Five-Mile Tunnel Bore.

Kaipara and Waitemata Echo, 11 December 1914, Page 3

Five-Mile Tunnel Bore.

4 RIVER'S COURSE TO BE CHANGED SO THAT WORK. MAY BE DONE. Soaring- to dizzy heights, and surmounted hy snow-covered peaks, I lies the Selkirk Range of moiin--1 tains in British Columbia. Through

Mount M'Donald, the largest of these, stretching its topmost- point i'Sfioft. above the sea level, it is (as already announced) the purpose of the Canadian Pacific Railway to bore what will be, when completed, the largest engineering undertaking of its kind on the North American Continent. It will be necessary, before starting work on the main tunnel, to change the course of the TUecillewaet River for nearly a mile of its course, as this mountain stream rushes directly over the point at which the big cut for the tunnel approach must be made. The river will be diverted to a new channel about :.5(»0 yards to the left of its present course, and gradually led back into the original bed at a point lower down. The Selkirk tunnel will measure, from east to west, five miles through with approaches of 1700 ft. on the west side and 1320 ft. on the east. The, advantages of this tunnel will be threefold. First, and by. far the most important, is the fact that the tunnel will lower the present grade of the road 54:5 ft., the approaches on either side having a one in 50 grade, and the tunnel itself a one in 100 grade, sloping west. Some idea of the magnitude- of this undertaking may be gathered from the facts that over 500 men will be given steady employment for nearly four years, and that it will take somewhat over 20,000 yards of concrete to enclose the tunnel. The portal of the tunnel will be' 150 ft. wide by 40ft. deep, and it will be v necessary to go down sdft. further before reaching the tunnel grade, so, owing to the fact that in the neighbourhood of 240,000 feet of gravel have yet to lie reI moved before actual work on the , big tunnel can commence, the steam i shovels will have plenty of work [ahead.