Misplaced Pages

#515484

59-679: The Millennium Bridge , officially known as the London Millennium Footbridge , is a steel suspension bridge for pedestrians crossing the River Thames in London, England, linking Bankside with the City of London . It is owned and maintained by Bridge House Estates , a charitable trust overseen by the City of London Corporation . Construction began in 1998, and it initially opened on 10 June 2000. Londoners nicknamed it

118-410: A cable-stayed bridge in which the deck is in compression. Cable-stayed bridges and suspension bridges may appear to be similar, but are quite different in principle and in their construction. In suspension bridges, large main cables (normally two) hang between the towers and are anchored at each end to the ground. The main cables, which are free to move on bearings in the towers, bear the load of

177-460: A 200 feet span (also termed Beose Bridge) was constructed near Sagar, India during 1828–1830 by Duncan Presgrave, Mint and Assay Master. The Clifton Suspension Bridge (designed in 1831, completed in 1864 with a 214 m central span), is similar to the Sagar bridge. It is one of the longest of the parabolic arc chain type. The current Marlow suspension bridge was designed by William Tierney Clark and

236-473: A battle was a common practice in most European countries for centuries, and was even carried over into the new world as recently as the American War of Independence . Since then, it has been phased out by advances in military equipment and tactics ; however, foot drill remains an important part of military education and training . The following commands specify different types of marching: The way

295-492: A bridge has a tendency to collapse simply because of the gravitational forces acting on the materials of which the bridge is made. Live load refers to traffic that moves across the bridge as well as normal environmental factors such as changes in temperature, precipitation, and winds. Dynamic load refers to environmental factors that go beyond normal weather conditions, factors such as sudden gusts of wind and earthquakes. All three factors must be taken into consideration when building

354-468: A bridge. Silver Bridge (USA) was an eyebar chain highway bridge, built in 1928, that collapsed in late 1967, killing forty-six people. The bridge had a low-redundancy design that was difficult to inspect. The collapse inspired legislation to ensure that older bridges were regularly inspected and maintained. Following the collapse a bridge of similar design was immediately closed and eventually demolished. A second similarly-designed bridge had been built with

413-788: A bridge. The principles of suspension used on a large scale also appear in contexts less dramatic than road or rail bridges. Light cable suspension may prove less expensive and seem more elegant for a cycle or footbridge than strong girder supports. An example of this is the Nescio Bridge in the Netherlands, and the Roebling designed 1904 Riegelsville suspension pedestrian bridge across the Delaware River in Pennsylvania. The longest pedestrian suspension bridge, which spans

472-403: A higher margin of safety and remained in service until 1991. The Tacoma Narrows Bridge , (USA), 1940, was vulnerable to structural vibration in sustained and moderately strong winds due to its plate-girder deck structure. Wind caused a phenomenon called aeroelastic fluttering that led to its collapse only months after completion. The collapse was captured on film. There were no human deaths in

531-662: A licence for the structure, and the City of London and London Borough of Southwark granting planning permission . Construction began in late 1998, and the main works were started on 28 April 1999 by Monberg & Thorsen and Sir Robert McAlpine . The eventual cost was £18.2 million (£2.2m over budget), primarily paid for by the Millennium Commission and the London Bridge Trust. The bridge opened on 10 June 2000, one month late. Unexpected lateral vibration due to resonant structural response caused

590-568: A pedestrian suspension bridge over the Machchhu River in the city of Morbi, Gujarat, India collapsed, leading to the deaths of at least 141 people. Military step The steady, regular marching step was a marked feature of Roman legions . Vegetius , the author of the only surviving treatise on the Roman Empire's military, De Re Militari , recognized the importance of: constant practice of marching quick and together. Nor

649-619: A platform lift. Suspension bridge A suspension bridge is a type of bridge in which the deck is hung below suspension cables on vertical suspenders. The first modern examples of this type of bridge were built in the early 1800s. Simple suspension bridges , which lack vertical suspenders, have a long history in many mountainous parts of the world. Besides the bridge type most commonly called suspension bridges, covered in this article, there are other types of suspension bridges . The type covered here has cables suspended between towers , with vertical suspender cables that transfer

SECTION 10

#1732802168516

708-647: A proposal by Robert Stevenson for a bridge over the River Almond near Edinburgh . Roebling's Delaware Aqueduct (begun 1847) consists of three sections supported by cables. The timber structure essentially hides the cables; and from a quick view, it is not immediately apparent that it is even a suspension bridge. The main suspension cables in older bridges were often made from a chain or linked bars, but modern bridge cables are made from multiple strands of wire. This not only adds strength but improves reliability (often called redundancy in engineering terms) because

