(Contributed by the Chief Engineer)
Recent visitors to the Falls will no doubt have noticed that steel footways have been added to the bridge. The work is now finished, and a brief description will probably be of interest.
For many years it was felt that facilities for inspection and painting of the Falls bridge were inadequate, especially after the new deck with its roadway, railway track and footpath was added in 1929.
The question of providing access to the bridge for the purpose of maintenance was not simple. Many of the suggestions considered before the final scheme was evolved were technically good, but they could not be adopted as they spoilt the lines and appearance of the bridge
The present scheme combines the purpose of utility and good appearance.
On each side of the bridge there are two gangways running from shore to shore, with a system of intercommunicating ladders. Top gangways are placed against the top booms of the bridge, under the deck, where the heavy shadows from the roadway and footway make them inconspicuous and in fact invisible from any great distance.
The handrails of these top gangways are capably of carrying travelling cradles for use in inspecting and painting the outer faces of the main arch girders.
The lower gangways follow the curve of the arch and here the handrails have been designed to be used also as compressed air mains. It is necessary only to couple a compressor to either handrail for compressed air to be available at any part of the bridge to operate pneumatic tools for any necessary work.
Cradles have also been arranged to work from the outer hand rails of the roadway and public footway, while steel ladders give access to main bearings and other important points.
In any scheme it was necessary to keep the weight down to a minimum, as the gangways do not add any strength to the bridge. Few people looking at the light construction of the gangways, with their open mesh floors, will realise that over sixty tons of materials have been used in the whole scheme of ladders, gangways and cradles.
Owing to the heavy spray from the Victoria Falls the steelwork of the bridge is almost constantly wet for nearly six months in each year, and painting can be done only during the remaining six months when the steel work is comparatively dry. This involves the application of over 1,200 gallons of paint. On many of the large bridges in other countries it is possible to keep a small gang almost constantly employed, and the work of painting and maintenance is thus rendered easier.
By means of the gangways and cradles described above the greater part of the bridge is brought within easy reach for inspection, painting or scaffolding for any work. For those parts of the bridge that are not directly accessible, safety belts are provided to facilitate rapid and efficient attention.
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