A THIRTY MILE RAILWAY TUNNEL.

Wanganui Chronicle, Volume LX, Issue 16949, 10 April 1917, Page 2

A THIRTY MILE RAILWAY TUNNEL.

Not so very many years hare passed since the time when the proposal to build a two track railway tunnel 30 miles in length beneath one of the great mountain ranges of the world would have been thought preposterous ; but m these days of big engineering achievement, the question of mere physical magnitude is often the least serious element of an undertaking.

During the development of the great railway systems of the world there has been a marked -increase in the cost and time of construction, of the long tunnels which,were ne-» cessary to carry the lines across the various continental divides. The most important of these tunnels, at least in respect of their length, are to be found in Europe, more particularly in the Alpine regions, ar.d the following derails as to their length and the rate of progress in their construction are illuminating. The first of 'these, the Mont Cenis, built in 1857-1871, is 7.5 miles i\ length, and the rate of progress was 7.75 feet per day. Then came the' St. Gothard, 1872 to 1881, 9.5 miles in length, in which the rate of progress rose to 18 feet per day. The Arlberi tunnel, 6.5 miles in length, built in 1880 to 1884, was put through at the rate of 27.25 feet per day. The Simplon tunnel, 1893- to 1899, 12.25 miles in length, was built at the rate of 36 feet per day; and the Loetschberg tunnel, 1906 to 1911, 9 miles in length was built at the same rate of 36 feet per day. :

It is now proposed by BrigadierGeneral H. M. Chittenden, U.S.A. (retired) to drive a two track tunnel through the Cascade Range- of mountains, which will be 3 0 miles in length and have a summit elevation not much over 1000 feet above sea level, the object of this great work being ,to give a short and easy cut to' Puget Soiund and the gre?.t seaports of the north-west, and avoid the serious interruptions and disastrous accidents which have occurred of late years on the present high level railroads across the mountains. ]

Regarding the cost and time for construction, the writer bases his estimates on the experience had with the double track Rogers Pass tunnel through the Selkirk range on the Canadian Pacific Railway, which is now nearing .completion. Progress has been at the rate of about 52 feet per day, which it shoul he noted is a striking advance' on the rate in .the Simploh and 'Loetsehberg. tunnels through the Alps. To expedite the work, : four shafts : from I*loo feet to 2,320 feet ii depth, would be sunk along the; line of i>he tunnel,; and it is estimated that with these four shafts the 30 miles of tunnel could be put through in five and a half years at a total cost of 43,237,000 dollars. '

As to; the operaing advantages, the Great Northern Railway would abandon its present railway over the mountains, which has gradients as high as 2.2 per cent, and takes three hours for passenger trains'and ten hdurs for freight trains to traverse, and in its place would have a nearly straight and level line, free from risks, and with a passenger time of forty minutes and a freight time of an hour and a half. The. Northern Paoifio route ' would bo reduced 90 miles in length and. 1,850 feet invertical lift, while the average saving of distance, for the Union Pacific would be 180 miles by one route and 140 miles by another.