To The Victoria Falls
Development of the Victoria Falls
The following text is adapted from 'Sun, Steel & Spray - A History of the Victoria Falls Bridge', researched and written by Peter Roberts and first published in 2011. Please visit the Zambezi Book Company website for more information.
The Victoria Falls Bridge
Plans for a bridge crossing the Zambezi were quickly drawn up. The Victoria Falls Bridge was the brainchild of Cecil Rhodes, a key feature in his dream of a Cape to Cairo railway, even though he never visited the Victoria Falls and died two years before the railway reached them - before construction of the Bridge had begun.
Rhodes is often quoted to have said: "Build the bridge across the Zambezi where the trains, as they pass, will catch the spray of the Falls.". G A Hobson, engineer and designer of the bridge, in his account published in 1923 as part of Weinthal's great work 'The Story of the Cape to Cairo Railway and River Route from 1887–1922', explains:
"That he ever gave this direction has been doubted, and even denied by some people, including one, at least, of his own relatives; but I have it on the authority of one who, better than any other man living or dead should know the facts of the case, that the record is true." [Hobson, 1923]
The preliminary surveying of the ground for the bridge was made in 1900-01, during the time the Boer War was raging; communications southwards were cut, and the construction of the railway to Victoria Falls was much delayed, but never quite suspended, throughout military operations. The arena of the war did not include Rhodesia, and the work of railway construction never ceased throughout the whole period.
In 1900 Rhodes was asked to write a forward for the book 'From Cape to Cairo' by Grogan and Sharp. Ewart Scott Grogan, together with Harry Sharp undertook the epic overland journey from the Cape to Cairo, although Grogan was the only one to complete the entire journey, and thus become the first man to achieve such an undertaking. They travelled by train, boat and other means where they could, but walked for much of their journey across the African continent. Inspired by reading Frederic Courtney Selous's 'A Hunter's Wanderings in Africa', Grogan set out to prove his worth and gain the hand of his love in marriage. Their journey took three years, Grogan reaching Cairo in 1900.
Rhodes' introduction is an interesting statement of his vision:
"...every one supposes that the railway is being built with the only object that a human being may be able to get in at Cairo and get out at Cape Town.
"This is, of course, ridiculous. The object is to cut Africa through the centre, and the railway will pick up trade all along the route. The junctions to the East and West coasts, which will occur in the future, will be outlets for the traffic obtained along the route of the line as it passes through the centre of Africa. At any rate, up to Bulawayo, where I am now, it has been a payable undertaking, and I still think it will continue to be so as we advance into the far interior. We propose now to go on and cross the Zambesi just below the Victoria Falls. I should like to have the spray of the water over the carriages." [Grogan, 1900]
As Strage describes in his book 'Cape to Cairo', Rhodes' plan was ambitious:
"It was the concept that was bold, to the point of arrogance: to build a modern steel bridge supported by a single slender span here, in the middle of deserted jungle... Only fifty years earlier, David Livingstone had been the first European to describe them... and even now a simple visit to behold their grandeur required a carefully planned expedition. Even counting missionaries and curious officials, it is doubtful that more than a hundred or so white men had ever seen them. And this was not just a bridge, but the highest bridge in the world." [Strange, 1973]
Writing to the Daily Mail in March 1905, a few months before the bridge was officially opened, Sir Gilbert Parker observed:
"It was this gift of imagination which made Cecil Rhodes say, 'Build a bridge... where the trains as they pass will catch the spray from the falling Zambesi'. It was always so with him. He visualized and spiritualized his work, strange as this suggestion may seem to those who looked upon him as a materialist and a great adventurer. He was nearer the soul of things than the world knew."
Choosing the site of the Victoria Falls Bridge
Sir Charles Metcalfe, a close personal friend of Rhodes, followed his wishes and determined to locate the bridge just below the Falls. He carried out the preliminary examinations of the site in June 1901 before returning to Britain to raise funds for the project.
Metcalfe was to later write "no part of the railway was made for sentimental reasons", however the bridge is the one exception to his statement, and he played a large role in its location. As H F Varian, an engineer who joined the team building bridge and who would work with Pauling extending the railway line north observed:
"The choice of its site was more for sentiment than for practical reasons... A simpler crossing could have been achieved six miles further up, [near Kandahar Island] where the longest span need only have been 150 feet." [Varian, 1953]
The bridge designer, Hobson (1923) contended that below the Falls was the best possible site for the bridge.
"I am of the opinion that it is the best possible position for a bridge near to the Falls. The very beauty of the spot has, however, created objections to its selection. The situation is briefly this: The scene is laid within the tropical zone. At a place where the river is river a mile in width, the bright and lovely Zambezi, whose gentle rippling waters flow sparkling in the sun, is precipitated suddenly into a dark chasm which lies square across its path, and through only one constricted outlet down below the whole body of water forces its agitated way into a narrow deep and sinuous gorge beyond. The bridge crosses this gorge. " [Hobson, 1923]
He dismissed the alternative site, which was near the Old Drift settlement, saying:
" It would be a long straggling structure of no great beauty, and it would mar, to a large extent, the attractions of the broad, shining Zambezi, which presents at this spot a river scene of unparalleled beauty, scarcely inferior in its own way to that of the Falls." [Hobson, 1923]
But perhaps the most decisive factor was the cost, which would have been some three or four times that of the site across the gorge and require an extra eight miles of railway line.
Bridge location map (from Varian, 1953, Some African Milestones)
"The choice of the site was finally governed by the natural formation of the walls of the chasm, advantage being taken of the minimum distance to be spanned, combined with the soundest foothold obtainable. The position fixed upon is about 700 yards below the cataract.
