TAWA FLAT TUNNELS

Poverty Bay Herald, Volume LV, Issue 17236, 16 April 1930, Page 15

TAWA FLAT TUNNELS

PROGRESS OF WORK INSPECTION BY MINISTER Good progress is being made with work on the Tawa Flat railway tunnels, near Wellington, according to a. stato- ■ menb made by tbe Minister of Public Works, tho Hon. E. A. Ransom, follow- ’ ing an inspection of the undertaking. "The total length of No. 1 tunnel,” said the Minister, “is 65 chains, and the width is 24ft. From the southern portal, Hutt road, the tunnel has been enlarged and concreted for a. distance of 1 18 chains, also for a distance of 15 chains from the northern portal, Ngabauranga Gorge. There are now 26 1 chains of enlarging and concreting to 1 complete, the centre heading for that length having been driven some time ago. At the present rate of progress it is estimated that No. 1 tunnel will bo completed in about 12 months’ time.” The Minister mentioned that tbe small battery locomotives used for bringing the earth-laden trucks from the centre heading to the south portal had been supplemented by a locomotive which obtained its power from overhead wires, similar to those in use in No. 2 tunnel, and which was placed in commission on Wednesday last. Whereas the small locomotives pulled three to four trucks, each of which hold two cubic yards of material, the locomotives hauled eight or nine. NO. 2 TUNNEL. Referring to No. 2 tunnel, which is 2 miles 55 chains in length, tile Minister stated that from both ends distances of ten chains had been enlarged and concreted. Satisfactory results were being obtained from the use of the big steel profile in the concreting work. The walls were first battened and then the profile, which was 24ft. wide, and 20ft. high, was jacked on a gantry and placed into position. From tho compressed air guns tile concrete was fired into the space between the profile and the walls, and when tho mixture was set the jacks holding the profile were released and the profile moved along by the gantry to a further section ahead. “This is an advantage on the old I system,” said the Minister, “and it, saves the man-handling of heavy wooden moulds, and at the same time gives a better finish to the work. For tho holding of tho country before the,,concrete is placed, loin. by lOin. New Zealand timber is being used throughout.” CUTTING DOWN THE TIME. The Minister mentioned that an interesting feature of the method of attack in the second tunnel was tho driving of a pioneer tunnel, 10ft, wide and Bft. high, running parallel to and ahead of the main tunnel and 66ft. away from it. At, various points along the route little “side streets ’ had been cut, into the course the main tunnel would follow, enabling the, main objective to be attacked at as many points as was desired, besides the two ends. This method would, it- was intimated, save at least a year in the completion of the big I tunnel. Tho Minister added that ho had taken advantage of the. opportunity to investigate the complaints placed before him recently by the men, and to examine conditions on the spot.—Dominion.