Cannon Street Railway Bridge

2023

2023

Cannon Street Railway Bridge crosses the Thames in central London. Downstream, the next bridge is London Bridge, and upstream Southwark Bridge. It carries trains over the river to Cannon Street Railway Station on the north bank. It was originally named Alexandra Bridge after Alexandra of Denmark who was the wife of the future King Edward VII.

The bridge was designed by John Hawkshaw and John Wolfe Barry for the South Eastern Railway.

It was opened in 1866 after three years of construction. In its original form, it carried the railway over the Thames on five spans standing on cast-iron Doric pillars. It was subsequently widened between 1886–93 by Francis Brady and extensively renovated between 1979–82, which resulted in many of its ornamental features being removed and the structure taking on an even more utilitarian appearance than before.

As built and rebuilt in Victorian times, the impressive decorative ironwork provided visual interest, but all that remains visible are portions of the fluted columns. The upper parts of the columns were encased in concrete as part of the strengthening works undertaken in the early 1980s. The latter-day alterations offered little scope for providing visual appeal, and the authorities evidently admitted defeat, judging by the plethora of corrugated sheet cladding.

It was the scene of the Marchioness disaster in 1989.

Press Reports and Technical Information

1865 'The City Extension of the Charing-cross Railway to Cannon-street is being pushed forward with considerable energy on the part of the contractors. This extension is designed to fulfil two distinct uses: the first to convey passengers coming from the south-eastern district into the heart of the City, and the other to form a means oommunication between Charing-cross—the centre, as it were, of the west-end district — and Cannon-street — the most central point of the City with regard to the great thoroughfares of business. ....
... These works comprise the widest railway bridge yet built over the Thames, indeed in any part of the world, a terminus which will be considerably larger than that of Charing-cross station, and an iron viaduct over the Borough Market supported on cast iron pillars. The remainder of the railway, with the exception of an iron bridge over Park-street, is built on a brick viaduct of the ordinary description.

'The bridge is, of course, the great work, and in its construction, Mr. Hawkshaw, the engineer, has employed, on a larger scale, the same principle which answered so successfully at the bridge at Charing-cross.
Cast-iron cylinders, 18 feet in diameter, and, in the first instance, about 13 feet high, are bolted together in segments. In this stage of the proceedings they resemble in shape enormous drums with the top and bottom open, and when made water-tight all round their circumference they are dropped carefully into the bed of the river. The upper surface of the bed consists of mud or silt, through which the water passes freely, but at a short distance downwards the London clay is reached, which is completely impervious to water. The object of the engineer is to reach this water-tight stratum. After the cylinder has been placed in its proper position on the bed of the river, the mud or silt inside it is excavated either by divers working in helmets, or more generallv by the process technically known as the "bag and spoon" process. As the ground is excavated, the cylinder sinks gently into the river-bed ; as it descends, additional rings of plates are from time time added to it at the top. When in this way the cylinder has become 20 feet in length, plates shelving inwards are attached to the top of it, which reduce the diameter from 18 feet to 12 feet. This diameter of 12 feet is thenceforward the size of the cylinder, and consequently above low-water mark, it appears as a pillar 12 feet in diameter. The object of this arrangement is to get as large a base as possible without having an unsightly appearance above water, and to avoid undue interference with the waterway of the river. Great care is necessary throughout the proceedings to keep the cylinders upright in their position, and strong timber shoring and strutting is employed for this purpose. The cylinder passes gradually down through the mud and silt till the London clay is reached, when the process of sinking is entirely altered.
The bottom of the cylinder being once well into the London clay, a steam pump is introduced, the water inside the cylinder is pumped out, and the ground at the bottom exposed to view. Navvies are then employed to continue the excavation, which proceeds thenceforward with speed and regularity till the bottom of the cylinder has reached a depth of between fifty and sixty feet below high-water mark. At this depth the London clay generally presents such a degree of hardness and consistency as satisfies the engineer, and thereupon the interior of the cylinder is filled up with concrete made with Portland cement, to the level of about 13 feet below low-water. This point corresponds with the bottom of the shelving-plates, which, as we have said, reduce the diameter of the cylinder from 18 feet to 12 feet. On the top of the concrete, brickwork in Portland cement is built to a few feet above low-water, and then a weight of 800 to 830 tons of iron, as a test, is placed on the top. This weight placed represents the pressure which would be brought to bear upon the foundation, supposing the whole area of the bridge, with its five lines of rail, was closely packed with tank locomotive engines. The testing being performed, the cylinder-plates are again continued to the underside of the girders of the superstructure, and the brickwork is also continued to within 2 feet of the same point. 'Large granite bearing-stones are then placed on the top of the brickwork, and the cylinder, with the exception of the ornamental capital, mav then be said to be complete.

