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THE SIMPLON TUNNEL.
THE LONGEST RAILWAY TUNNEL. THE WORK ALMOST COMPLETED.
[By Cable.] LONDON, October 11. The Simplon tunnel is complete except for a length of 244 metres (neariy 207 yards). Latterly boiling springs have im- peded the work, but refrigeration has been used with success. [Mr. H. G. Archer, writing in the Lon- don "Daily Mail," says : — [The boring of the Simplon tunnel, the longest railway tunnel in the world, is on the eve of completion. [Any day now we may hear that the miners descending from Switzerland have joined hands with those ascending from Italy, while there is reason to believe that when the meeting takes place the maximum error of direction will be only two or three inches outside an exact coincidence. There will then, of course, be a lapse of many months before the railway can be opened. [The enormous advantages of the new tunnel are apparent, it will win back to France much of the international traffic which has been lost to the railways of that country since the opening of the St. Gothard and thus will inflict a heavy blow to the German railway interest ; but, at the same time, it will convert Genoa into
a formidable rival to Marseilles in respect of Swiss imports. It will effect a consider able saving of distance between the Straits of Dover and the Adriatic, and so will be chosen the Eastern mail route as between Calais and Brindisi. Lastly, where traders are concerned, it will prove a more econo- mical route than both the Mount Cenis and St. Gothard because its conditions of grade are so much more favourable. [The Simplon is tie fourth Alpine tunnel and the second between Switzerland and Italy. The direction of the tunnel is prac- tically due north and south, from Brigue, on the Swiss frontier, to Iselle, on the Italian, or from the Rhone Valley to that of the Diveria. [Hitherto the only means of communica- tion between the two valleys has been by road through the wild, beauiiful, yet, even on the brightest day, gloomy pass in the Lepontine Alps. The Simplon Pass has been used as an international thorough- fare since A.D. 206 ; but the construction of the magnificent road, which still de- serves to rank as one of the world's grand engineering features, was undertaken by Napoleon and built between the years 1801 and 1803. [The road from Brigue to Domo D'Ossola is forty-one mils in length and attains an altitude of 6590 ft. The route taken by the tunnel keeps to the northeast of the road, stringing the bow as between Brigue and Iselle. The mammoth bore is 12 miles 458 yards in length, and for seven miles is in Italian territory. The St. Gothard tunnel is 9 miles 564 yards long, the Mont Cenis thirty yards short of 8 miles, and the Arlberg 6 miles 404 yards. Each of these tunnels accommodates a double track, and the dimensions of each are, roughly, 21 ft. in height by 27 ft. in width.
[It would have been possible to make a shorter Simplon tunnel ; but a tunnel at a higher altitude would have involved steep approaches, and the lesson inculcated by the three Alpine tunnels already con- stricted, is that cost of the haulage of the trains up the gradients nullifies the initial saving effected by making the per- foration as short as possible. Howerer, the Simplon tunnel at the northern portal is only 2254 ft. above sea level, or on the same level as the rails at Brigue station, a mile and three-quarters away, whence it ascends for 10,004 yards at the gradient of 1 in 500 to the summit level of 2313 ft. It continues level for 546 yards, after which it descends at 1 in 143 for 11,028 yards to the Italian portal, which is 2080 ft. above sea leveL Immediately on entering at each portal there is a short curve. Otherwise, the tunnel is dead straight — namely, for 12 miles 103 yards. [The Italian approach is very different from the Swiss. The extension of the rail- way from Domo D'Ossola hither is 20,419 yards long, with a total rise of 175 ft. Here there are