OTIRA TUNNEL PIERCED

Dominion, Volume 11, Issue 260, 22 July 1918, Page 6

OTIRA TUNNEL PIERCED

By Telegraph.—Press Association. Christchurch July 20. Advices from Oura suue that the Oura tunnel was pierced this morning with' an iron rod eleven feet in length. The successful piercing pf tho tunnel murks the Iriuiupli of no mean engineering feat. There were no unlooked-for troubles in the cutting of the hole under the mountains, although it was upwards fit fivo miles long, but to ensure the meeting of the two headings exact surveys had to be made in country very broken and difficult to survey, and exact calculations had to be made upon tlio surveys. For tho accuracy of these operations the Chief Public Works Lngineer (Mr. H. W. Holmes) and his 110fessional staff deserve much credit. The joining of (lie two headings means that the two ends have met for practical purposes exactly. In tho cuttiog of a tunnel it is never , the practice to carry in a heading of the bore of the tunnel when completed, but only to cut a drivo just large enough to allow of the spoil being taken out in email trucks. Other gangs of 'workers far behind tho first heading widen out tho tunnel to the required size, and Topare it for the lining which it must have before it can be v.sed. There are in the two lengths of heading oil either s ; de of this tunnel—at the Bealey end end the Otira end—about a mile and a quarter of the small heading, so that it 11 ill be tho easiest mattei in the world to straighten out a few feet: of error, should this be needed, in cutting the tunnel to full width. The piercing of the tunnel means that the preliminary surveys voio faultless. Of course, such a long tunnel would 'be impracticable for steam locomotives. It would not be possible to ventilate it. No engine crews could drive through it, and certainly no passengers could survive such a journey. Hails would be corroded rapidly by the fumes of the locomotive furnaces, for these i'lmes would never be out of the tunnel. It . has always been the intention to nso I electric power, and there are one or two I schemes for the production of current bv. ■water-power obtainable in the reg'on. I