Hammersmith Bridge
First Bridge
1825 a suspension bridge was designed by William Tierney Clark, who lived in the area and was Engineer to the West Middlesex Water Works Company. This was the first suspension bridge over the Thames.
To mark the start of the project, the design of which was approved by Thomas Telford, the Duke of Sussex fixed a brass plate to one of the foundation cofferdams. Clark estimated the cost of the bridge to be around £50,000.
The bridge was supported by two masonry river piers, founded on timber piles, with a clear waterway between them of 200 ft (122m). Ironwork was by Gospel Oak Ironworks, Birmingham; stonework was by G.W. & S. Bird, Hammersmith; decking/fencing by E.J. Lance, Lewisham
Above the piers were two towers with Tuscan-style arched entrances. Eight chains of wrought iron links hung from the towers, supporting the timber deck. The chain links had a cross section of 5" by 1" (127mm by 25mm). The carriageway was 20 ft (6.1m) wide with two 1.5m wide pavements, although narrower under the arches. The bridge was completed in 1827.
1869 Strength tests on the chains proved satisfactory.
The Present Bridge
A new suspension bridge was constructed to replace the old one.
1884 A temporary bridge was put in place because of heavier traffic. Clark's suspension bridge was then reconstructed by Sir Joseph Bazalgette based on Clark's river piers.
The new bridge had much stronger steel chains. The towers appear to have great mass, but in fact they are is assembled from rolled sections riveted together, and clad with ornamental iron castings (see Fig. 1887. 1.). The quality of foundrywork displayed in these castings is of a very high standard. The quality is such that it is not immediately obvious that the casings are formed from numerous thin castings joined together. It should be born in mind that the production of the individual castings would start with wooden patterns, made slightly oversize to allow for shrinkage as the molten iron solidifed and cooled. The patterns were used to produce the required shape in the sand moulds. There was ample scope for casting defects to arise, due for example to washing-away of the sand, the presence of blowholes in the casting, and distortion of the castings as they cooled. Good joints could be obtained by planing the edges of the castings, but obtaining smooth flat surfaces, sharp edges and details, and continuity of complex geometry between connected plates took considerable skill and experience. The thickness of plates ranged from 3/8" to 3/4". Referring to Fig 2023 2 above, small discrepancies are visible at the mouldings, but it should be noted that at least eleven separate castings come together where we see the inner and outer radii of the centre circle.
Details of construction were given in The Engineer in 1887 [1][2][3]. Parts of some of the drawings are reproduced above.
Extracts from 1887 articles: It was required that all chain links (eye bars) bars which were to be placed side by side in the structure of the chain should be bored at the same temperature, and of such equal length that upon being piled upon each other the pins should pass through the holes at both ends without driving. The 6" diameter pin holes were to be 1/30" larger than the diameter of the pin. The towers were bolted to the piers by long 1 3/4" bolts which passed through the masonry to terminate in anchor plates with chambers in the piers. The chains are connected to saddles on top of the towers. The saddles sit on rollers to accommodate expansion and contraction.
After the 1827 bridge was dismantled, chain links were used to aid construction of the Forth Bridge (not as part of the bridge, but for rigging, construction of temporary working platforms, etc).
Newspaper Reports
1882 'The New Bridge over the Thames.—The contract for the erection of a new suspension bridge over the Thames, at Hammersmith, has been secured by Messrs. Vernon and Ewens, of the Central Ironworks, Cheltenham. The bridge is about being erected by order of the Metropolitan Board of Works, from designs by their engineer and architect, Sir J. Bazalgette. The amount of the contract, under which the contractors remove and take to the old bridge, is about £80.000, and the work to be completed in two years, during which time a ferry will be maintained for the conveyance of passengers, &c, across the river. The new bridge will be very similar in design to the bridge it will replace, except that the towers will be of iron instead of Portland stone, in the present structure. The bridge will also be somewhat wider and higher and very considerably stronger. It will consist of three spans, the centre one of 400 ft., and the two side spans each of 145 ft. The width of the bridge will be 43ft. There will be nearly 1,000 tons of steel used its construction, besides wrought iron, and some 200 or 300 tons of ornamental cast iron work. The ornamentation will be somewhat elaborate, and will form a prominent feature of the structure. The old bridge, which is still in good, sound condition,— though not of sufficient strength to stand the strain a London crowd on boating days, on which occasions it has been usually closed,— will be in Messrs. Vernon and hands for disposal.'[4]
1884 Metropolitan Board of Works. .... The Board determined to terminate the contract of Messrs. Vernon and Ewen, for the reconstruction of Hammersmith-bridge.'[5]
1887 'THE NEW HAMMERSMITH BRIDGE.
