Rennie’s Waterloo Bridge across the Thames in London, completed in 1817 was considered by some to be his career masterpiece, described as ‘perhaps the finest large masonry bridge ever built in this or any other country’. Samuel Smiles in his Lives of the Engineers considered that it was ‘indeed a noble work, and probably has not its equal for magnitude, beauty and solidity’. The Italian sculptor Canova called it ‘the noblest bridge in the world’ and said that ‘it is worth going to England solely to see Rennie’s bridge.’
The end of the 18th century was a period of growing wealth, trade and financial speculation. London was enlarging rapidly yet there were still only three bridges across the Thames in the centre of the city: Old London Bridge, Westminster and Blackfriars. A group of speculators formed the Strand Building Company with the object of constructing a new toll bridge mid-way between London and Westminster Bridge and were confident it would soon be paid for with the profits from the tolls.
In 1810, Rennie was commissioned to produce a design for the new bridge. The northern abutments were to be alongside Somerset House, then a much more imposing building dominating the riverside, and he wanted his bridge to complement its style and grandeur. In the earlier part of his career, Rennie had developed his preferred approach to large stone bridges with the construction of the Lune, Dundas and Avoncliff Aqueducts as well as road bridges at Kelso, Radcliffe and the Wolsey Bridge in Staffordshire.
Thus when in 1806 a proposal was brought forward for a new bridge across the River Thames in London by a group of promoters called the Strand Bridge Company, Rennie had considerable experience and a sound reputation in the field. The Strand Bridge scheme was based on a design by George Dodd, one of a family of speculative engineers. Further plans were issued in 1807 but failed to gain parliamentary approval.
Because of worries about Dodd’s lack of experience in projects of this magnitude, his plans were referred to Rennie and William Jessop for a second opinion on 12 January 1809. Though he had been the leading canal engineer of the 1790s, the choice of Jessop was slightly odd as masonry bridges were not his forté. Although they had cooperated several times on canal schemes they had disagreed publicly more than once on the relative importance of economy and durability in civil engineering works. Nevertheless, they produced a joint report on 20 February which reviewed Dodd’s designs and proposed some substantial changes.
The promoters meanwhile had returned to parliament and were successful this time in gaining their Act on 20 June 1809. It laid down certain parameters that constrained the design including a clear waterway of not less than 1080 ft (329·2 m) and spans of at least 120 ft (36·6 m) span. The Bridge would have to leave the river at a much higher level than the ground on the Surrey (south) side, necessitating either a long approach viaduct or a short steep section. At the Middlesex (north) end the roadway was not to come nearer to Somerset House than 60 ft (18·3 m).
Little progress was made until a year later when Rennie was appointed engineer to the company. Even at this late stage, the precise line of the bridge was not fixed. Dodd’s plans were inaccurate and so almost immediately Rennie had the area resurveyed and settled on a new line, paying particular attention to the direction of the current in the river in order that the bridge should cross it as nearly as right angles as possible.
The design of the bridge adopted an elegant elliptical shape for the arches, creating a flatter bridge with easier gradients for travellers. Rennie added ornamentation in the form of his, by now trademark, Doric columns at each pier just as he had done for Kelso Bridge nearly twenty years before.
Rennie’s Waterloo Bridge was built by Jolliffe & Banks from 1811–1817 under what was then the largest, and most expensive, bridge contract ever undertaken in Britain.
Excavations for the foundations began in 1811 and the construction site became a popular visitor attraction, with even Tsar Alexander I making several visits to watch the work. The foundations were laid within cofferdams and the piles driven by steam engines. The cutwaters in plan were Gothic Arches, the shape which Rennie had come to prefer. Steady progress was made such that the abutment and first pier on the Surrey side was completed by March 1812. Meanwhile cofferdams for the next piers were progressing. By June 1812 Rennie was reporting stated that he expected to complete the arches by November 1815 and to have the bridge passable shortly thereafter.
Despite the good progress, the committee asked Rennie to consider using cast iron for the superstructure instead of stone, in order to save cost, a suggestion which Rennie rejected on the grounds of the aspiration to create a magnificent structure and manage future maintenance costs.
Problems began to be encountered as he project progressed including difficulties in land negotiations with the Duchy of Lancaster and the discovery of old sand dredging trenches and human remains around the foundations of the third pier. Storm damage in October 1812 caused further delays. Six months later, quicksand was found in the location of the eighth pier and around the foundations of Somerset House. Nonetheless progress continued and by 1813 construction of the stone arches was underway.
Rennie came under pressure from a meeting of the company for giving instructions to contractors for additional works without consulting the committee. He pointed out that extra works might need to be undertaken without waiting for a committee meeting if delays and consequential extra costs were to be avoided, but agreed that he would seek the committee’s approval to extras that were not urgent on the basis that the committee would have to take responsibility for all such decisions. At around the same time he wrote to the contractors to remind them that no work would be deemed extra to the contract (and therefore eligible for additional payment) without a specific instruction.
Issues with the supply of stone from Cornwall led to the use of some granite from an alternative source, Craigleith, near Edinburgh, for the middle parts of the arches, as it was not very different in colour.
On 7 May 1814, the central keystone of the first arch was placed in position, ‘fitting in as if it had been made on the spot, giving general satisfaction to all concerned’, as George Rennie noted.
The bridge was completed and opened on 18 June 1817, the second anniversary of the Battle of Waterloo. The ceremony was conducted with great pomp by the Prince Regent, with the Duke of Wellington in attendance. Rennie was offered a knighthood, which he rejected.
After Waterloo Bridge only a handful of large masonry road bridges were built in Britain.
The bridge was demolished in the 1930s following subsidence of the foundations under one of the piers and the need for a bridge with greater road capacity to meet the growing traffic flows.