NZASM tunnel at Waterval Boven

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).

When Paul Kruger’s announcement to the Volksraad that a route had been found through the Elands River Valley met with disbelief, this inhospitable and uninhabited terrain being considered impassable, he thundered that ’If I tell you that the Dutch have found a route through the valley, who are you to doubt them!”

The tunnel formed part of the rack-railway system between Waterval Onder and Waterval Boven, in itself unique, being, in its time, only the second of its sort outside of Switzerland. It was surveyed by the engineers Sissingh and chief foreman Bouten. The construction was contracted to the firm of Warren & Royce. Drilling and rock-blasting began from both ends on 18 October 1892, 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, considering that the tunnel was also constructed to a 250m radius.

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. At approximately the halfway mark an arched niche was constructed on one side for the 'ploegbazen' (gangers) and workmen working in the tunnel to escape to, thereby avoiding the oncoming trains. However, should they not have time enough to reach it their instruction was that “they will lie down between the line and the wall”!

Architects:
NZASM: Nederlandsche Zuid-Afrikaansche Spoorweg-Maatschappij

Sources:
Artefacts (accessed 28 April 2016).