"The profile of the chasm at this spot is very striking. The width at the top is approximately 650 feet, whilst the depth from the general level of the ground to the surface of the water below is about 400 feet. The left or north bank of the river is an almost perpendicular cliff, but the opposite bank has a shelf about half way up, and the whole region is composed of erupted rock, mostly basalt. The general level of the surrounding country is 3,000 feet above sea-level.
"The rock being very hard, the bridge was designed to fit the profile of the gorge with as little expenditure on excavation as possible ; and it would have done so, but for a mistake made by the surveyor in concluding that the rock on both sides was solid."
Designing the Victoria Falls Bridge
The main credit for designing the Victoria Falls Bridge must go to George Andrew Hobson of London based consultants Sir Douglas Fox and Partners (later to become Freeman, Fox and Partners), not as is often stated, Sir Ralph Freeman, the engineer who would later design of the famous Sydney Harbour Bridge in 1932 (and also the Birchenough Bridge across the Save River in 1935). At the time of the design of the Victoria Falls Bridge, Freeman was still only an assistant in the firm, although he was involved in calculating the preliminary stresses involved with the steelwork design and was credited by Hobson for his involvement. Hobson was made a Partner in the firm in 1901 and Ralph Freeman was to also become a partner and develop the outstanding reputation of the firm, expanding its horizons worldwide.
Hobson, in his final report on the construction of the bridge, to the British Institute of Civil Engineers in 1907, records that in 1901, while in London, Rhodes was shown a sketch of the bridge as it was then proposed to be built.
"Although he had never visited the locality, he was sufficiently familiar with it from travellers' descriptions and engineers' surveys to indicate in a general way the point of crossing. He determined that passengers in the trains going over the bridge should have a view of the Falls; and as the site on which the bridge now stands is practically the only one which could fulfil this purpose, it may be said to have been chosen by him. The preliminary design of the bridge above referred to was prepared to meet Mr. Rhodes's views, and it received his approval." [Hobson, 1907]
Among considerations that had to be borne in mind was, first, an appearance that would blend with the natural beauty of the site. Then followed the more material problems of rigidity (to permit railway traffic), economy in building to keep within the limits of the contract and, finally, a method of building that dispensed altogether with scaffolding.
The Bulawayo Chronicle Annual of 1901 contained an artist's impression of the bridge, as it was then proposed, and which provoked much disbelief.
"Several kinds [of design] were considered, but the nature of the situation and the purpose of the work made it obvious that a two-hinged spandrel-braced arch was the only one worth considering, as it completely and satisfactorily answered all the requirements of the case... A steel arch of this character was therefore designed to spring from the rock walls of the Zambezi chasm, to be erected cantilever-wise simultaneously from both sides. The best, though not the earliest, example of this type is the bridge which... now carries the Grand Trunk Railway over the Niagara Gorge." [Hobson, 1907]
A final consideration was the effect of the Falls themselves, and the spray from the waterfall on the steel structure:
"Care was exercised in designing the details to ensure simplicity in all sections, and the avoidance of enclosed parts or hidden spaces anywhere in the structure... There are no cavities for holding water, nor any surfaces where moisture can condense, the air being free to circulate everywhere. All the parts, in fact, are designed to be visible to the eye, and easily accessible to the painter's brush." [Hobson, 1923]
The bridge design selected is of the braced spandrel type; the horizontal top chord is linked by verticals to the lower chord or arc. The panels so formed are braced diagonally and thus the top chord, carrying the load, relieves the arc of some of the stress. The alternative, braced-rid design the load is borne wholly by the arc.
Hobson (1907) summarises the technical specifications of the bridge:
"The bridge consists of three spans. The end span on the left bank of the river is 62 feet 6 inches, and that on the other bank 87 feet 6 inches. These spans are composed of braced girders of ordinary type, 12 feet 6 inches deep, with horizontal upper and lower chords, and divided into square panels. The girders are fixed 20 feet apart. Connected with the end posts of the central span, they unite it with each bank of the river in a direct and simple manner. The deck is horizontal, and is laid on the top chords throughout the bridge... The cross girders, spaced 12 feet 6 inches apart, rest on the top chord.
"The central span is 500 feet from centre to centre of bearings, with a rise of 90 feet. The curvature of the arched rib is parabolic. The panels, twenty in number, are 25 feet in length. The depth of the girder at the crown is 15 feet, and at the abutment 105 feet. Each main girder stands in a plane at an inclination of 1 in 8 from the perpendicular. The width between the centres of the girders is 27 feet 6 inches at the top, and 53 feet 9 inches at the springing level, and the width between the parapets 30 feet. There is a camber of 9 inches in the top chord. " [Hobson, 1907]
A key element of the design are the pin-bearings introduced at the base of the main arch, with the four "feet" hinged to steel bearings mounted on concrete abutments. Under the hot African sun the steelwork of the great arch is designed to expand and lift slightly, turning on these hinged bearings, but at the same time retaining its rigidity without buckling or becoming distorted.
Hobson (1907) expands on the details of the hinged-bearing design:
"The entire bridge, with the exception of the main bearings, weighs approximately 1,500 tons. When the live load. (1,820 tons) is added to this a vertical load of 3,320 tons has to be supported by the foundations, of which only about 280 tons is borne by the outer ends of the shore spans, the greater portion being carried by the four bearings of the principal span. The total pressure due to the horizontal thrust of the arch and stresses due to temperature and wind-pressure is more than double this load. The calculated thrust which passes through each of the four hinged bearings amounts to 1,600 tons. On this account alone these bearings constitute a very important feature in the work ; and when it is considered that their duty is also to afford the steel frame of the bridge freedom to respond to wide variations of temperature without distorting itself or causing excessive strain, their importance can hardly be exaggerated.