The new bridge at Hammersmith, which has been in course of construction for over two years, will be opened to-day by Prince Albert Victor. The structure which it has replaced was built some sixty or seventy years ago, and with the extension of the metropolis its capacity had been decidedly out-grown. The new bridge has three spans, the centre one of which is 400 ft. long, and those at the side 143 ft. each. The centre span corresponds with that of the old bridge in length, but the headway is 15 ft. above Trinity high water mark, while the old one was only 11ft. The breadth has also been materially increased, the old measurement at the towers being 14 ft. for both foot and vehicular traffic, while the new carriage-way measures 19 ft. 9 in., and the footpaths which pass outside the piers 6 ft. each. At other parts of the bridge the roadway is 27 ft. broad. The towers of the old bridge were of solid stone and weighed about a thousand tons each, but as with the increased width a greater weight would have had to be provided for on the old foundations, which were utilized, it became necessary to lighten the superstructure of the piers by constructing them of iron.
On the Surrey side the foundations were so shallow as to be two feet above the bed of the river at ten feet distance, and it was therefore deemed essential to carry them down to an extra depth of six feet, and this was effected by underpinning. On the north side, where the river is shallower, the old foundations went down deeper, and they were not touched.
The bridge, which is suspended on chains, is somewhat remarkable for the size of the steel links employed, which were manufactured by Messrs. John Brown and Co., of Sheffield. Each link was rolled out of a steel ingot of the required size to its exact shape, leaving very little to be done in the way of dressing afterwards. The specified test was thirty tons to the square inch and on being tested by Messrs. Kirkaldy, of Southwark, they gave very satisfactory results both as to strength, and extension. The chains are supported on the piers by a wrought-iron construction of great strength, over which there is an ornamental cast-iron casing to improve the architectural appearance. At the abutments the ends of the chains have been fastened with great care. Large masses of concrete of the required shape were put in at the back of the old abutments. The chains are anchored in the new concrete by means of eight large steel forgings, each 13 inches in diameter and about 18 feet in length. [See Fig 1887. 5]. These are connected with the chains and pass through large iron castings and bear on York stones of a combined thickness of 3 feet. At the tops of the pier towers and at the abutments there are moveable saddles to which the chains are connected, and through which pass steel keys arranged in such a manner that the chains can be lengthened or shortemed for the purpose of adjusting the bridge. [See Figs. 1887 3 & 4]. The roadway is supported from the chains by means of suspension rods attached to cross girders, which are also attached to two longitudinal stiffening girders, which keep the bridge in shape and distribute isolated loads over a greater length of chain.
Before the demolition of the old bridge a temporary structure was thrown across the river on the west side. The old roadway was then stripped of its macadam and timbers, and the cross-girders and suspension rods were gradually detached from the chains and lowered into barges in the river. The old chains were then raised upon staging formed round the piers by means of hydraulic presses to a sufficient height to enable platforms to be thrown across the river, and upon which they rested. The old piers were then demolished, and the new wrought-iron piers - the ironwork of which had been prepared by the Thames Iron Works - were brought to the side in barges and built up. The links of the chain were next put together, commencing from the saddles - the work being done upon the platforms formed upon the old chains-until they were joined at the centre of each span.
