A Natural Wonder
The Zambezi River
The Victoria Falls
Formation of the Victoria Falls
People of the Victoria Falls
Enter the Ndebele
Discovery of the Victoria Falls
In Livingstone's Footsteps
Development of the Railway
To the Banks of the Zambezi
Development of the Falls
To The Congo
Development of Tourism
Development of Victoria Falls Town
Recent History
Further Information
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Discover the Victoria Falls with the Zambezi Book Company

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

Building the Victoria Falls Bridge

The first task after the completion of the railway allowed the transport of heavy machinery and materials to the Falls was the preperation of the foundations, the excavations for which had been previously prepared by contractors for 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.

Hobson (1907):

"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
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

Completing the Victoria Falls Bridge

The building of the bridge progressed smoothly and on 1 April 1905 the main arch was linked. In the previous twenty-four working days an average of twenty-one engineers erected some 500 tons of steelwork. At that time of year the spray of the Falls nearby is almost at its greatest intensity, and caused great discomfort to everyone employed on the works, particularly those on the south approach.

"The two centre panels of the arch were fixed about sunset on the 31st March, 4 months after the end posts had been erected, and it was found that the panels overlapped to the extent of about 1¼ inch. The steel truss had been exposed the whole of the day to the heat of the tropical sun and had elongated. When work was begun at sunrise next morning, it was found that it had contracted in the night to the extent of 1¼ inch." [Hobson, 1907]

During the night, the wind had changed and blown the spray of the Falls on to the bridge, cooling and contracting the metal.

The closing was a triumphant event and took place without a hitch. So precise were the calculations that Imbault had allowed for the fact of spray on the girders which would have slowed heat absorption and, therefore, expansion of the metal. There was great consternation just a few minutes after dawn that day when it was seen that, unpredictably, the wind had shifted and the bridge had remained dry. Fortunately, concern was unwarranted for the two great steel semi-arches were perfectly joined; the rivet holes of the cover plates and those of the boom coincided and were instantly bolted.


Finishing the lower arch of the bridge

Varian again describes the processes involved in more detail:

"Hand winches were rigged with steel ropes made fast around the two groups of twelve 1 1/4-inch steel cables which were holding up the whole... structure. In the event of any minor defect in the alignment in closing, a slight pressure from these on either side would swing and adjust the centre 250 feet away. During the erection, allowance had been made for adjusting the supporting steel cables in order to lower the structure into its final position.

"All were assembled at dawn. Connecting plates were in position, and on each side of the lower booms men stood by with drifts and service bolts ready to catch the rivet holes as they coincided and came into position. For some unaccountable reason on that morning and at that hour, the wind changed. The usual spray failed to fall on the bridge, with the consequence that the steelwork was dry and ready to absorb the heat, which might spoil the chance of a junction being effected that day. The sun rose, and started to warm one side of the steelwork, which immediately began to expand, while the gap closed perceptibly from the expansion, the warm side faster than the cooler one. There was an anxious few minutes as we wondered whether the action of the winches on the steel cables would be in time to sway the whole body of the steelwork into the direct alignment before the fast-closing gap could forestall it. Then, slowly, with the action of expansion closing, and the winches swinging the joint laterally, they coincided to make a perfect butt joint. As soon as the rivet holes of the cover plate, some four feet square, and those of the boom coincided, drifts were immediately driven and service bolts made the joint fast, very much to the relief of all concerned." [Varian, 1953]

The engineering company, Sir Douglas Fox and Partners, announced to the world that the great bridge over the gorge at the Victoria Falls, was linked up at 6 o'clock on Saturday morning, in the presence of Sir Charles Metcalfe, consulting engineer in Rhodesia, who had become known as "Uncle Charlie" to the engineers.

An engineering report from the time explained that there were anxious minutes as the sun rose and everyone watched to see whether the effects of its heat on the steel, and the tension of the structure at that critical moment when the hinged bearings took the strain had been accurately calculated.

