THE SIMPLON TUNNEL.

Lyttelton Times, Volume CXVI, Issue 14192, 15 October 1906, Page 6

THE SIMPLON TUNNEL.

The threatened collapse of the roof of the second Simplon tunnel will naturally prevent the regular passage of general traffic, but the weakness that has been revealed , need not involve the ma'in tunnel. The piercing of Simplon is the most stupendous recorded achievement in rock-bor-ing. The work was approved by Italy and Switzerland only ten years ago, and the workers from tbe Swiss and the Italian ends met in February of last year, having bored tire whole twelve miles in lees than, seven years. The St Gothard tunnel; though only nine and a half miles- from -end to end, took longer to bore, and the rate of progress on that magnificent work was regarded in its day as phenomenal. The Simplon tunnel, which is the longest in the world, consists really of two parallel tunnels-52 feet apart, and. connected by galleries. It is intended ultimately to- use both for traffic, but for the present only one of the bores has been arched and thoroughly protected-, the second being used for ventilation purposes only. It is- in this second tunnel that the roof is giving way. Tbe expense of cutting this ventilation passage to its full height and building up the arched roof no doubt deterred tho promoters from completing tho scheme, but the progress of the work must have led them to expect very serious slips and •’■oof troubles in tho unprotected passage. Unexpected rock faults were encountered towards the middle, and it will bei remembered that the

work was rendered difficult and dangerous by springe, hot and cold, that wore tapped as the bore was driven forward. These faults, whether they admitted water or not, threatened the security of the tunnels, and tho unfinished second passage, which has collapsed, according to the cable message, has no doubt suffered at one of these weak points.