London Bridge
London Bridge, any of several successive structures spanning the River Thames between Borough High Street in Southwark and King William Street in the City of London.
Old London Bridge
The Old London Bridge of nursery rhyme fame dates from 1176, when Peter of Colechurch, a priest and chaplain of St. Mary’s of Colechurch, began construction of the foundation. Replacing a timber bridge (one of several built in late Roman and early medieval times), Peter’s structure was the first great stone arch bridge built in Britain. It was to consist of 19 pointed arches, each with a span of approximately 7 metres (24 feet), built on piers 6 metres (20 feet) wide; a 20th opening was designed to be spanned by a wooden drawbridge. The stone foundations of the piers were built inside cofferdams made by driving timber piles into the riverbed; these in turn were surrounded by starlings (loose stone filling enclosed by piles). As a result of obstructions encountered during pile driving, the span of the constructed arches actually varied from 5 to 10 metres (15 to 34 feet). In addition, the width of the protective starlings was so great that the total waterway was reduced to a quarter of its original width, and the tide roared through the narrow archways like a millrace. “Shooting the bridge” in a small boat became one of the thrills of Londoners.
In 1205 Peter of Colechurch died, and three other London citizens completed the bridge by 1209. Almost immediately the bridge became not only an important commercial crossing but also a choice business and residential site. Shops lined both sides of the roadway between the fortified gates at either end; houses were built above the shops, with 138 premises being recorded in 1358. Walkways and additional rooms were extended between the buildings, transforming the roadway into a tunnel-like passage through which merchants and other travelers bustled. In the 1580s, during Queen Elizabeth I’s reign, water mills were installed that added to the uproar.
The bridge became the site of calamities. Three years after its completion a huge fire destroyed all the buildings and killed as many as 3,000 people. But the houses (a source of income for the bridge) were quickly rebuilt, lining the 282-metre (926-foot) length of the bridge and reducing the carriageway to only 4 metres (12 feet). In 1282 five arches collapsed under the pressure of winter ice. These, too, were rebuilt, and the bridge, though often in a state of disrepair, survived as London’s sole crossing of the Thames until 1750. In that year Westminster Bridge opened, despite opposition from City merchants.
Shortly thereafter the City decided to repair Peter of Colechurch’s bridge, and the project was given to Charles Labelye, designer of the Westminster Bridge. By 1762 all the houses were removed, the carriageway was widened to 14 metres (46 feet), and the two central arches were replaced by one great arch at mid-span. The removal of the central pier led to serious erosion of the riverbed, and gravel was constantly poured to protect the remaining piers. Finally the maintenance became too much of a burden, and the City asked the renowned engineer John Rennie to design a wholly new structure several yards upstream.
New London Bridge
For the new structure, Rennie proposed five semielliptical stone arches, with the central span reaching 46 metres (150 feet), the next two 43 metres (140 feet), and the two shore spans 40 metres (130 feet). Rennie died in 1821 before work began, and the job was left to his two sons. George Rennie had actually made the design in 1820, but construction was conducted under John Rennie, Jr., beginning in 1824. In 1831 King William IV and Queen Adelaide arrived by water to celebrate the opening of the new bridge. Demolition of the ancient structure began that year, and by 1832 it disappeared, having served 622 years.
Rennie’s bridge survived less than 140 years. Between 1968 and 1971 its facing stone was dismantled and shipped across the Atlantic Ocean to the U.S. state of Arizona, where it was reerected on a five-span core of reinforced concrete to serve as a tourist attraction at the resort town of Lake Havasu City. The New London Bridge now crosses Lake Havasu behind Parker Dam, 155 miles (250 km) south of Hoover Dam on the Colorado River.
Modern London Bridge
The current London Bridge, built between 1968 and 1972, replaced Rennie’s stone arches with beams of prestressed concrete reaching 104 metres (340 feet) in the central span. Construction was carried out using the cantilever method, with segments being built outward from two piers, each segment tied to the previous one by high-strength steel tendons. In the centre the two cantilevers did not meet but stopped short, leaving a space into which the builders placed a concrete beam to complete the span. The design represents a major post-World War II innovation in bridge engineering, but the bridge itself is not of great historical significance.
David P. Billington