no fewer than six tunnels, with an aggregate length of 8067 yards, and one — the longest — 3280 yards in Iength is helical : that is, the train will "loop the loop." the difference in altitude between the portals being 307 ft. [We have seen that the other Alpine tunnels take a double track : but the Simplon really consist of two tunnels, JJKK op.tb tjiUing v single track. This novel method of construction was decided upon owing lo the great length of the perfora- tiom ind its great depth below the surface. The depth of the axis averages 3740 ft. and it attains 7000 ft. in one place. The prob- lems were how to ventilate the bore both during and after construction and how to obvi^re llic r\ exeedinglv high temperatures which K-'.'iild be met with in the deepest
parts. rKfel.lly or wrongly, tile authorities de cMed il»M \bc for?gnir.jr problems might be solved liv dividing (l.i? work into twin sincle track tnnrrK rb~eJ SS ft. apart entirely rijsti'nct, s?w Hear the centre, wliere ttoy beenme oiw f--r a distance of 420 vuvi-s in order to give rwm for fidings amj'cro=b-r.vcr roads, but throughout they are intci-connt-otcti liv tran-versc galleries every 2* yards. The idea was that each tuned might act as a ventilating shaft for the -oOmt. Tc Lcgin viLh, Tiowever, only one tunnel, the eastern, would be given Hie normal section for a single track— I nainelv, maximum Iieizhl, IS ft.: maxi mum 'nidtli. 10 ft. 4 in.; and area of errss =rtiion. 2.10 square feet. The other tunnel world be fcuUt in. re duef^l .'eclion — natocly. S ft. high and 10 ft. ?widp — and remain sn till tbe gross traffic receipts dsiiuld tawil £312S per mile, Trlien it woul'j bo enlarged to normal sec tinn. Th-nks to t^-is arrangpment of tun nels. t!ie iraius wi'I always run* against a dra'JcW of frefh ahr. . [This wUtme mtis eluborated in 1S33, when the pf+sl'iBities of ^ecbric inaction, were yervjeuelr re-ilised*.- The latter is certain to be .fcloptdd jifide Ibe -tunnel «vmnHr or later, asd^hae Uus been seen-be-' fore ft -wobW liayeJjegjJ^Lmpl^r-aiid less., expensire-io have1 construcfei' one double txack tunneL Everything connected vitiL the wort of construction is effected by tfaicr ymeer, both tbe Chose and the
Diveria luiving been harnessed for the pur pose. Hiis motive power, which represents GOOD horse-power at each end, could be cflsilv adapted to traction. - (The strata, through which tie. tunnels have beat driven were esceedtngly hard, being principally gneiss and schist ; but the Tlrandt bvdraulic rotating drill was never beaten. ' This beautiful machine in disputably -demonstrated its superiority to all others, achieving a. rate. of progress equivalent to four or five times wjiat has ever ...been:, attained in British tunnels through sirnDar material. [No praise is too-Jugh for the eluborale and perfect tutnrc of the.mechanical,.eani: tary, and eodological arrangemenr£ nnder token for the welfare of the Simplon miners. . luride the tunnel the tempera ture, , which has been recorded to attain 121 deg. Kahr. on.the rock, is cooled, to a maximiim of .77 d^g. by meaxls of sprays of glacier -water, filtered before qse,,and re lays of fresh air, which are passed through spravs and -dried by wire gauze £oreens~be iore'raachinp-.tbeir objective.: TteE font air is exhansUd bv the- great fans supplying the fresh, to; ike volume Tot CO^DDO cubic. feel., per minu'e -. and horses, were 'early banished from the calleries, as Ae ex halations frr.ni their bodies vitiated the -tt- mosphcre.^ 1'erfect aunlarj- .arid laundry arrangements are found outside. ' - , . £The ti.Dtjracior? f or the. wbole polossal undertaking- are Messrs. Brandt, Braudau, and Co., «if Hamburg. Accordinjg-to the terms of a revised convention, tbe first tunnel must l;e ready for traffic and the second cantuleiedfin reduced section hv ibe 30th of April, 1903, in consideration of the sum of £3-13I-jOOO. Active opeiatiouswere comxnenced in August, 1S~-3, and havecon tinned - minterruptedlv night and day