Tuesday 14th October 2014
The History of London Bridge and the Demolition and Reconstruction of the present Bridge
Mr Frank Duggan RCEA
Frank was employed on London Bridge from 1968 – 1970 and his illustrated talk encompassed his experience of working on site on the demolition and reconstruction of the present bridge. He also covered the history of nearly 2000 years of river crossings on the site and the demolition of the old bridge and its reconstruction 4300 miles away in Lake Havasu City, Arizona.
History: The first bridge was probably a Roman military pontoon type, giving a rapid overland shortcut to Camulodunum from the southern and Kentish ports, along the Roman roads of Stane Street and Watling Street (the A2). Around AD 55, this temporary bridge was replaced by a permanent timber piled bridge, maintained and guarded by a small garrison. The bridge was probably destroyed along with the town in the Boudican revolt (60 AD). Both were rebuilt and Londinium became the administrative and mercantile capital of Roman Britain.
With the end of Roman rule in Britain in the early 5th century, Londinium was gradually abandoned and the bridge fell into disrepair. The history is then a bit hazy until the earliest contemporary written reference to a Saxon bridge in c.1016 when chroniclers mention how Cnut’s ships bypassed the crossing, during his war to regain the throne from Edmund Ironside. Following the Norman conquest of England in 1066 the bridge was repaired then rebuilt and in 1163 the bridge was rebuilt using timber for the last time.
After the murder of Thomas Becket, Archbishop of Canterbury, the penitent King Henry II commissioned a new stone bridge in place of the old, with a chapel at its centre dedicated to Becket as a martyr. It was grander than some town parish churches, and had an additional river-level entrance for fishermen and ferrymen. Building work began in 1176 and it was finished by 1209 during the reign of King John. John licensed out building plots on the bridge to help recoup the costs. The buildings (138 shops by 1358) were a major fire hazard resulting in many fires also they increased the load on its arches, several of which had to be rebuilt over the centuries
By the Tudor era there were some 200 buildings on the bridge. Some stood up to seven stories high, some overhung the river by seven feet, and some overhung the road, to form a dark tunnel through which all traffic must pass, including (from 1577) the palatial Nonsuch House. The roadway was just 12 feet (4 m) wide, divided into two lanes, so that in each direction, carts, wagons, coaches and pedestrians shared a passageway six feet wide.
The narrow arches and wide pier bases restricted the river’s tidal ebb and flow, so that in hard winters, the water upstream of the bridge became more susceptible to freezing and impassable by boat. The flow was further obstructed in the 16th century by waterwheels installed under the two north arches to drive water pumps, and under the two south arches to power grain mills; the difference in water levels on the two side of the bridge could be as much as six feet (two metres), producing ferocious rapids between the piers.
In 1758–62, all houses and shops on the bridge were demolished through an Act of Parliament and the two centre arches were replaced by a single wider span to improve navigation on the river.
‘Rennie’s Bridge’: By the end of the 18th century the old London Bridge – by then over 600 years old – needed to be replaced. It was narrow and decrepit, and blocked river traffic. In 1799, a competition for designs to replace the old bridge was held. Entrants included Thomas Telford, whose proposal of a single iron arch spanning 600 feet (180 m) was rejected as unfeasible and impractical. John Rennie won the competition with a more conventional design of five stone arches. It was built 100 feet (30 m) west (upstream) of the original site under the supervision of Rennie’s son.
Work began in 1824 and the foundation stone was laid, in the southern coffer dam, on 15 June 1825 with the official opening on 1st August 1831. Rennie’s bridge was 928 feet (283 m) long and 49 feet (15 m) wide, constructed from Haytor granite. New approach roads had to be built, which cost three times as much as the bridge itself. The total costs, around £2.5 million (£198 million in 2014), costs were shared by the British Government and the Corporation of London. The old bridge continued in use while the new bridge was being built, and was demolished after the latter opened in 1831.
In 1896 the bridge was the busiest point in London, and one of its most congested; 8,000 pedestrians and 900 vehicles crossed every hour. It was widened by 13 feet, using granite corbels. Subsequent surveys showed that the bridge was sinking an inch (about 2.5 cm) every eight years, and by 1924 the east side had sunk some three to four inches (about 9 cm) lower than the west side. The decision was taken to remove and replace the bridge.
Modern London Bridge: Frank described the design, planning and the construction of the current bridge which was designed by architect Lord Holford and engineers Mott, Hay and Anderson. It was constructed by contractors John Mowlem and Co from 1967 to 1972 at a cost of £4 million (£49.3 million in 2014). It was officially opened by Queen Elizabeth II on 17th March 1973.
The bridge comprises three spans of pre-stressed concrete box girders, a total of 928 feet (283 m) long and was built in the same location as Rennie’s bridge which had to remain in use during the build programme. This resulted in the requirement for a very complicated and detailed build programme.
The construction method used was to install one span upstream and one span downstream while traffic used the original bridge. Traffic was then transferred onto the two new girders, and the previous bridge demolished to allow the final two central girders to be added.
Frank detailed excavating for the piers – some close to London Underground tunnels, and the building of the piers. The pre-stressed box girders were then barged from a nearby support site and lifted into position. Once all the girders were in position the roadway and pedestrian walkway were constructed. Once this was completed all of the lighting and ancillary services were completed.
Sale of Rennie’s London Bridge to Robert McCulloch: On 18 April 1968, Rennie’s bridge was sold to the Missourian entrepreneur Robert P. McCulloch of McCulloch Oil for US$2,460,000. The claim that McCulloch believed mistakenly that he was buying the more impressive Tower Bridge was denied by both McCulloch and Luckin (who sold the bridge) in a newspaper interview. As the bridge was taken apart, each piece was meticulously numbered. The blocks were then shipped overseas through the Panama Canal to California and trucked from Long Beach to Arizona.
The bridge was reconstructed by Sundt Construction at Lake Havasu City, Arizona and re-dedicated on 10 October 1971. The bridge consists of a concrete frame with facing stones from Rennie’s London Bridge used as cladding. Prior to re-cladding 15 to 20 cm (5.9 to 7.9 inches were sliced from the stones resulting in cladding 150 to 200mm (6 to 8 inches) thick.
Frank’s talk was concluded with a question and answer session. An excellent overview of one of the most – (or maybe even the most!!) important London River Thames crossings.