The medieval London Bridge had stood for centuries as the only dry Thames crossing in or around the city. The opening of Westminster Bridge in 1749 highlighted the restrictions and limitations of the ancient structure and the City Corporation decided to modernize it on its old foundations.
Old London Bridge contained many shops and houses, which restricted passage across the river. The naturalist Thomas Pennant wrote in the 18th century:
I well remember the street on London Bridge, narrow, darksome, and dangerous to passengers from the multitude of carriages: frequent arches of strong timber crossed the street, from the tops of the houses, to keep them together, and from falling in the river.
Work to modernize the old medieval bridge, whose foundations had been in place since the 12th century, was completed in 1762.
Despite the large financial outlay the changes proved inadequate and required continuous repair. In 1799 a competition was held for designs for an entirely new crossing to replace the existing one. Those received included a revolutionary single-span cast-iron bridge from Thomas Telford that allowed ships to pass under, and a double-bridge in a classical design by George Dance the Younger. Both required large amounts of property to be purchased and demolished for the approaches, were therefore considered too expensive, and no action was taken.
A report of 1800 into the need for improvements in the Port of London highlighted the limitations to navigation caused by the crossing. The narrow arches created a weir-effect, with a fall of up to five feet. In 1812 coal-boat owners petitioned the City for a new bridge, pointing out the regular loss of life, as well as inconvenience, caused by the ancient structure. With the fast-growing population of the metropolis the narrow roadway also caused congestion for carriage and pedestrian traffic. The narrow arches slowed the flow of the river, allowing it to freeze over during very cold winters. In 1813-14 the frozen river caused damage to the bridge.
Petitions continued to be submitted to both the City and Parliament but with little result. In 1816 the City Corporation decided to delay any decision until after Southwark Bridge, then under construction, had been opened. In 1821 prizes of between £100 and £250 were offered for the three best ideas for a new bridge, to be judged by a committee that included the architects John Nash, John Soane and Robert Smirke. Over fifty designs were received including one by the engineer John Rennie who was responsible for both Waterloo and Southwark bridges. The prizes for the best submissions were awarded but none of the winning entries were put into practice.
In the meantime an Act of Parliament was passed in 1822 to remove the bridge’s waterworks, which supplied river water to parts of the City, in order to improve navigation. At the same time a Parliamentary committee recommended the building of a completely new structure and that finally spurred the City’s Bridge House committee, responsible for its operation, into action.
A Bill for a new bridge was finally passed in 1823, to be paid for partly by the City of London Corporation and by the Treasury from coal tax, on the condition that it was wider than the previous bridge. Despite it not being a winning design, it was decided to proceed with Rennie’s rather conservative scheme for a plain, five-span structure, lacking the flair of Waterloo Bridge or engineering innovation of Southwark. Rennie had died in 1821, so the work went ahead in 1824 under the supervision of his sons, John Rennie (the Younger) and George. The contractors were Messrs Jolliffe & Banks, with whom the Rennies had a long working relationship, including the construction of Waterloo and Southwark Bridges. In order to keep the old bridge open for traffic during construction it was decided that the new one should be on a different alignment, about one hundred feet upstream.
Work began in March 1824 and the foundation stone laid by Lord Mayor John Garratt in June 1825. An inscription within the stone, translated from Latin, read:
The free course of the river being obstructed by the numerous piers of the ancient bridge, and the passage of boats and vessels through its narrow channels being often attended with danger and loss of life by reason of the force and rapidity of the current, the City of London, desirous of providing a remedy for this evil, and at the same time consulting the convenience of commerce in this vast emporium of all nations, under the sanction and with the liberal aid of Parliament, resolved to erect a bridge upon a foundation altogether new, with arches of a wider span, and of a character corresponding to the dignity and importance of this royal City; nor does any other time seem to be more suitable for such an undertaking than when in a period of universal peace, the British Empire flourishing in glory, wealth, population, and domestic union, is governed by a Prince the patron and encourager of the arts, under whose auspices the Metropolis has been daily advancing in elegance and splendour.
The new bridge consisted of five semi-elliptical arches of varying widths, made of granite from Devon and Scotland. At the time of completion the central arch, of over 152 feet in width and a rise of over 37 feet, was possibly the largest such arch anywhere. The final width of the roadway was 52 feet, a decision having been made during construction to increase it by six feet.