"In designing the bearings the first part of the problem was to provide a means whereby the stresses which pass through the main rib, a hollow structure, whose sectional dimensions are about 3 feet square, could be collected and concentrated upon a straight line at right angles, not to the rib itself but to the resultant thrust of the arch, the straight line being the centre-line of the hinge bearing-pin on which each quarter of the bridge rests. In the next place the whole of the stresses have to be redistributed from this centre-line to the rock through a series of parts composed of bearing, pedestal, base-plate, and concrete monolith.
"An essential feature of the design is the uniform distribution of the load over the various parts which compose the bearing. The load must be placed uniformly upon the length of the pin, and in like manner the pin must be supported in its bearing, so as to avoid bending. The load having thus been transmitted to the pin, it must be equally distributed through the pedestal and thence to the baseplate which rests upon the concrete, so that the load on the latter may be uniform per square foot of bearing-surface. In order that the arch may fall and rise and the top chord may expand and contract with perfect freedom through a wide range of temperature, the hinges must be set square to the longitudinal axis of the bridge, not square to the arch-rib itself. The pin and its fellow in the opposite bearing must lie in the same straight line, like the hinges of a boxlid.
"The hinge-pin is 12 inches in diameter by 5 feet 10 inches in length ; it is made from a solid steel forging accurately turned all over, and a bolt-hole is drilled through the axis. Regarded in front elevation, the whole bearings, the pins especially, appear to be of very small dimensions, compared with the superstructure they carry. But they are of solid construction, and made of the strongest and toughest materials practicable." [Hobson, 1907]
Bridge design plan by G A Hobson
The main arch, a graceful parabolic curve, has a span of 500 feet. The truss of which it is composed is 15 feet deep at the centre and 105 feet at the springing. The rise of the arch is 90 feet.
The bridge is known as a trussed arch design. Each section was to be built outwards towards the centre from the sides of the gorge. As work progressed, these half spans were supported as cantilevers by steel wire cables running through galleries cut into the rock on either bank.
"The uninitiated, looking at pictures of the half-completed bridge, with its great arms projecting from the sides of the chasm, apparently supported by nothing at all, wonder how it is done. Owing to the immense depth of the chasm and of the water below, the idea of supporting the work during erection by means of scaffolding was not to be thought of, and happily it was not necessary... The design of the bridge when completed is that of a pure arch, self-supporting on its abutments; but throughout the process of its erecting, commencing from opposite sides, each half is a cantilever, and cantilevers they remain until, their end reaching out to each other, they join in mid-air.
"Now, a cantilever is simply another name for a bracket, and a bracket requires to be well fixed to the wall, or whatever it may be that holds it. The strength of the attachment must be equal to the weight exerted by the projecting portions of the bracket, with a sufficient surplus for safety. In the present case the means of attachment were provided by a series of steel wire ropes. These were secured at the top of each cantilever, and carried to a point some distance to the rear, where they entered holes bored in the solid rock, and their looped ends were buried therein. It was simply a matter of calculation how many ropes were necessary, what their united strength should be.
"The moment the two ends of the cantilevers met each other and were properly joined together… the function of the cantilevers ceased entirely." [Hobson, 1923]
At the time of construction it was the highest structure of its kind and had the widest span of any arch in the world.
Contracting the Work
The design was completed before tenders were invited by contractors. Hobson expands:
"Throughout the preparation of the design the question of erection was considered to be of primary importance, and every detail was devised to simplify the procedure. The arrangement to erect each half of the main girders as a cantilever was not only essential in the circumstances, but was by far the easiest plan, scaffolding being both impossible and unnecessary.
"In designing the details consideration had also to be given to the available means of transport by sea and rail, and particularly to the fact that the parts for one-half of the bridge would have to be conveyed across the great chasm by means of some temporary expedient.
"The contract was divided into two parts, namely, first, the construction of the steelwork in the makers' yard and the delivery of it on board ship in a British port; and secondly, the erection of the steelwork on the site. Tenders were invited from British, American, and German firms-the majority of whom ventured only to quote a price for the first part of the work. Only two firms, which were British, seemed determined to secure both parts of the contract.
"As was to be expected from the completeness of the design and the information laid before the parties tendering, the offers received for the first part of the contract were fairly close ; whilst as regards the two firms referred to there was hardly any difference between them. They, however, differed a good deal in their estimate of the cost of erection on the site, or it would be more correct to say, of their proposed plant for that purpose." [Hobson, 1907]
Several leading firms tendered for the construction of the bridge but most were daunted by the task and in the end, only two firms, Dorman, Long & Co. and the Cleveland Bridge & Engineering Company of Darlington, were in the running.
Hobson (1923) later expanded on the process:
" To go back to the time when one’s mind was almost wholly occupied in the work of design, and in the preparation of the specification and contract, there is a recollection of a haunting fear that some German or American firm would secure the contract... I may here observe that the fear of British firms shrinking from the task in the present case was well grounded, for one of the best known and highly reputed among them, after having expressed a desire to compete for the work, and having obtained all the needed information, turned craven at the last moment and failed to tender. This in spite of the fact that much thought had been given by the engineers to the idea of eliminating from the situation, as far as it was possible to do so, all the unknown, doubtful or incalculable factors associated with work of this nature. Although the site was in a remote part of the world, and there were many difficulties, the way was made easy for the contractor. For instance, all the preliminary clearing of the ground, and the excavation of the rock for the foundations, was done for him. He was provided with free transport to the spot of all the material for the bridge; houses were built for the workmen; and, in addition to all these efforts to save the contractor trouble and reduce his risk, a new and powerful apparatus was provided for the transport across the hitherto impassable gorge of one half of the material for the construction of the bridge, it being an essential feature of the engineers’ design that the structure be built out simultaneously from each bank. The apparatus referred to is, of course, the now famous cableway [known as ‘The Blondin’].
