TUNNELLING JOBS

Poverty Bay Herald, Volume LXIV, Issue 19376, 14 July 1937, Page 4

TUNNELLING JOBS

GOOD PROGRESS MADE PLANT INSTALLATION FACES WELL ADVANCED Though tunnelling work on the Waikokopu-Gisborne section of the East Coast Main Trunk railway may be said to be still in the preliminary stage, good progress .has been made recently towards a point at which the Public Works Department will have the main jobs in first-class working trim, and employing their maximum economic number of men.

The use of modern machinery for drilling, for evacuating the spoil, and for concreting will facilitate the progress of the work, and the formation of the country through which the tunnels are to be pierced holds no prospects of special difficulties. The adoption of the full-section method of tunnelling, for the three major tunnels, has been decided on in view of the solid formation to be dealt with, and at two of the main faces the preliminary work has reached a point at which the system can be put into operation almost at once.

In the smaller tunnels, and probably in the case of the Coast tunnel, one of the three major jobs of 1 the kind, the older system of driving the bottom heading through first and then following with a top heading, eventually breaking out into the full section of the tunnel as a last step before concreting the lining of the tunnels, will be followed.

Variation of Methods

In the Waikura and Coast road tunnels, however, the full-section construction of the-shafts will proceed, with the concreting following close on the heels of the tunnelling parties.

An inspection of the plant already installed on the section was carried out during the past week by Mr. N. J. McLeod, mechanical engineer to the Public Woi'ks Department, the inspection including the special Diesel shovels employed at different points, and the compressors and cementpumps either already installed or now ready for setting up at strategic locations.

The electric compressor at Torrie’s camp and the fitting shop there were given special attention by Mr. McLeod, as also were the Diesel compressors at the coastal portal of the Coast tunnel, and a larger machine of similar type which is now being installed at the Waiau Valley portal of the big Coast road tunnel.

A number of the smaller shafts on the Waikokopu-Gisborne section are now well forward, especially those in, the Tikiwhata Valley and along the open coastal section. New work recently commenced includes the opening of faces on the small tunnels adjacent to No. 5 and No. 3 camps in the Kopuawhara Valley.