The designers of the bridge were Sir Joseph and Mr. E. Bazalgette, and the contractors Messrs. Dixon and Thorne, the contract price being £82,000.'[6]
1887 ' .... The Metropolitan Board of Works accepted the contract Messrs. John Dixon, C. E., and Alfred Thorne, C.E., for the rebuilding the suspension bridge, at the latter end of 1884, and that firm at once commenced operations. The old bridge was entirely demolished, with the exception of the stone piers, which remain from the road way level, but have been underpinned. The old Tuscan towers have been replaced towers of ornamental Ironwork, and other noticeable features in the new bridge are that much stronger chains have been used, a wider roadway has been constructed, and overhanging footpaths have been formed on each side the towers. The old piers of the chain towers still remaining, the central span is the same as in the old bridge, viz., 400 feet 2 1/4 inches; the span from the Surrey shore to the south pier is 145 feet 9 inches; and from the Middlesex shore, 143 feet 6 inches. The towers are lattice structures of angle iron to support the chain saddles a height above the roadway of 40 feet, the chains having a curve of 33 feet versine. The width of the roadway is 30 feet and there is a footpath, 6 feet wide on each side, protected by an ironwork fencing which seems hardly high enough. A clear headway is given above high water of 15 feet. Vast foundations were laid in deep pits the north and south ends of the bridge, some ten thousand cube yards of concrete being used, and there is heavy iron anchorage for the purpose of securing the ends of the four chains. The anchorages are at depth of about 30 feet below the surface the approaches of the roads. The towers and abutment saddles, to admit a little motion for the expansion and contraction of the chains, are fixed in ornamental cast iron casings. The abutments look very high and unsightly, and the tower casings are bare imitations of stone. The four chains are of steel, 8 and 9 links side by side, alternately fixed at the joints by steel pins six inches diameter, and held in the saddles of the towers and abutments by keys to permit of adjusting. The roadway has a stiffening girder on each side, and there is footpath on both sides with a protecting parapet girder. The roadway is carried on cross girders of wrought iron, on which ten inches of creosoted Baltic timber is laid, and this is covered with 5-inch wood paving blocks, the footpaths being asphalted. The cost of the new bridge has been about £83,000, and it has been erected with remarkable expedition under the supervision of Mr. George Double, the energetic manager of Messrs. Dixon and Thorne, tho building having taken just two years, reckoning from the date of commencement. The old bridge lasted for 60 years, and it may be interesting to mention that the iron chains were found by testing to be as good as when new. The new chains are about eight times the strength of the old ones. ....'[7]
1939 'Hammersmith Bomb Outrage .... "As a result of the explosion early on Wednesday suspension chains and stiffening girder of the upstream side of the bridge have been seriously damaged. The bridge has been closed to vehicular traffic but pedestrians are allowed over the down-stream footway. A detailed survey is being made but it is not possible at present to say how long the bridge will remain closed to vehicular traffic". The explosions occurred soon after 1 am. A hairdresser, Mr M C Childs of Prebend Mansions, Chiswick High-road who was crossing the bridge noticed a small leather suit-case on the structure of the bridge. Opening the case he saw that it was smoking so he climbed through the structure on to the side of the bridge and threw the case into the water. An explosion which followed sent up a 60 feet column of water. Just afterwards there was a second and much more violent explosion causing havoc among the girders on the west side of the bridge. Windows were shattered in houses several hundred yards from the bridge. Behind a large wooden screen in the glare of arc-lights a gang of workmen were repairing the damage on Wednesday night .....' Two men were charged - William Browne and Edward J. Connell.[8]. See 1939 photo above.
1973 'Work begins this autumn on repairing and strengthening Hammersmith Bridge to restore the load restriction from its present five tons to its former 12 tons. The Greater London Council has placed a £900,000 contract for the replacement of the stiffening girders and the timber deck and minor remedial works. While work is in progress the bridge will remain open to traffic during the day but will be closed on certain nights of the week between 10pm and 6am. Because of this it will take about two and a half years to complete. It is not yet possible to say which dates will be involved. Notices will posted at each end of the bridge to give prior warning of each closure. The bridge will be open to pedestrians at all times and alternative routes across the river for vehicles will be sign-posted on the approach roads on both sides of the river. As the bridge is listed as being of architectural and historic interest great care will be taken to preserve its appearance The contract has been placed with Clarke Chapman-John Thompson Ltd. The work will be carried out by Carter-Horseley Engineers and will be supervised by the GLC's consulting engineers Rendel Palmer and Tritton.'[9]
Note: The original stiffening girders were of riveted construction. Fig. 11 shows that the replacement girders are welded and bolted.
1997 '... Hammersmith Bridge needed attention 25 years ago. The GLC spent more than £600,000 in 1972 replacing the main girders. Now it needs a further £5 million repairs and could be closed for two years. Obviously we can't blame the Victorian architects for failing to predict the huge increase in road traffic ...'[10]
1998 Planning Applications: 'Hammersmith Bridge. Replacement of Hammersmith tower bearings, strengthening of longitudinal stiffening trusses, replacement/modification of some of the hangers.'[11]
See Also
Sources of Information
- ↑ The Engineer 1887/04/22 pp.309 & 314a.
- ↑ The Engineer 1887/04/29 p.330-1
- ↑ The Engineer 1887/05/20 p.391ff.
- ↑ Gloucester Citizen - Thursday 14 September 1882
- ↑ Evening News (London) - Saturday 28 June 1884
- ↑ Pall Mall Gazette - Saturday 18 June 1887
- ↑ West London Observer - Saturday 23 April 1887
- ↑ Kensington News and West London Times - Friday 31 March 1939
- ↑ Hammersmith & Shepherds Bush Gazette - Thursday 30 August 1973
- ↑ Hammersmith & Shepherds Bush Gazette - Friday 7 March 1997
- ↑ Middlesex County Times - Friday 16 January 1998
- Engineering Timelines [1]