THE MIDLAND RAILWAY.

Otago Witness, Issue 2809, 15 January 1908, Page 38

THE MIDLAND RAILWAY.

[« j THE ARTHURS PASS' TUNNEL. n j (Faon Otra Own Cobeesfondbnt ) v * xr xt °?^ TOB -WVB> January" 10; ;o ! Mr Neil M'Lean, one of the contractor* c ' for the Arthur's Pass tunnel on the "\Fd- , r i land railway, was in Oflriatcfiurch- to-day 0 | passing through on- iris- way to- Ofcihr. Speakis |m S t° / a representative of the Press -e-w-i gaming the progress of the work, Mr> . t ! M Lean stated' that he had- just received a n f cable messag©- from his brother ' (Mr Murt t doch M Lean) that he- hadV purchased anIngersoll Rand- air drill, winch would he "used in- the boring opera±ions..at th& tunnel. In making this selection he had heen. guided by, observations, made* personally on the Continent and at Home; where he- hod; seen . both, the Ingeraoll Band air drill r. and various, makes of hydraulic drills afef work in- tunnel construction. While n» f , Switzerland Mr M. McLean made «, visit; 3 to the Loetschberg tunnel (eight and a-hal£ f miles)y which is being- constructed betweea > Briguo and Berne, and in which the a.iv . drill is being used with satisfactory results. r The contractors were driving, the drills with. 3 electric motors, 'the power being ' generated!. $ by water and supplied free. The Loetsch1 berg runnel -is only.. 20' miles from th e> i famous __ Simpkm, which was driven with i hydraulic, drills, ea the adaption of the' s air drill in, the new work in the face ' of ! such a notable example" would, appear ro ► prove that the contractors'' were- satisfied - that the air drill was superior. As" a martter* ; i of fact, much less power is required, andT -" the trouble, with water (inseparable front . the hvdraulio drill} iB entirely obviated. • i ,• Mr M'Lean estimates tha*- 200 h.p. -will" 1 be required- at^ each end ofr the" tunnel to»" . drive the drills-. At the- v ßealey . end the>/- • Punch Bowl Palls will be harnessed, andh ; it is' estimated that 760 1 h.p. will be generated. At the Ofcira end 1 one of the streams, will be utilised, and 1 500' h.p. will be avail- ' able. In- both cases' the- power will bat generated' at the- source of supply- amj conveyed by wires to< the tunnel working. In the Loetschberg tunnel the drills arebeing used to drive- a " heading" along 1 the line followed by the tunnel before the"widening out" to- full 1 size- is 1 started. This method will also- be followed in the- ■ Arthur's Pass tunnel to" tne extent that the labourers engaged- on that task will not be. - ', worked close up to the drills. The idea 1 is to interfere as little- as possible with the advanced work, «_aa any appreciable* accumulation at the rear is- liable to causa delay in getting the- Jrilled-out material away. In regard to the ventilation of tha i wordings, where the headings are advanced 1 sufficiently to necessitate; a plant being* put in, _ the system of exhaust will be adopted in preference to air' being forced , in from the tunnel's mouth. The exhaust system is generally favoured" on the Continent, as it draws out the foul air, and freshc 1 air rushing- in, Nature abhorring a vacuum. i It has been found that to foree 1 in,freshr air only removes the foul atmosphere from* the face, and' that the work cannot ba properly ventilated in the- deeper recesses of the headings. At the Otira. end Mr M'Lean says about; 50' huts have been erected, and carpenters are now building th©, workshop, while labourers are doing bush clearing at thtfe' tunnel mouth. He expects to start with the cuttings next -week. Sa.< far- nothing .has. been done at the 'Bealey end', and' probably a start will not< be made" until Mr Murdoch! M'Lean returns. Mr M'Lean is finding no difficulty in' getting all -the labour he requires at present, and he receives numerous • applications for work., '"Of course," he ' said, "I don't know what it will be like I later on, but I think that with a good long jofe offering at 10» a day and _no _ lost tun©" there should be plenty of applications." WELLINGTON, January 9. Mr G. M. Fraser, who built the steel v bridge over the Waikato River at 'Camj bridge (the only one of the kind in Aus- ! tralasia), has come to the capital to confer with the Public Works Department regardiing the' contract he has secured for the 4 erection of the Midland railway viaduct over Sloven Creek, 15 miles from Springfield. The bridge, which will be of steel, will be 600 ft long. The preliminary excavations have been started, and the steel workers are shortly expected from. Home. The contract price is £21,400.