الجمعة، 29 نوفمبر 2019

London Bridge

Several bridges named London Bridge have spanned the River Thames between the City of London and Southwark, in central London. The current crossing, which opened to traffic in 1973, is a box girder bridge built from concrete and steel. It replaced a 19th-century stone-arched bridge, which in turn superseded a 600-year-old stone-built medieval structure. This was preceded by a succession of timber bridges, the first of which was built by the Roman founders of London.

The current bridge stands at the western end of the Pool of London and is positioned 30 metres (98 ft) upstream from previous alignments. The approaches to the medieval bridge were marked by the church of St Magnus-the-Martyr on the northern bank and by Southwark Cathedral on the southern shore. Until Putney Bridge opened in 1729, London Bridge was the only road-crossing of the Thames downstream of Kingston upon Thames. London Bridge has been depicted in its several forms, in art, literature, and songs, including the nursery rhyme "London Bridge Is Falling Down".

The modern bridge is owned and maintained by Bridge House Estates, an independent charity of medieval origin overseen by the City of London Corporation. It carries the A3 road, which is maintained by the Greater London Authority.[1] The crossing also delineates an area along the southern bank of the River Thames, between London Bridge and Tower Bridge, that has been designated as a business improvement district
History
Location
The abutments of modern London Bridge rest several metres above natural embankments of gravel, sand and clay. From the late Neolithic era the southern embankment formed a natural causeway above the surrounding swamp and marsh of the river's estuary; the northern ascended to higher ground at the present site of Cornhill. Between the embankments, the River Thames could have been crossed by ford when the tide was low, or ferry when it was high. Both embankments, particularly the northern, would have offered stable beachheads for boat traffic up and downstream – the Thames and its estuary were a major inland and Continental trade route from at least the 9th century BC.[3]

There is archaeological evidence for scattered Neolithic, Bronze Age and Iron Age settlement nearby, but until a bridge was built there, London did not exist.[4] A few miles upstream, beyond the river's upper tidal reach, two ancient fords were in use. These were apparently aligned with the course of Watling Street, which led into the heartlands of the Catuvellauni, Britain's most powerful tribe at the time of Caesar's invasion of 54 BC. Some time before Claudius's conquest of AD 43, power shifted to the Trinovantes, who held the region northeast of the Thames Estuary from a capital at Camulodunum, nowadays Colchester in Essex. Claudius imposed a major colonia at Camulodunum, and made it the capital city of the new Roman province of Britannia. The first London Bridge was built by the Romans as part of their road-building programme, to help consolidate their conquest.[5]

Roman bridges
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 (now the A2). Around AD 55, the temporary bridge over the Thames was replaced by a permanent timber piled bridge, maintained and guarded by a small garrison. On the relatively high, dry ground at the northern end of the bridge, a small, opportunistic trading and shipping settlement took root and grew into the town of Londinium.[6] A smaller settlement developed at the southern end of the bridge, in the area now known as Southwark. The bridge was probably destroyed along with the town in the Boudican revolt (AD 60), but both were rebuilt and Londinium became the administrative and mercantile capital of Roman Britain. The upstream fords and ferries remained in use but the bridge offered uninterrupted, mass movement of foot, horse, and wheeled traffic across the Thames, linking four major arterial road systems north of the Thames with four to the south. Just downstream of the bridge were substantial quays and depots, convenient to seagoing trade between Britain and the rest of the Roman Empire.[7][8]

Early medieval bridges
With the end of Roman rule in Britain in the early 5th century, Londinium was gradually abandoned and the bridge fell into disrepair. In the Anglo-Saxon period, the river became a boundary between the emergent, mutually hostile kingdoms of Mercia and Wessex. By the late 9th century, Danish invasions prompted at least a partial reoccupation of the site by the Saxons. The bridge may have been rebuilt by Alfred the Great soon after the Battle of Edington as part of Alfred's redevelopment of the area in his system of burhs,[9] or it may have been rebuilt around 990 under the Saxon king Æthelred the Unready to hasten his troop movements against Sweyn Forkbeard, father of Cnut the Great. A skaldic tradition describes the bridge's destruction in 1014 by Æthelred's ally Olaf,[10] to divide the Danish forces who held both the walled City of London and Southwark. The earliest contemporary written reference to a Saxon bridge is c.1016 when chroniclers mention how Cnut's ships bypassed the crossing, during his war to regain the throne from Edmund Ironside (see Battle of Brentford (1016)).

