JuLV 4, 1 90 1 



NA TURE 



235 



THE SIMPLON TUNNEL. 



FEW undertakings have had to encounter so many 

 difficulties as those which have impeded the con- 

 struction of the Simplon Tunnel. Apart from the purely 

 mechanical scheme which proposed to cut a narrow space 

 in a definite direction through hard rock for a distance of 

 some 20,000 metres, at a considerable depth below the 

 surface, and the difficulties of a physical character 

 connected with temperature and sanitation, there must 

 be added financial considerations of a very onerous 

 character, possibly increased by the subtle and con- 

 tinuous opposition on the part of existing interests. 

 That all difficulties, save, of course, the actual labour 

 of tunnelling, have gradually disappeared speaks elo- 

 quently of the energy and mechanical resource displayed 

 by the engineers, and of the policy and address e.\hibited 

 by the management. Rumours have appeared now and 

 again in the newspapers of strikes among the workmen 

 and of delays arising from 

 that source ; but such incon- 

 veniences have always to be 

 anticipated in long-continued 

 workings owing to the gra- 

 dual changes that occur in 

 the condition of labour. Such 

 annoyances may delay the 

 completion, but they cannot 

 prevent it. 



We commented on some 

 of the difficulties and some 

 of the advantages attendant 

 on the construction of the 

 tunnel in a previous article 

 on April 20, 1S97, when the 

 project had entered on the 

 stage of a practical under- 

 taking. Four years having 

 passed since that time, it is 

 not uninteresting to review 

 the progress that has been 

 made, and see how far the 

 ingenuity of the engineers 

 has triumphed and what 

 prospect there is of a com- 

 pletion within the term ori- 

 ginally assigned. The con- 

 tract for the construction of 

 the tunnel was signed by 

 Messrs. Brandt, Brandau 

 and Co. on August 13, 1898, 

 but this firm stipulated for 

 three months' grace before 



boring operations should commence. Consequently, No- 

 vember 13 is the date from which the five and a half 

 years demanded for the construction of the tunnel is to be 

 reckoned, and the critical epoch will be May 13, 1904, 

 when a fine of 5000 francs a day will be demanded from 

 the firm for the non-fulfilment of the contract, or a 

 reward of similar amount be paid to them for the earlier 

 completion. Practically, 2000 days have been assumed 

 as sufficient to bore through 19,734 m. of rock, con- 

 sequently the average daily progress should be 9"86 m. 

 Of course, this perforation applies to the distance 

 traversed at both ends, because the work really consists 

 in making two tunnels of approximately equal length, 

 whose ends shall join in the middle of the mountain. 

 From data supplied in an article by Herr L. Ernst in 



daily maximum of 6'5 metres. But on reaching the 

 gneiss, of which the general mass of the mountain is 

 composed, the workmen had to content themselves with 

 a daily average of 5'2S metres. But on January i, 1901, 

 or 769 days after commencing operations, a tunnel of 

 41 19 metres actually existed, and this gives an average 

 advance of 5 '4 metres daily. On the south side, owing 

 to some difficulties with the Italian Government, who 

 objected to the employment of dynamite for blasting 

 operations, the boring machines did not get to work till 

 December 24. Further, a much harder stone had to be 

 penetrated on the southern side, and the daily progress 

 was only 371 m. ; but the employment of more efficient 

 water power has raised this slow advance to 4'5 ni. 

 Effectually, a tunnel of 3148 m. had been bored by 

 January i ; and this gives an average progress of 43 m. 

 Clearly, therefore, the daily advance at the two ends is 

 slightly behind the anticipated amount by o'26 m., 

 but by the removal of initial difficulties and greater 



Workshop in Brieg, Switzerland, at the foot of the road leading 

 foreground are two boring chisels mounted on one stand. tFn 



experience on the part of the management, this slight 

 deficit may be wiped out. 



\'ery considerable modifications have been introduced 

 in the form and manner of working of the boring 

 machines. In the earlier constructed tunnels the 

 boring chisels, faced with diamond, cut their way into 

 the rock, the motive power being compressed air, the 

 compression being effected by hydraulic machinery. 

 Herr Brandt recognised the loss of mechanical power in 

 this arrangement, and decided to use water pressure direct 

 on the boring apparatus. At the same time he dispensed 

 with the diamond cutting process, which, by means of rapid 

 rotation, worked its way into the stone as a saw, substi- 

 tuting a hard steelface to the chisel, which is driven against 



^^ .„ ^ _ the rock and rotates slowly, about six times a minute. 



Die Uinschau for April 13, it is easy to compare the The boring tool is made hollow, and the detached frag- 



actual advance made at either end with the daily average 

 that the contractors hoped to make. The attack on the 

 north side was begun on November 22, 1898, and at first 

 the boring machines encountered a tolerably soft stone, 

 and the progress was proportionately rapid, attaining a 



NO. 1653, VOL. 64] 



ments collect in the tube and are expelled by water power. 

 Two boring chisels are mounted on each stand and are 

 worked simultaneouslv (Fig. i). The aperture of each 

 borer is 10 cm., and is driven into the rock a distance of 

 2 m. Into the aperture thus formed a cartridge of 