'The bridge stands on four piers, each of which is formed of four boldly-fluted cylinders, arranged at right angles to the axis of the bridge. There are, therefore, sixteen cylinders in all. The spans, or openings, are consequently five in number. The two nearest each bank of the river are 125 feet wide in the clear, and the remaining three are 136 feet wide in the clear. The headway, or height of the bottom of the girders above high water-mark, varies from 24 1/2 feet at the side spans to 25 feet at the centre span. The superstructure of the bridge is unlike the Charing-cross bridge, inasmuch as the girders are all arranged longitudinally under the railway instead of their being girders at the side of the bridge, and cross girders supported by them. These girders are 8 feet 6 inches in depth, and the ends rest upon transverse box girders placed on the top of iron columns. There are to be five lines of railway on the bridge, and two footpaths, one on each side. The total minimum width of the bridge will be 80 feet, the same as the new Westminster-bridge.

'The tops of the cylinders will be ornamented with moulded capitals, differing in this respect from the bridge at Hungerford, which makes no pretence to architectural ornament or effect, and which is simply an engineering bridge, and does not possess an ounce of metal that is not really required for the structural part of the works. The footpaths on each side will be carried by means of richly moulded cantilevers, projecting some 8 feet beyond the face of the outside girders; a handsome cast-iron pierced parapet will protect the foot-passengers, and add greatly to the generally ornamental character of the bridge. The overhanging footpaths and cantilevers will produce a striking and novel effect, and the deep shadow underneath them will give character to the whole structure.

'Between the pier nearest the Middlesex abutment and the abutment itself the bridge widens out in the form of a fan from 80 to 201 feet in width, to accommodate the numerous curves necessary on approaching the station. The quantity of cast iron used on the bridge will be about 3,000 tons, and the weight of wrought iron nearly 3,500 tons.

'The superficial area of the Cannon-street-bridge is larger than that of the London, Chatham, and Dover bridge at Blackfriars, in the proportion of about four to three.

'The station — with which is combined an hotel — now in course of erection between the river and Cannon-street, has a substructure, formed entirely of brick arches, except where the important thoroughfare of Upper Thames-street passes underneath it, about midway of the length of the station, where the levels necessitate the employment of wrought iron girders. ..... Mr. Hawkshaw, as we have stated, is the engineer to the Charing-cross Railway Company, and the works are being executed Mr. George Wythes, as contractor, the iron-work on the line being supplied by Messrs. Cochrane, Grove, and Co., of Dudley. Mr. John Barry, one of the sons of Sir Charles Barry, is the resident engineer of the line.'

See Cannon Street Railway Station for the rest of this article.

1865 The roof of the station is a great work in iron, immense as it is in its span. It consists of nineteen principal, with as many intermediate, ribs averaging about 34ft. between centres, exclusive of the principal terminals. The tension rods of the principals, although 5 3/4in. diameter, look, when in their places, as only as many stout wires. Tbe principals have struts from the rib to the tension rod from 4ft. to 30ft., with diagonal bracing in addition. The roof has intermediate purlines of lattice bracing. We should here state, perhaps, that the contract is being executed by Messrs. Cochrane, of Woodside, Staffordshire, under engagement to Mr. Wythes, contractor for the whole work, and that the delay in its execution, of which public complaint has been made, is attributable neither to one nor the other of the parties referred to but to causes beyond their control. This we can safely say, that on visiting repeatedly the bridge and station, we found as many hands employed as had room to work - 150 hands at the station, and about 200 at the bridge, with about a dozen steam engines to help them, and Mr. Wythes, ever ready with his able henchman, Mr. Canning, doing their best to facilitate the completion of this great undertaking.

1926 'GREAT CANNON-ST BRIDGE WIDENING. WINTRY NIGHT WORK.
Railway engineers have been working steadily through the night on Cannon-street Bridge, at the task a placing in position a 72 ton girder, over 140 feet long. which is to bear the weight of the two extra rail-roads that will serve the station.
DROP OF 11 FEET. This evening the great mass of metal, swivelled into position during last night, will be lowered 11 feet on to the distributing girders that will bear its weight, and the new roads and the platform, that were dismantled last night to allow the girder to pass, will be laid over it. At midnight the men were working in the light of acetylene flares. Thin snow was falling. Ihe girder, built up beside the platform during the last fortnight, was pivoted at one end. The other rested on a small trolley. Rails were laid rapidly as the platform was taken down for the passage in the early hours of the trolley and its great load, drawn by powerful winches.'

See here for a good overview of the bridge's history up to 1966, from which: 'The superstructure consists of free-span plate girders in the two shore openings and continuous plate girders 442 ft. 6 in. long over the three middle spans. ... Increasing traffic made it necessary to widen the approach bridge over the river, and this work was begun in 1886 on the western (up-stream) side. The enlarged bridge, with ten roads, was brought into use on February 13, 1892, increasing the width to about 120 ft., but all the work was not completed until the first half of 1893. It was (and is) carried on piers of six cast-iron columns, of which the four downstream are the originals of 1865, and the two upstream those of the widening. .... '

An 1890-1900 drawing here of the fanned out approach girders shows five new girders inserted between some of the eight original girders, plus one new girder on the downstream side of the existing girders. The new girders were to be seated on shallow riveted cross girders, filled with cement, supported on Bramley bedstones seated on new brickwork.

A strengthening programme was undertaken between 1909 and 1913.

See Also

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Sources of Information

• [3] Wikipedia