Following the Norman conquest in 1066, King William I rebuilt the bridge. The London tornado of 1091 destroyed it, also damaging St Mary-le-Bow.[11] It was repaired or replaced by King William II, destroyed by fire in 1136, and rebuilt in the reign of Stephen. Henry II created a monastic guild, the "Brethren of the Bridge", to oversee all work on London Bridge. In 1163 Peter of Colechurch, chaplain and warden of the bridge and its brethren, supervised the bridge's last rebuilding in timber.[12]

"Old" London Bridge (1209–1831)
After the murder of his erstwhile friend and later opponent 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 martyr. The archbishop had been a native Londoner and a popular figure. The Chapel of St Thomas on the Bridge became the official start of pilgrimage to his Canterbury shrine; it was grander than some town parish churches, and had an additional river-level entrance for fishermen and ferrymen. Building work began in 1176, supervised by Peter of Colechurch.[12] The costs would have been enormous; Henry's attempt to meet them with taxes on wool and sheepskins probably gave rise to a later legend that London Bridge was built on wool packs.[12] After Colechurch's death, Isembert, a French monk who was renowned as a bridge builder, was appointed by King John to complete the project.[13] Construction was not finished until 1209 during the reign of King John. John tried to recoup the cost of building and maintenance by licensing out building plots on the bridge but this was never enough. In 1284, in exchange for loans to Edward I, the City of London acquired the charter for the maintenance of the bridge, based on the duties and toll-rights of the former "Brethren of the Bridge".

The bridge was 26 feet (8 m) wide according to some records that were later disputed.[14][15] The structure was about 800–900 feet (240–270 m) long, supported by 19 irregularly spaced arches, founded on starlings set into the river-bed. It had a drawbridge to allow for the passage of tall ships, and defensive gatehouses at both ends. By 1358 it was already crowded with 138 shops. At least one two-entranced, multi-seated public latrine overhung the bridge parapets and discharged into the river below; so did an unknown number of private latrines reserved for Bridge householders or shopkeepers and bridge officials. In 1382–83 a new latrine was made (or an old one replaced) at considerable cost, at the northern end of the bridge.[16]

The buildings on London Bridge were a major fire hazard and increased the load on its arches, several of which had to be rebuilt over the centuries. In 1212, perhaps the greatest of the early fires of London broke out on both ends of the bridge simultaneously, trapping many people in the middle. Houses on the bridge were burnt during Wat Tyler's Peasants' Revolt in 1381 and during Jack Cade's rebellion in 1450. A major fire of 1633 that destroyed the northern third of the bridge formed a firebreak that prevented further damage to the bridge during the Great Fire of London (1666).
By the Tudor period there were some 200 buildings on the bridge. Some stood up to seven storeys high, some overhung the river by seven feet, and some overhung the road, to form a dark tunnel through which all traffic had to pass; this did not prevent the addition, in 1577, of the palatial Nonsuch House to the buildings that crowded the bridge. The available roadway was just 12 feet (4 m) wide, divided into two lanes, so that in each direction, carts, wagons, coaches and pedestrians shared a single file lane six feet wide. When the bridge was congested, crossing it could take up to an hour. Those who could afford the fare might prefer to cross by ferry, but the bridge structure had several undesirable effects on river traffic. The narrow arches and wide pier bases restricted the river's tidal ebb and flow, so that in hard winters, the river upstream of the bridge became more susceptible to freezing and impassable by boat. The flow was further obstructed in the 16th century by waterwheels (designed by Peter Morice) 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 sides of the bridge could be as much as 6 feet (2 m), producing ferocious rapids between the piers resembling a weir.[17] Only the brave or foolhardy attempted to "shoot the bridge"—steer a boat between the starlings when in flood—and some were drowned in the attempt. The bridge was "for wise men to pass over, and for fools to pass under."[18]

