A COSTLY TUNNEL

Wanganui Chronicle, Volume 72, Issue 1, 2 January 1929, Page 12

A COSTLY TUNNEL

TWENTY MiLES OF ROCK GREAT NEW YORK UNDERTAKING NEW YORK, Dec. 12. A tunnel. 20 miles long, is to be drilled through solid rock 5001’t beneath the surface of New York City. It will take about six years to complete, and the final cost will be about £12,000,000. This will be the second great water supply tunnel to serve New York. 'The <-ity’s tr; will not be disturbed by the construction of the tunnel. Fifteen working shafts will be sunk, and sections will go out laterally. The shafts present special engineering problems. Pneumatic, caissons will be thrust down through water-bearing earth to the rock. Within them excavators will work und°r air pressure. The direction of the tunnel is I;?,ed scientifically, so that, when the h. :-.<L ings arc about to moot two rifle shots fired through the earth from cither side would hit & half-crown piece buried in the centre. The fumes of subterranean blast explosions will be driven by compressed air to tho mouths of the shafts. Conveyors will carry the debris to trucki drawn by electric mules to the elevators. The tunnel plans provide for its ultimate extension across f he harbour. On the question of how long it will last, the chief engineer of water ropply, Mr Thaddeus Merriman, says that, about 2100 years ago, the Roman Emperor. Hadrian set the slaves of Athens to build a tunnel as long as this one. They had more rudimentary tools. Blasting -was done by building.a fire against the rock, then dashing vinegar against the heated solid rock. Their tunnel is still carrying the water that Athenians use for bathing and washing.