"Fortunately, all our British firms were not broken reeds; but it is a fact that only two of their number, by submitting a complete and reasonable offer, evinced any keen desire to participate in the undertaking. To the honour of The Cleveland Bridge and Engineering Company, of Darlington, personified by Mr Charles F Dixon, their managing director, who succeeded in getting the contract, and Messrs. Dorman Long and Company, of Middlesbrough, who were equally bent upon it and ran their rivals fairly close, that the saving of our British reputation for enterprise was due." [Hobson, 1923]
The railway contractors, Pauling & Co, also tendered for the contract. George Pauling was disappointed to loose the contract, but contented himself with the belief that the winning bid was too low, and that their was little profit to be gains. He wrote in his autobiography 'Chronicles of a Contractor':
"My firm had sent in a tender but it was too high; their tender, on the other hand, was too low, and I hardly think they made a profit on the work. I had had so great a connection with railway work in Rhodesia that I was sorry we had not the honour of building the bridge, but honour of that kind can be purchased at too heavy a price." [Pauling, 1926]
In May 1903 both parts of the contract were awarded to The Cleveland Bridge Company, to construct and erect the Victoria Falls Bridge for a price of £72,000. The company was also destined, thirty years later, to build another bridge across the Zambezi, the Lower Zambezi Bridge at Sena, Mozambique, with a total length of two and three quarter miles.
The cost of the work was identified approximately as (£) :-
Spare rope, conveyor and tires; 750
Excavations, exclusive of railway cutting, about; 6,550
"It was then anticipated that the construction of the railway up to the Falls would be completed by the end of that year or the beginning of the next, but unexpected difficulties were met with on the route, which caused a delay of 4 months. The rail-head actually reached the site at the end of May, 1904. Until then the transportation of the bridge-material was impossible." [Hobson, 1907]
The bridge was made, and assembled in sections to ensure accuracy, at the steel works in Darlington, England, and shipped in knocked down pieces to Beira on the S.S. Cromwell and then put on the Beira and Mashonaland Railway to Bulawayo, and on to the Victoria Falls on the new rail-line. With the view to hastening the arrival of the steelwork and its erection, the Railway company itself arranged for the transport of the materials. Mr Macrae was the forwarding contractor for the despatch of materials from Bulawayo.
"With few exceptions the bridge is constructed of rolled steel manufactured in England by the Siemens open-hearth acid process. All the plates and the principal angles were made by the Consett Iron Company, Durham. Material and workmanship were subjected to rigid inspection and proved to be of uniformly high character. The breaking stress of the tested pieces averaged 29.6 8 inches, and the limit of elasticity 60 per cent., all within a 2 per cent. margin of variation. The exceptions referred to consisted of steel forgings. No cast iron or cast steel was employed in the work. " [Hobson, 1907]
The location of the bridge, where it is frequently saturated by spray, demanded the inclusion of some rather interesting design features. To ensure that rust would never become established there is no portion of the bridge that cannot be examined by the human eye and no place that is not accessible to the painter's brush. There are no 'cups' or hollows that might hold water and all the important members of the structure can be entered by a man who can crawl through them.
"After a thorough cleansing and treatment with red-lead and linseed-oil (ascertained to be pure in quality), both before shipment and after erection, the steelwork was covered with three coats of Torbay paint of a specially selected silver-grey colour. This particular shade was chosen because a patch of rust in it will appear conspicuous by contrast. It has the further advantage of absorbing little of the heat of the sun. " [Hobson, 1907]
Hobson (1907) describes further:
"In order to check the accuracy and completeness of the work done in the bridge-yard, the erection on the contractor's premises of the whole of the work in sections was determined upon, and it may be here stated that this was so effectively performed that... when the steelwork was erected at the Victoria Falls, all the members met accurately together in their respective positions." [Hobson, 1907]
The Bridge Builders
Georges C Imbault, a young gifted French engineer working with The Cleveland Bridge Company, was appointed as their Chief Construction Engineer on site. He travelled out by steamliner to Cape Town and by rail to Bulawayo where he was joined by Sir Charles Metcalfe and Mr Stephen F Townsend, Resident Engineer for Rhodesia Railways, and together they travelled on to the Falls. At this time the construction of the railway was still more than one hundred miles short from its destination of the Falls, and they had a rough trek overland to complete their journey. On 2 September, 1903, Imbault viewed the site for the first time, assessing the scale of his task. It is recorded that Sir George Farrar, who was also there at the time, shot a fine buck within a few yards of the bridge site.
Colonel Frank Rhodes, Cecil's brother, apparently expressed strong displeasure when he heard that a Frenchman was to in charge of erecting the bridge, saying "Cecil would never have allowed anyone but a British engineer"! Imbault had been selected because of his experience with cables and overhead electric conveyors, an essential element in the construction of the bridge, and his selection was amply justified.
Mr S F Townsend was originally on the staff of the Cape Government Railways, and had been responsible for the construction of the Orange River Bridge, then the longest bridge in Africa. He was appointed to the Rhodesia Railways by Cecil Rhodes, on the start of the great scheme from Vryburg, and continued with the company as Chief Resident Engineer, based in Bulawayo, until after the main line reached the Congo Border in 1909.