The Daily Telegraph report was written up in the News of Barotseland:

"The British South Africa Company has received a cable from Sir Charles Metcalfe, their consulting engineer, now on the Zambesi, announcing that the bottom booms of the Victoria Falls Bridge were bolted at seven o’clock [British time] on Saturday morning, 1st April;... the two ends of the famous bridge over the Zambesi (each of which, from the necessities of the case, has had to be projected across the gorge) have now been safely joined. The slightest deviation from a just level would have caused great difficulties, and the satisfaction is the greater that this delicate feat of engineering has been accomplished."

The Bulawayo Chronicle reported:

"The junction this week of the two arms of the great steel arched bridge which spans the Zambesi gorge, over 400ft above water-level, is, says Engineering, evidence not only of British colonising enterprise, but of the skill and pluck of the British engineers, alike in design and construction. We have thus seen what was a generation ago an unexplored region subjected to the commercial and civilising influences of the railway engineer; and as the gorge spanned by the bridge was one – perhaps the greatest – obstacle to that great scheme of Cecil Rhodes for opening up Africa by a railway from the Cape to Cairo, the close of the steel-work is an event of far reaching importance."

On completion of the top boom, two hydraulic rams were inserted in the centre, exerting between them a permanent pressure of 500 tons. The joint was then riveted and the jacks removed. The upper boom was successfully connected in June, and a temporary track was immediately laid over the open steel work.

Hobson (1907) expands:

"Each half of the arch was designed to meet the other with a butt-joint in the arch-rib, and when in the course of erection the two half-arches met at this joint, their temporary character of cantilevers ceased, and the structure was transformed for the moment into a three-hinged arch, the top chord having a clearance or gap of several inches left in it. In this condition it is evident that the top chord and the spandrel-bracing only perform the duty of stiffening the arch, whilst they are themselves supported by it, and there is obviously no stress whatever in the central member of the top chord. In order, therefore, to secure the proper distribution of stress in all members due to the complete structure, it was necessary to impart the correct stress to this member artificially. With this object, hydraulic jacks were inserted in recesses prepared in the top chord adjacent to the gap, and the ends of the top chord were forced asunder until the required stress was imparted, regard being had to the temperature at the moment. Packings were afterwards specially made to fill the gap exactly. Joint-covers were then added, the rivet-holes at one end of each chord being drilled on the spot. A Table was prepared of the hydraulic pressures to be exerted in order to obtain the correct compression in the chord. " [Hobson, 1907]

Image showing the temporary rail-line and deck
Image showing the temporary rail-line and deck

By July all the steel work construction was complete, with only the riveting to be finished. The whole framework was originally connected with service bolts or pins, which were removed as the riveting proceeded. The riveting proved troublesome, taking a far longer period than was anticipated, owning to the difficulty in procuring men for this special class of work.

The temporary track was strengthened for light traffic, and alongside was laid a footway eight feet in width, made of loose timbers laid on the open steelwork, leaving the rest open to the gorge below.

Light traffic was then introduced, and was operated at night, starting in the evening as soon as the bridge-hands had knocked off for the day. The first train to cross, limited at that stage to two wagons and one light shunting locomotive, was the Jack Tar, which was then able to shunt materials between the southern construction yard and Pauling's Maramba Rail Depot on the northern side so that the rail line to Kalomo could progress whilst the bridge was completed. In fact some 50 miles had already been constructed with materials taken over the gorge by the Blondin.


Next page: The First Zambezi Regatta

Recommended Reading

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)

Further Reading

Roberts P (2020) Sun, Steel and Spray - A history of the Victoria Falls Bridge. Zambezi Book Company.

Sun, Steel and Spray - A history of the Victoria Falls Bridge


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Discover the Victoria Falls with the Zambezi Book Company

'To The Victoria Falls' aims to bring you the wonder of the Victoria Falls through a look at its natural and human history.

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