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Remnants of two old Stone and Iron Bridges over the Hex River near the Olifantsnekdam, Magaliesberg

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Author:Voges, Konrad
In:Artefacts
Date:2014
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The bridges were built in 1904/05 during the Reconstruction period after the Anglo-Boer War.


Area Map

One of the bridges was built at Kroondal on the Pretoria - Rustenburg road [R104] (25°42'53"S - 27°18'57"E).
Fig 2 Present-day new and old bridges at Kroondal

The other lies at Olifantshoek on the Krugersdorp - Rustenburg road [R24] (25°51'32"S - 27°17'31"E).
Fig 3 Left bank abutment at Olifantshoek hidden by trees

The contract for the erection of the foundations of both bridges was awarded to Karl Heyne, master builder of Rustenburg. He was fortunate in acquiring the services of a team of Italian stone masons for the work involved.

The foundations were laid on rock bed and were built up entirely in stonework - grey granite which was quarried by three Kroondal farmers – namely the brothers Adolf and Georg Wenhold and their brother-in-law Johannes Penzhorn. The quarry was situated at Pampoenkop (25°40'50”S - 27°21'53”E), a hillock some 10km north-eastwards from the construction site at Kroondal. The rocks were cut to size, squared and dressed by the stonemasons on the construction site.
Fig 4 Quarry at Pampoenkop identified

The bridge at Kroondal has a 5m wide single carriageway structure with two spans of 25m length each. The stonework for the two abutments and the single pier is made up in squared rubble masonry and laid in random courses. The pier is cut-water shaped, both up- and downstream. The approaches to the bridge are safeguarded by parapet walls topped with coping stones. Token parapets finish off the top of the pier.
Fig 5 Pier - cut-water shaped

The steel structure came from England in pre-fabricated form. The Warren Truss girders were assembled in England. Each truss was divided up into four sections; these were jointed on site by means of riveted fish plates.
Fig 6 Steel girders jointed - fish plates & rivets

This bridge is in a fair condition although one span is in danger of collapse. Loads of rubble have been dumped onto the bridge – presumably to stop people from driving across; and scavengers are removing struts from the trusses, thus weakening the structure. Fig 7 Bridge sagging
Fig 8 Strut removed

The bridge at Olifantshoek also is a single carriage-way structure of 5m width with a span of 30m length. However the steel structure has been removed, presumably when the new bridge came into use. One 4m length of a girder was left behind and lies half-submerged in the river bed.
Fig 9 Girder remnant

Whether the material for the abutments here also came from the Pampoenkop quarry is not certain but quite probable since colour and grain of the granite are similar.

The foremost task of abutments is to bear the weight of the steel structure of the bridge. At the same time their U-shaped form serves as retaining walls for the earthen fill of the bridge approach.
Fig 10 Steel structure resting on foundation

The abutment on the right-hand bank is in perfect condition; the opposite one evidently suffered some damage during the demolition, thus exposing the road-bed structure. There one can observe how the fill was made up from the waste and debris accumulated during the masons' dressing of the stones.
Fig 11 Left bank abutment in full view
Fig 12 Road bed
Fig 13 Joists & troughs carrying road bed

One can reasonably assume that the two bridges were built one after the other. The lay-out and appearance of the abutments are the same. Yet there are some slight differences in the execution of the work. The stonework of the Kroondal bridge looks more rustic. The bonding of the random courses at Olifantshoek is done more effectively. The parapet walls of the latter look neater.
Fig 14 Stonework random coursed
Fig 15 Parapet atop the foundation, perfect bonding

This suggests one of two things, that the work on the two bridges went on simultaneously after all, that there had been two different teams of masons at work. Or that the masons who had done first the work at Kroondal, were able to improve on their performance when they built the second set of foundations. Karl Heyne, having a reputation for excellence of workmanship, possibly coerced them into doing so.

Both bridges were replaced by dual carriage-way ones in the early 1960ies.


Fig 2 Present-day new and old bridges at Kroondal


Fig 3 Left bank abutment at Olifantshoek hidden by trees


Fig 4 Quarry at Pampoenkop identified


Fig 5 Pier - cut-water shaped


Fig 6 Steel girders jointed - fish plates & rivets


Fig 7 Bridge sagging


Fig 8 Strut removed


Fig 9 Girder remnant


Fig 10 Steel structure resting on foundation


Fig 11 Left bank abutment in full view


Fig 12 Road bed


Fig 13 Joists & troughs carrying road bed


Fig 14 Stonework random coursed


Fig 15 Parapet atop the foundation, perfect bonding