Mr William Tower was chief assistant engineer to Townsend, and had been in charge of most of the surveying north from Vryburg. He was head of construction between Bulawayo and Salisbury, and for part of the line from Bulawayo to the Victoria Falls, where he was Resident Engineer for the construction of the bridge. His assistants at the start of the works were Mr C Everard and Mr Beresford Fox.
A construction yard was established on the south bank, where all bridge materials were stored. A temporary camp for the bridge construction engineers was set in early 1904 about a kilometre from the construction yard, on the south side of the old track leading to Clark's Ferry, and named Tower's Camp. Beresford Fox oversaw construction of the camp and put up fifteen to twenty huts for the benefit of the railway and bridge construction workers. Another camp was later established on the left bank, known varyingly as Imbault's or Salmon's (one of the railway surveyors) camp.
Victoria Falls Bridge Construction Camp; Tower's Camp on the south bank
The Railway company also oversaw the excavation of the rock in preparation for the bridge foundations, and which was contracted to a Bulawayo based company. A small group of five Europeans, assisted by a team of Africans, cleared the rubble from the slopes of the gorge and exposed the hard rock foundations in preparation for the mass of steel it was to carry.
Connecting the Gorge
At that time the nearest possible point of transit was cross the river above the Falls at Giese's Drift, just above the Devil's Cataract on the south side of the river. From this point a canoe was needed to cross to Maramba Drift on the northern bank, and then back down to the bridge site, a distance of three miles or more, taking several hours, and not without its dangers - wild animals roamed the area, as they still do today.
One of the first tasks was to establish a cable system across the gorge. This was achieved in October 1903 by firing a rocket across the gorge carrying with it a string. When this was secured on the other side, a stronger cord was taken across and finally a telephone wire, next a marked wire was passed across and a string put on it by means of a spring balance to compute the side or sag of the wire. Before the rocket was fired, attempts had been made to fly a string across by means of a kite, but this ingenious effort was foiled by the eddies and currents of air from the tumultuous waters which tossed the kite in every direction but the right one. Another problem was mist from the Falls which hampered the accurate surveying required.
At the third trial the rocket dropped in a position which enabled the line to be secured. By means of the line a rope was drawn across, and by means of the rope, followed finally by a 3/8th inch stranded rope of steel. This was passed over a 12-inch pulley fixed in a stout log which in turn was firmly bedded in the rock on the very edge of the cliff. The tactics were then reversed, and when the free end of the pulley rope was dragged back to the south bank, it was pulled tight and taken twice round the barrel of a windlass and securely spliced to its other end. The position of this was downstream, a few yards from the bridge site, and this small cable system successfully transported small loads, tools and even people throughout the building of the bridge. A telephone line was also established across the gorge for effective communication.
After overseeing these initial preparations, Imbault returned to England in October 1903.
The Bosun's Chair
Passengers were taken over one at a time on a bosun's chair suspended from small pulleys running on the cable which was worked by a hand winch. For safety there was attached a canvas bag which could be strapped round the legs and across the chest. H F Varian, one of Pauling's engineers who worked on the bridge, wrote:
"A wooden box, five feet cubed, was slung on two steel sheaves from the steel rope, and drawn by a light steel wire... It was a primitive mode of transport. The supporting wire sagged ominously in the middle of the gorge, and if one disliked heights, there was plenty of time to brood in transit as the flimsy box jerked its way across. " [Varian, 1953]
Mr Beresford Fox was responsible for setting up the cable system, and got the short-straw to make the first passage across the chasm. In a letter to his father Sir Francis Fox in 1903 he wrote:
"We could not obtain a trolley in Bulawayo and so, temporarily, we have to do the best we can: the present arrangement is safe, but not good mechanically. As they tied me into the bosun's chair I must admit to feeling a bit strange in relying absolutely on my own calculations for my safety. The chair is a piece of wood suspended by four ropes, with a canvas back and a sack and board as a foot-rest. Of course one is so tied in that were you to lose consciousness you could not fall out; this precaution, for some people is advisable." [Hyder Consulting, 2007]
By means of this simple system, engineers and workmen were to cross the chasm daily, and foodstuffs and material were transported to the northern side.
Charles Beresford Fox crossing the gorge for the first time in the 'Bosun's chair', November 1903.
In March 1904 Imbault travelled back to the site with the first contingent of British workmen, mainly English engineers. Among the group was A T Prince, assistant engineer, who would later publish one of the first accounts of the work. Writing in the American publication The World's Work in 1906 he records:
"We travelled from Cape Town to Bulawayo in the train de luxe, which is wonderfully comfortable and rather upsets the ideas of those who come to Africa expecting to have to rough it. There are many trains in Europe which would suffer badly in comparison.
"From the rail-head, however, we had to finish our journey part of the way sitting in the trucks of a construction train and part by post cart. The post cart trip of about thirty-five miles [56km] occupied two days instead of ten hours, as we had expected and provided for. On the second night, from a distance of five miles, as we approached, we had a superb view of the spray from the fall lighted up by a full moon. This spray column, we afterwards found by measurement, rises more than two thousand feet into the air on a calm day with the river in flood.
"On the following morning we saw the falls themselves, and those who have not been fortunate enough to see them can form small idea of their grandeur. " [Prince, 1906]
With the railhead approaching the Victoria Falls, heavy construction materials could at last be transported to the site. Imbault's next task was the installation of a more powerful cable system to transport the large volume of building materials needed to the north bank.
