NZASM Eastern Line Tunnel
WARREN and ROYCE: Contractor
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The NZASM tunnel at Waterval-Boven is probably the best-known and most famous of all NZASM structures. Not only is it an impressive masterpiece of design and engineering, but also the only tunnel built by the NZASM and the first in the Transvaal (Mpumalanga).
The tunnel formed part of the rack-railway system between Waterval-Onder and Waterval-Boven. It was surveyed by engineer SISSINGH and chief foreman Bouten, and was constructed by the firm of WARREN & ROYCE. Drilling and rock-blasting began from both ends on 18 October 1892. The power plant generating the compressed air for the rock-drills was situated on top of the spur through which the tunnel was being built, and until the 1980s the boiler which was used was still in its original position. The actual cutting and blasting inside the tunnel was done by miners who were experienced in this field. The tunneling went well without serious mishaps, and on 9 September 1893 the two work teams met underground. Before the end of the year the full tunnel profile was hacked out of the rock. When the centre and levels were checked in the middle of the tunnel they were correct to within fifty millimeters - a wonderful feat of engineering indeed, even by contemporary standards.
To keep the tunnel as short as possible part of the mountain on the eastern side was blasted away, whilst a huge cutting was made through solid rock at the opposite end.
On account of the instability of the rock it was necessary to line the tunnel with stone masonry. However, in order to reach Waterval-Boven as soon as possible, the rails and rack were laid prior to commencing with this work.
The lining was completed by May 1894. The walls and roof of the tunnel were extended on the eastern side to end in a portal filled back with rubble so as to catch loose rock and other debris in order that they be prevented from falling onto the track.
The completed tunnel had a length of 211m. Its construction was complicated not only because of this length, but also because it formed part of a curve with a radius of 225m. There was also a maximum gradient of 1:20 with which to be complied.
At approximately the halfway mark an arched niche was constructed on one side. There are numerous speculations as to the purpose of this niche - some believe it to be the beginning of a drain, while others even consider it to be the hiding-place of the fictitious 'Kruger Millions'! However, the purpose of the recess is really quite simple, as stated in the 'Rules and Regulations' for gangers: 'At the arrival of a train, should the 'ploegbazen' (gangers) and workmen working in a tunnel have no time to reach the recess constructed in the wall of the tunnel, they will lie down between the line and the wall'.
[De Jong et al, 1988:122&124]
TUNNEL ON NETHERLANDS-DELAGOA BAY RAILWAY. Near Waterval Boven Station the gradient is so steep that a cog-wheel attachment has been constructed to ensure greater safety. The road to the entrance of the tunnel is interesting: here the incline is tremendous, but the greatest care is taken and every precaution adopted against any eventuality. With a cog-wheel engine at one end and a powerful locomotive at the other there is little danger. The train rushes into a wonderful cutting of sheer granite 200 feet (61m) high. Six minutes are occupied in passing through the tunnel. On emerging into daylight on the other side a beautiful scene presents itself: great towering precipices, 600 to 800 feet in height (183 to 244m), with the Elands River sparkling and galloping over numerous boulders at the base of the hill, fringed with semi-tropical palms, thick bushes and ferns, the homes of tigers [sic] and baboons.
Ref: Anon, c. 1899. Picturesque South Africa - An album of Photographic Views. Cape Town: Dennis Edwards & Co. p 49.
Watch a video on YouTube on walking through the tunnel to the waterfall and back by Christiaan Kleynhans.
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