767-541: A sequence generally described as follows. Depending on length and size, construction may take anywhere between a year and a half (construction on the original Tacoma Narrows Bridge took only 19 months) up to as long as a decade (the Akashi-Kaikyō Bridge's construction began in May 1986 and was opened in May 1998 – a total of twelve years). Suspension bridges are typically ranked by the length of their main span. These are

826-442: A sign dating from 1873 warning marching ranks of soldiers to break step while crossing. The bridge's movements were caused by a positive feedback phenomenon, known as synchronous lateral excitation . The natural sway motion of people walking caused small sideways oscillations in the bridge, which in turn caused people on the bridge to sway in step, increasing the amplitude of the bridge oscillations and continually reinforcing

885-499: A temporary walkway. Poured sockets are used to make a high strength, permanent cable termination. They are created by inserting the suspender wire rope (at the bridge deck supports) into the narrow end of a conical cavity which is oriented in-line with the intended direction of strain. The individual wires are splayed out inside the cone or 'capel', and the cone is then filled with molten lead-antimony-tin (Pb80Sb15Sn5) solder. Most suspension bridges have open truss structures to support

944-547: A total structure length of 325 m (1,066 ft); the aluminium deck is 4 m (13 ft) wide. The eight suspension cables are tensioned to pull with a force of 2,000  tons against the piers set into each bank—enough to support a working load of 5,000 people. Ordinarily, bridges across the River Thames require an Act of Parliament. For this bridge, that was avoided by the Port of London Authority granting

1003-510: A unit marches is based upon the unit's nationality, role and history. Most Western Bloc nations currently have similar quick marching styles of lifting their legs in a natural or casual manner. Former Eastern Bloc nations and several Latin American, Asian and African nations use or have used the goose step , with legs remaining straight during each step. Both of these function to maintain individual pace, unit pace uniformity, and actually help

1062-550: Is anything of more consequence either on the march or in the line than that they should keep their ranks with the greatest exactness. For troops who march in an irregular and disorderly manner are always in great danger of being defeated. They should march with the common military step twenty miles in five summer-hours, and with the full step, which is quicker, twenty-four miles in the same number of hours. If they exceed this pace, they no longer march but run, and no certain rate can be assigned. Military marching of foot formations into

1121-645: Is considered the last remaining Inca rope bridge and is rebuilt annually. The first iron chain suspension bridge in the Western world was the Jacob's Creek Bridge (1801) in Westmoreland County, Pennsylvania , designed by inventor James Finley . Finley's bridge was the first to incorporate all of the necessary components of a modern suspension bridge, including a suspended deck which hung by trusses. Finley patented his design in 1808, and published it in

1180-591: Is near the Globe Theatre , the Bankside Gallery , and Tate Modern , while its northern end is next to the City of London School below St Paul's Cathedral . The bridge's alignment is such that a clear view (i.e. a " terminating vista ") of St Paul's south façade is presented from across the river, framed by the bridge supports. An architectural design competition was organised in 1996 by Southwark council and RIBA Competitions . The winning entry

1239-537: The "Wobbly Bridge" and even the " Wibbly Wobbly " after pedestrians experienced an alarming swaying motion on its opening day. The bridge was closed later that day and, after two days of limited access, it was closed again for almost two years so that modifications and repairs could be made to keep the bridge stable and stop the swaying motion. It reopened in February 2002. The bridge is located between Southwark Bridge and Blackfriars Railway Bridge . Its southern end

SECTION 20

#1732802168516

1298-836: The Mahakam River , located in Kutai Kartanegara Regency , East Kalimantan district on the Indonesia island of Borneo , was built in 1995, completed in 2001 and collapsed in 2011. Dozens of vehicles on the bridge fell into the Mahakam River . As a result of this incident, 24 people died and dozens of others were injured and were treated at the Aji Muhammad Parikesit Regional Hospital. Meanwhile, 12 people were reported missing, 31 people were seriously injured, and 8 people had minor injuries. Research findings indicate that

1357-681: The Millennium Inclinator , is next to the northern end of the Millennium Bridge. It was opened in December 2003 to allow pedestrians to surmount the steep slope (13.6°) of Peter's Hill from the riverside to the entrance to the Millennium Bridge without using the alternative flight of steps. The lower end of the lift is on Paul's Walk next to the Thames , and the top end is 26.85 metres (88.1 ft) further up Peter's Hill on