"In July, 1903, tenders had been invited for a cableway to span a distance of 870 feet [265.18 metres] and carry a load of 10 tons net. The conveyor was specified to be capable of lifting and lowering as well as travelling with this load, and to be operated by means of electricity."
"In effect the principle of the apparatus is that of an overhead travelling crane in a workshop, but instead of running on a solid rail it runs on a wire rope; the driver sits in the travelling carriage, and from there he controls the lifting, lowering, and travelling movements."
"The design at the time was comparatively new, and no apparatus of the kind had hitherto been made on such a large scale. It was therefore regarded-in some quarters-with ill-concealed suspicion." [Hobson, 1907]
Situated on the upstream side of the bridge, the apparatus was installed and in working order by the 28th July 1904. Before the transporter could be used for the first time it was necessary to clear the cable of various pulleys that had been used in positioning it and which had all gravitated to the lowest position, over the centre of the gorge. The Chief Engineer, Imbault, had to undertake the dangerous work himself, as one of the engineers recalled:
"Despite the offer of a bonus, not one of the workers would undertake the job and finally the chief engineer had to do it himself... it was an eerie sensation watching this man standing on a narrow plank in front of the gently swaying machine, 450 feet [137 metres] in the air, using both hands to undo the steel lashings, and passing the pulleys one by one to the driver at the back. A moment of vertigo, a false balance, and certain death. Truly he was nerveless." [Powell, 1930]
The electronic transporter system became known as ‘the Blondin’ after the daredevil tightrope walker Charles Blondin who had famously crossed the Niagara Falls by rope in 1859. Electricity came from a portable steam-driven engine and dynamo which was located near the construction yard on the south bank. In addition to transporting half of the steelwork for the bridge across the gorge, over 40 miles of track materials were also transported using the Blondin. This allowed the railway construction gangs to continue the development of the line north before the bridge itself was completed.
The 'Jack Tar'
It was desirable that an light shunting engine be based on the north side of the Zambezi whilst the bridge was being completed, and so the 19 ton 'Jack Tar' locomotive was dismantled and transported over the gorge piece by piece by means of the Blondin cableway. The boiler and lighter parts sent over first. What was left, the body frame and cylinders, weighed twelve tons and had to be transported in one piece. Varian describes how the cable sagged under this load and dangled over the gorge with a fourteen metre drop in the cable. There it hung for three hours as the Blondin's engine struggled to cope with its weight, until boosting of the power in the electrical plant and by other means the carrier slowly managed to pull itself to the other side. The driver sitting in his little seat with a drop of 350 feet below him is said to have coolly smoked throughout his ordeal.
The Jack Tar
Built in 1889 by Manning Wardle & Co of Leeds, Yorkshire, the Jack Tar engine was purchased by Pauling & Co, the railway construction contractors, in 1896. It was shipped to Beira and assembled at Umtali, where it was used on the widening of the Beira railway, before being transferred to Victoria Falls in 1904-1905.
The Jack Tar pulled the first train in Northern Rhodesia, over a short two mile track built in a day by the railway construction workers.
The Jack Tar made further history by being the first locomotive engine to cross the completed bridge, although the official first train service was only on the official opening several months later.
When working trucks over one night soon after the opening of the temporary rail-line over the bridge, its side rods killed a leopard crouching on the walkway beside the track. Perhaps injured or ill, or without space to run, the animal refused to flee from the advancing train and its skull was crushed.
After the bridge was finished the Jack Tar returned to Beira for light shunting duties. In 1927 it was transferred to Bulawayo. In 1935 re-boilering was necessary and other changes made in appearance, including the provision of a brass dome and cap to the chimney, while a new fully enclosed cab was fitted in place of the original open shelter. The black livery was replaced with dark green, lined with yellow. One loss was the little anchor fitted to the front of the chimney.
By 1942 the locomotive was moved to Umtali, before finally being withdrawn from service. Exhibited at the Rhodes Centenary Exhibition at Bulawayo in 1953, it was later loaned to the Umtali Museum. The engine is now fully restored and part of the Bulawayo Railway Museum collection.
Building the Victoria Falls Bridge
The first work after the completion of the railway up to the site was, of course, the building of the concrete foundations, the excavations for which had been previously prepared by the permanent staff of the railway-company.
"In setting out the bridge the span had been measured in the first place by triangulation, and finally by direct measurement with wire. A wire was set up along a measured length of 500 feet on level ground on the bank, secured at one end and subjected to a known tension at the other; it was then marked to correspond with the measured length of 500 feet.
The wire was then used to measure the span direct, being subjected to the same tension. So long as this tension remained constant the straight length between the marks was 500 feet and was independent of the deflection, whether such deflection was due to the weight of the wire or to wind-pressure upon it. To ensure accuracy the measurement was repeated with different wires. " [Hobson, 1907]
The start of the project had been significantly delayed because the south side provided no solid foundation rock until a depth of about 15 metres was reached. A error had been made by the surveyors in the assessment of the foundations, on account of which the bridge had to be lowered from the position intended.
Hobson (1907) records:
"The mistake was perhaps excusable, and was not discovered until the vegetation which thrives in the hot sun and the spray from the falls had been removed, and the work of clearing the ground and the excavation of the rock had proceeded for some time. It was then found that the shelf on the right bank on which it was intended to rest one end of the principal span was covered to a considerable depth with debris. By the time the error had been discovered, the preparation of the steelwork was too far advanced to permit of any alteration being made in the structure. The difficulty had therefore to be overcome partly by increasing the depth of the concrete foundations, and partly by lowering the level of the entire bridge to the extent of 21 feet; but both time and money would have been saved had the true facts of the case been recognized at the beginning, the span designed 25 feet longer, and the truss increased in depth at the ends by 20 feet." [Hobson, 1907]
Owing to the lowering of the bridge, the line had to run in a cutting on each side of the gorge, and not, as had been planned, at the same level of the Falls.