The southern gatehouse became the scene of one of London's most notorious sights — a display of the severed heads of traitors, impaled on pikes[19] and dipped in tar and boiled to preserve them against the elements. The head of William Wallace was the first to appear on the gate, in 1305, starting a tradition that was to continue for another 355 years. Other famous heads on pikes included those of Jack Cade in 1450, Thomas More in 1535, Bishop John Fisher in the same year, and Thomas Cromwell in 1540. In 1598, a German visitor to London, Paul Hentzner, counted over 30 heads on the bridge:[20]

On the south is a bridge of stone eight hundred feet in length, of wonderful work; it is supported upon twenty piers of square stone, sixty feet high and thirty broad, joined by arches of about twenty feet diameter. The whole is covered on each side with houses so disposed as to have the appearance of a continued street, not at all of a bridge. Upon this is built a tower, on whose top the heads of such as have been executed for high treason are placed on iron spikes: we counted above thirty.

Evelyn's Diary noted that the practice stopped in 1660, following the Restoration of King Charles II,[21] but heads were reported at the site as late as 1772.[22] In 1666, the Great Fire of London first destroyed the bridge's waterwheels, preventing them from pumping water to fight the fire, and then burned one third of the houses on the bridge; a gap in the building left by a previous fire in 1633 prevented the destruction of the rest.
Over the years, incidents of arches collapsing were recorded in 1281–82 and in 1437. A survey in 1683 provided specifics as to the bridge's dimensions, stating that it had been 15 feet wide but was recently widened to 20 feet.[24] Considering the houses, the width actually available for traffic however, was only about 12 feet.[25][26]

A recently rediscovered list of leases from the 17th century provided a great deal of information, including the size and location of the 124 houses, the chapel, the gate and the drawbridge tower.[27] By 1710, most of the houses on the bridge had been rebuilt in the Restoration style and in order to widen the roadway to 20 feet (6 metres), the new houses were built overhanging the river supported by wooden girders and struts which hid the tops of the arches.[28] In 1722 congestion was becoming so serious that the Lord Mayor decreed that "all carts, coaches and other carriages coming out of Southwark into this City do keep all along the west side of the said bridge: and all carts and coaches going out of the City do keep along the east side of the said bridge." This has been suggested as one possible origin for the practice of traffic in Britain driving on the left.[29]

A fire in September 1725 destroyed houses on the bridge's east side and damaged some on the west side; they were rebuilt.[30] The last houses to be built on the bridge were designed by George Dance the Elder in 1745,[31] but even these elegant buildings had begun to subside within a decade.[32] In 1756, the London Bridge Act gave the City Corporation the power to purchase all the properties on the bridge so that they could be demolished and the bridge improved. While this work was underway, a temporary wooden bridge was constructed to the west of London Bridge. It opened in October 1757 but caught fire and collapsed in the following April. The old bridge was reopened until a new wooden construction could be completed a year later.[33] To help improve navigation under the bridge, its two centre arches were replaced by a single wider span, the Great Arch, in 1759.

Demolition of the houses was completed in 1762 and the last tenant departed after some 550 years of housing on the bridge.[34] Under the supervision of Dance the Elder, the roadway was widened to 46 feet (14 metres)[35] and a balustrade was added "in the Gothic taste" together with fourteen stone alcoves for pedestrians to shelter in.[36] However, the creation of the Great Arch had weakened the rest of the structure and constant expensive repairs were required in the following decades; this, combined with congestion both on and under bridge, often leading to fatal accidents, resulted in public pressure for a modern replacement
In 1799, a competition was opened to design a replacement for the medieval bridge. Entrants included Thomas Telford; he proposed a single iron arch span of 600 feet (180 m), with 65 feet (20 m) centre clearance beneath it for masted river traffic. His design was accepted as safe and practicable, following expert testimony.[38] Preliminary surveys and works were begun, but Telford's design required exceptionally wide approaches and the extensive use of multiple, steeply inclined planes, which would have required the purchase and demolition of valuable adjacent properties.[39] A more conventional design of five stone arches, by John Rennie, was chosen instead. It was built 100 feet (30 m) west (upstream) of the original site by Jolliffe and Banks of Merstham, Surrey,[40] 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

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