Windsor Town Bridge
The Windsor Town Bridge, or Windsor Bridge, crosses the River Thames, connecting Windsor and Eton, and carries pedestrian and cycle traffic.
The corner stone was laid in July 1822, and the bridge opened in June 1824.
The bridge has three arches, each comprising seven cast iron segments, and is supported in mid-stream by two granite piers. Two spans of 43 ft (13.1 m), one of 56 ft (17.1 m).
See Wikipedia entry.
Designer: Charles Hollis
Contractors: Moore, Jones and Fowler [1]
1823 'The death of Mr. William Moore, the contractor for building the new bridge at Windsor, will not interrupt the completion of the work. The land pier of the bridge is but recently finished, and the whole of the iron work of two arches out of the three, of which the bridge is composed, are yet be erected ; but the public will doubtless be glad to hear, that Mr. Moore’s executor has engaged to fulfil the remaining part of the contract with all possible despatch, and, as an earnest of his intention, has engaged double the number of men at present employed.'[2]. Note: William Moore (d. Octorber 1823) of Church Street, Westminster,was described as a stonemason.[3]
1824 'Yesterday the main rib of iron was placed in the centre arch of Windsor and Eton-bridge. The two former ribs made for the purpose having by accident been broken on their arrival, which materially retarded the finishing of the bridge. Notwithstanding this accident, it is expected that it will be complete and thrown open for passengers by the middle of the present month.'[4]
See here for a history of the bridge.
Note: Brunel's Windsor Railway Bridge is a short distance upstream.
Aspects of Design and Construction
The cast iron arch ribs are 18" deep, and are of I-section, albeit with small flange width. The spandrels are cast integral with the ribs (Fig. 4), an unusual feature when combined with relatively deep I-beams of early date. The outermost ribs differ from the inner ribs in having more substantial 'moulded' outer flanges for the sake of appearance.
Each rib is cast in three sections, with bolted flanges at the abutting ends (see Figs 3 & 6). A transverse plate, pierced by triangular openings, and spanning the full width of the bridge, is sandwiched between the bolted flanges (Fig. 6). The ribs are also braced transversely at the crown by horizontal x-braced cast iron frame (Fig. 3), and braced elsewhere by an unusual arrangement having rectangular frames which are bolted to the beams' webs, through the middle of which is a tie bar (Fig. 4), tensioned by a turnbuckle (see Fig. 5). The tie bars pass through the outer ribs, and the ends are peened over (heads are just visible on the left and right of the rib face in photo 7).
Diagonal bracing between ribs is also provided, having cast iron bars of cruciform section bolted to the webs of the ribs (Fig. 4). In Fig. 7 a joint between sections of arch rib is visible.
The standard of foundry moulding is not high, and the expenditure on patterns was evidently modest.
Charles Hollis went on to design Bigsweir Bridge, which has an impressive single cast iron arch of considerably larger span than at Windsor. Some of the design features are similar, but the spandrels are separate castings, and the characteristic 'tied frames' between the beams' webs are not included at Bigsweir. The standard of foundrywork is similar, and the foundry has not been identified for either bridge. Both bridges make limited use of threaded fasteners, and those used are of minimal size.