" The size of the excavation on the left bank was small, the rock there being sound, but its position on the face of an almost perpendicular cliff rendered work slow and dangerous. On the right bank it was more easily accessible, but was considerably larger owing to the burden of debris which had to be removed.
"The lower part of the concrete was reinforced with old rails, and the upper part with 2-inch steel rods with their ends bent for greater security. The top, for the reception of the base-plate, was strengthened with steel joists 6 inches by 45 inches by 20 lbs., laid transversely to the joists in the base-plate. Four bolts 3 inches in diameter were inserted in each concrete block for holding down the base-plate. In order to allow for a slight adjustment after the concrete had set, the bolts were fitted into tubes 43 inches in diameter, the intervening space, after final adjustment had taken place, being filled with cement grout under pressure. Six weeks were allowed to lapse after completion, before any great weight was placed upon it in order to ensure the setting and hardening of the concrete. " [Hobson, 1907]
The greatest possible care was taken to make the pedestal and base-plate true, as it was recognized that one setting here would give the direction and correct distance for the bearing-pin, and therefore of the whole structure. It was carefully adjusted by means of wedges, and when absolute accuracy of position and elevation had been attained, cement grout was forced, under pressure, through a series of pipes specially located for the purpose, over the whole bearing area.
One of the four main bearings, or 'feet', of the bridge
The specification for this concrete work was rigidly enforced. For convenience, all concrete was mixed on the foundation site on the south bank, and transported to the north bank in batches. Any batch not placed in position within 20 minutes after mixing was discarded into the gorge.
Varian describes the work:
"All materials for the foundations had to be lowered from the Blondin at both ends. A steel bucket, four feet in diameter and four feet deep, carried all materials such as sand, cement and water. Visiting that part of the work was another unpleasant little trip. By the time the bucket was lowered to the requisite depth, on some 150 feet of single rope, it had an unsettling trick of revolving violently one way, then stopping, and revolving with equal violence in the opposite direction." [Varian, 1953]
Work having started in May, the concrete foundations for the bridge were finally ready in October 1904. At the same time the anchorages for sustaining the main span during its cantilever stage were prepared, with the erection of the end posts, which commenced on 21 October. The two side spans of the bridge, supported on the abutments and anchored to the rock behind by steel cables, were completed in late December 1904.
Erection of the side spans proved to be one of the biggest challenges in construction. Hobson records:
"The really difficult and risky part of the work of erection lay in the end spans, which now look so small as compared with the arch itself that they are scarcely noticed. But once the tall end posts of the main arch were erected, and the short spans were connected with them and the shore, thus affording a stable platform to start from, the rest was easy and rapid work. This stage was actually reached during the last days of 1904." [Hobson, 1923]
Hobson (1907) continues:
"The work of erecting the steelwork actually began in August, 1904, and the most difficult and slowest part of it proved to be the operations of fixing the shore spans and connecting them with the end posts of the main girders. The ends of the shore spans were let into recesses cut out of the rock and anchored by their upper corners. They were built out a certain distance as cantilevers, and at a further stage supported by scaffolding fixed on the slope of the cliff. As soon as the end post of the main span was up, the shore span connected with it and the anchorage coupled, a stable platform was obtained and the rest was easy and expeditious work. " [Hobson, 1907]
Early construction of the Victoria Falls Bridge
"The shore ends of the short spans rest upon roller-bearings which allow to the whole structure perfect freedom of movement in a longitudinal direction under variations of temperature.
"At the intersection of the end post with the top boom, and the first diagonal tie, a large steel pin is inserted through all the plates which compose these members. The pin is 7 inches in diameter and 7 feet long, its outer ends being held by means of short links attached to the top booms. To this pin were attached the anchorage-cables during the erection of the bridge." [Hobson, 1907]
Once underway the building of the main arch progressed rapidly. The arch was erected simultaneously from either side as two cantilevers, with the two arms anchored on either side by twelve high tension steel wire hawsers running through galleries cut into the rock.
Hobson (1907) expands:
"The contractors' engineer... devised a system in which comparatively small wire-ropes, easily carried and handled, played the most prominent part. A high quality of steel was used, and each rope was 1 13/32 inch in diameter, spirally laid, 91 ply, and had a breaking stress of 130 tons. Each end of every rope was fitted with an ordinary screw-adjustment, proportionate to its size and strength. The total load to be borne being known, it was only a question of how many ropes would be required and how much of the solid rock in the adjoining ground behind the bridge it was necessary to lay hold of." [Hobson, 1907]
Varian describes the cable system in more detail:
"The system of suspension of the steelwork as it extended from each side until the lower boom was joined, was achieved by means of twelve 1 ¼-inch steel hawsers. These were made fast to a steel pin six inches in diameter at the top of each side of the impost, and adjusted with union screws. From the pins they were led back level until clear of the bridge, then down a vertical shaft through the live rock, tunnelled across, and led up another shaft on the other side to form a similar connection on the other side of the impost. The thrust of the arch on the lower end of the imposts was taken up on a twelve-inch steel hinged bearing, which in turn was set in a block of strongly reinforced concrete. This type of construction was also used by Sir Ralph Freeman, only in a far more elaborate manner, in the design of the Sydney Bridge." [Varian, 1953]
Travelling along the cross girders were two of Imbault's specially designed and very successful electric cranes, with two arms, each commanding a radius of 30 feet and able to revolve in an arc of nearly 180', and which handled the lifting and lowering of the steel sections into position. Capable of carrying 10 tons, these were arranged to stand on the cross girders and moved forward as each panel or 'bay' of twenty-five feet was completed. This stage was reached on the right bank early in December, 1904, and on the left bank during the last days of the same month.
