seam of some granite-like formation. There is also a verj- important factor in railway construction work in any country, and more particularly in New Zealand, that of the transuort of material preparatory to the work being started, and that of the housing and feeding of the personnel required over a lengthy period. To cope with the urgency of the work in hand the engineer must perforce concentrate simultaneously at different points of the proposed route, and it is here that the length of time it would take to transport hundreds of tons of cement and iron over a precipitous jig track, as well as the cost of the material itself, and the man power required, has to be taken into consideration. It is all a matter of overhead charges, and so wher the engineer finds he had good bush timber riglrt on the site he uses this in making a temporary trestle bridge, empties the spoil from'a cutting (which he might otherwise find hard to dispose of) over the side, and so you have the reason for the filling in place of a bridge. From Tahora and Tangarakau to Mangaone the length over which the works operate at the present mbment, the matter of transport seems to be the chief difficulty. After leaving Tangarakau flats there is nothing but a procession of mountains and valleys for a distance, of some six miles or more, where easier country is reached. The first big tunnel is close on a half-mile long, and here the cream of New Zealand’s tunnellers are working in shifts night and day, boring, blasting and cementing at the rate of one and a half chains per montji. Compressed air drills are used in the boring and ventilation plant installed to take off the exploded gelignite fumes before the men re-enter the tunnel. The piercing of this tunnel will eventually open out overlooking a very deep valley, and this at the moment is being spanned by a

temporary trestle bridge by expert bridge-men to a height of some eighty feet which will connect on the opposite side with a tunnel already pierced, which is being converted into a cutting by the insertion of three shafts along the top, and the spoil used in the filling of this valley route. From here onwards the permanent way is well forward in the course of construction for a distance of quite half a mile, where it will enter a big tunnel of over a mile in length, and now on the point of being started beyond which it will open out on to Mangaone. A large power house in the camp supplies the electric current for hauling and air purposes, and in great measure helps to solve the transport problem. Further afield a great deal of the material has to be packed with man power up hill and down dale, carrying timber, rails, sleepers, tents, stores and all manner of material in this big push. Steel aerial cables are cleverly rigged over deep valleys, over which is hauled the heavier material, which, in turn, is trucked on to where required. There is a post office in the camp, and the staff handles quite a considerable amount of business, but I’m afraid if the continued spell of bad weather continues withdrawals will very much exceed deposits in the savings department of this branch. The other day a fellow here asked another how many chains of fencing he could do in a day. The other fellow said he laid that much one day it took him two days to get hack. Exit!