1416-488: The Thames Diamond Jubilee Pageant of 3 June 2012, which took place about a month before the 2012 Summer Olympics . The new lift was manufactured by Hütter Aufzüge of Glinde, Schleswig-Holstein , Germany, a lift manufacturer which was taken over by Otis in 2013. Axis Elevators installed the new equipment. Following a redevelopment of the area in 2021 the lift was closed and will be replaced by

1475-552: The University of Southampton and Imperial College London . Later in 2000, one span of the bridge was instrumented and tested with crowds of up to 275 people. They concluded that making the bridge stiffer, to move its resonant frequency out of the excitation range, was not feasible as it would greatly change its appearance. Instead, the resonance was controlled by retrofitting 37 viscous fluid dampers to dissipate energy. These include 17 chevron dampers – long V-shaped braces under

1534-448: The live and dead loads of the deck below, upon which traffic crosses. This arrangement allows the deck to be level or to arc upward for additional clearance. Like other suspension bridge types, this type often is constructed without the use of falsework . The suspension cables must be anchored at each end of the bridge, since any load applied to the bridge is transformed into tension in these main cables. The main cables continue beyond

1593-520: The City of London Planning and Transportation Committee decided that the level of service was unacceptable, because the inclinator was frequently out of service due to mechanical breakdowns and vandalism. So the Committee agreed it would be replaced at a cost of up to £750,000 in time for the 2012 Summer Paralympics . A major renovation project was undertaken in 2012, and the lift was reopened in time for

1652-777: The Philadelphia journal, The Port Folio , in 1810. Early British chain bridges included the Dryburgh Abbey Bridge (1817) and 137 m Union Bridge (1820), with spans rapidly increasing to 176 m with the Menai Bridge (1826), "the first important modern suspension bridge". The first chain bridge on the German speaking territories was the Chain Bridge in Nuremberg . The Sagar Iron Suspension Bridge with

1711-552: The River Paiva, Arouca Geopark , Portugal, opened in April 2021. The 516 metres bridge hangs 175 meters above the river. Where such a bridge spans a gap between two buildings, there is no need to construct towers, as the buildings can anchor the cables. Cable suspension may also be augmented by the inherent stiffness of a structure that has much in common with a tubular bridge . Typical suspension bridges are constructed using

1770-432: The bridge deck. Before the deck is installed, the cables are under tension from their own weight. Along the main cables smaller cables or rods connect to the bridge deck, which is lifted in sections. As this is done, the tension in the cables increases, as it does with the live load of traffic crossing the bridge. The tension on the main cables is transferred to the ground at the anchorages and by downwards compression on

1829-492: The bridge to be closed on 12 June for modifications. Attempts had been made to limit the number of people crossing the bridge, which led to long queues but were ineffective to dampen the vibrations. Closure of the bridge only two days after opening attracted public criticism as another high-profile British Millennium project that suffered an embarrassing setback, akin to how many saw the Millennium Dome . The vibration

Millennium Bridge, London - Misplaced Pages Continue

1888-473: The bridge, the vibrational modes had not been anticipated by the designers. When the bridge lurches to one side, the pedestrians must adjust to keep from falling over, and they all do this at the same time. The effect is similar to soldiers marching in lockstep, but horizontal instead of vertical. The risks of lateral vibration in lightweight bridges are well known. Any bridge with lateral frequency modes of less than 1.3 Hz, and sufficiently low mass, could witness

1947-491: The chains are not attached to abutments as is usual, but instead are attached to the main girders, which are thus in compression. Here, the chains are made from flat wrought iron plates, eight inches (203 mm) wide by an inch and a half (38 mm) thick, rivetted together. The first wire-cable suspension bridge was the Spider Bridge at Falls of Schuylkill (1816), a modest and temporary footbridge built following

2006-631: The collapse of James Finley's nearby Chain Bridge at Falls of Schuylkill (1808). The footbridge's span was 124 m, although its deck was only 0.45 m wide. Development of wire-cable suspension bridges dates to the temporary simple suspension bridge at Annonay built by Marc Seguin and his brothers in 1822. It spanned only 18 m. The first permanent wire cable suspension bridge was Guillaume Henri Dufour 's Saint Antoine Bridge in Geneva of 1823, with two 40 m spans. The first with cables assembled in mid-air in

2065-529: The collapse was largely caused by the construction failure of the vertical hanging clamp. It was also found that poor maintenance, fatigue in the cable hanger construction materials, material quality, and bridge loads that exceed vehicle capacity, can also have an impact on bridge collapse. In 2013 the Kutai Kartanegara Bridge rebuilt the same location and completed in 2015 with a Through arch bridge design. On 30 October 2022, Jhulto Pul ,