"The first panels, being the largest and containing the most material, naturally occupied the longest time, 2 to 3 weeks ; but this was gradually reduced until at the centre, eight posts and their fellow members were placed in position in 26 days, the work, of course, being done simultaneously from both sides of the river, so that each panel occupied 6 days in erection ; and this rapidity was attained in spite of delay caused by the delivery of the material failing to keep pace with the progress of the erection, which constitutes fair testimony not only to the efficiency of the design, but also to the precision achieved in the workmanship" [Hobson, 1907]
Hobson (1907) describes the attention to detail required in completing each panel section of the bridge.
"The butt-joints of the main arch-rib were planed to the exact angle calculated for each joint. This angle differs in every instance in the half span, owing to the curve being parabolic and not segmental. Every effort was made to attain accuracy and soundness of construction, and to this end the lengths of the members between the joints of the 25-foot panels were specified to vary not more than 1/32 in. from the calculated length. With few exceptions, all rivets were accessible for mechanical closing, the absence of box-sections making this easy to accomplish." [Hobson, 1907]
Hobson (1907) also highlights an innovative technique used during the erection of the bridge:
"To facilitate erection and secure accuracy in alignment, a turned steel pin was inserted at the point of intersection of each vertical and diagonal member with the top chord and arched rib... The point was temporarily fitted with a cone to facilitate its being threaded through the holes in the plates. This system proved advantageous in every respect. Time in erection was saved and, once the pin was in its place, confidence in the accuracy of the work so far done was at once established. Reinforcement of the pin by rivets or service bolts was a matter that could be attended to when all the members constituting one panel were in place, and it was not necessary to wait for the insertion of all the rivets in one particular panel before proceeding with the work of erecting the next." [Hobson, 1907]
Hobson credits the Cleveland Bridge Company, and specifically their engineer, Imbault, for rising to the challenge of erecting the structure:
"The Cleveland Company... deserve credit for their skill in devising a simple, economical apparatus for the erection of the bridge. This is due to the ingenuity of their engineer, Mr G C Imbault, whose special knowledge, amongst his other qualifications, of the use and manipulation of wire ropes stood him in good stead in the present instance, and at the same time raised the reputation of this firm to the front rank." [Hobson, 1923]
Constructing the Victoria Falls Bridge, image showing the safety net
As the work was proceeding from the two sides of the gorge, daily observations were taken to see that the centre line of the bridge was maintained.
A team of about 30 skilled European engineers erected the steelwork, assisted by hundreds of local African labourers, being paid from 10 shillings to £3 per month. As many as 400 had been employed at one period, although the average number during construction was about 200.
"Although it had been the aim of the engineers to do it in the dry months of the year 1904, and thus avoid the climatic period fraught with risk to the health of fresh-blooded Europeans, it is interesting to note that, owing to various delays, the work was done in the following rainy season and that no serious harm ensued. The rains begin in October and end in May. The worst rainy months are March and April. In addition to rain the bridge is wetted by the spray from the falls, which is, of course, influenced by the height of the columns of spray, which in the rainy season rise to 3,000 feet, and also by the direction of the wind. The spray is heaviest in the months of March, April, and May." [Hobson, 1907]
A net provided for the safety of the men had been slung on wire ropes stretched tight across the gorge and as close up to the arch as possible, about three hundred feet above the water. It is reported that the first viewing of this heady sight sent the African workforce on strike as they thought they would be expected to leap into the net.
In an engineering report, Hobson describes how the net had been moved pari passu, and so the distance from the underside of the arch had increased until the centre was reached. Photographs from the construction of the bridge however only show the safety net in one, central, position.
Fortunately the net was never been called into use other than to catch tools, of which there was a small collection when finished (as can be seen in some of the photographs), and the workmen even complained that it actually made them more feel nervous.
The nearly finished bridge
Fox, Francis, Sir. (1924) Sixty-three years of engineering, scientific and social work. London, J. Murray
Hobson, G A (1905) The Victoria Falls Bridge, The African World, Vol 3, 9 December, p107
Hobson, G (1907) The Victoria Falls Bridge. Institution of Civil Engineers, Session 1906-1907, Part IV, Section 1. Minutes of Proceedings 19 March, 1907 (Paper No 3675). Volume 170,January 1907, Pages 1–49.
Hobson, G (1923) The Great Zambesi Bridge - The Story of a Famous Engineering Feat. In Weinthal, L
Hyder Consulting (2007) Footprints on a Global Landscape – 100 years of improving the built environment. Hyder Consulting.
Pauling, G. (1926) Chronicles of a Contractor
Roberts P (2016) Sun, Steel and Spray - A history of the Victoria Falls Bridge. Zambezi Book Company.
Varian, H F (1953) Some African Milestones Wheatley : George Ronald. (Reprinted 1973 Books of Rhodesia).
Weinthal, L (1923) The Story of the Cape to Cairo Railway and River Route from 1887–1922 (Pioneer Publishing Co)
'To The Victoria Falls' aims to bring you the wonder of the Victoria Falls through a look at its natural and human history.
This website has been developed using information researched from a wide variety of sources, including books, magazines and websites etc too numerous to mention or credit individually, although many key references are identified on our References page. Many of the images contained in this website have been sourced from old photographic postcards and publications and no infringement of copyright is intended. We warmly welcome any donations of photographs or information to this website.
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