2124-522: The collapse; several drivers escaped their cars on foot and reached the anchorages before the span dropped. Yarmouth suspension bridge (England) was built in 1829 and collapsed in 1845, killing 79 people. Peace River Suspension Bridge (Canada), which was completed in 1943, collapsed when the north anchor's soil support for the suspension bridge failed in October 1957. The entire bridge subsequently collapsed. Kutai Kartanegara Bridge (Indonesia) over

2183-479: The deck panels – to control lateral movement, 4 vertical to ground dampers to control lateral and vertical movements, and 16 pier dampers to control lateral and torsional movements. Additionally, 52 tuned mass dampers add inertia to control vertical movement. The work took from May 2001 to January 2002 and cost £5 million. After a period of testing, the bridge was reopened on 22 February 2002 and, since that date, has not been subject to significant vibration. In spite of

2242-435: The effect; the maximum sway was around 70 millimetres (2.8 in). On the day of opening, the bridge was crossed by 90,000 people, with up to 2,000 on the bridge at a time. Resonant vibrational modes due to vertical loads (such as trains, traffic or pedestrians) and wind loads are well understood in bridge design. In the case of the Millennium Bridge, because the lateral motion caused pedestrians to directly participate with

2301-584: The failure of a few flawed strands in the hundreds used pose very little threat of failure, whereas a single bad link or eyebar can cause failure of an entire bridge. (The failure of a single eyebar was found to be the cause of the collapse of the Silver Bridge over the Ohio River .) Another reason is that as spans increased, engineers were unable to lift larger chains into position, whereas wire strand cables can be formulated one by one in mid-air from

2360-432: The highway, which may be supported by suspender cables or their own trusswork . In cases where trusswork supports the spans, there will be very little arc in the outboard main cables. The earliest suspension bridges were ropes slung across a chasm, with a deck possibly at the same level or hung below the ropes such that the rope had a catenary shape. The Tibetan siddha and bridge-builder Thangtong Gyalpo originated

2419-534: The live loads. In an underspanned suspension bridge, also called under-deck cable-stayed bridge, the main cables hang entirely below the bridge deck, but are still anchored into the ground in a similar way to the conventional type. Very few bridges of this nature have been built, as the deck is inherently less stable than when suspended below the cables. Examples include the Pont des Bergues of 1834 designed by Guillaume Henri Dufour ; James Smith's Micklewood Bridge; and

Millennium Bridge, London - Misplaced Pages Continue

2478-702: The modern method was Joseph Chaley 's Grand Pont Suspendu in Fribourg , in 1834. In the United States, the first major wire-cable suspension bridge was the Wire Bridge at Fairmount in Philadelphia, Pennsylvania. Designed by Charles Ellet Jr. and completed in 1842, it had a span of 109 m. Ellet's Niagara Falls suspension bridge (1847–48) was abandoned before completion. It was used as scaffolding for John A. Roebling 's double decker railroad and carriage bridge (1855). The Otto Beit Bridge (1938–1939)

2537-406: The pillars to deck-level supports, and further continue to connections with anchors in the ground. The roadway is supported by vertical suspender cables or rods, called hangers. In some circumstances, the towers may sit on a bluff or canyon edge where the road may proceed directly to the main span. Otherwise, the bridge will typically have two smaller spans, running between either pair of pillars and

2596-413: The railing and the walking layer of Gyalpo's bridges used wires. The stress points that carried the screed were reinforced by the iron chains. Before the use of iron chains it is thought that Gyalpo used ropes from twisted willows or yak skins. He may have also used tightly bound cloth. The Inca used rope bridges , documented as early as 1615. It is not known when they were first made. Queshuachaca

2655-612: The roadbed, particularly owing to the unfavorable effects of using plate girders, discovered from the Tacoma Narrows Bridge (1940) bridge collapse. In the 1960s, developments in bridge aerodynamics allowed the re-introduction of plate structures as shallow box girders , first seen on the Severn bridge , built 1961–1966. In the picture of the Yichang Bridge , note the very sharp entry edge and sloping undergirders in

2714-420: The same phenomenon with sufficient pedestrian loading. The greater the number of people, the greater the amplitude of the vibrations. Other bridges which have seen similar problems are: Engineers at Arup , the company that designed the bridge, conducted research into the unexpected oscillation, which they called 'synchronous lateral excitation'. The first laboratory studies used pedestrians on moving platforms at

2773-650: The signals from those transducers were amplified and dynamically distributed throughout the Turbine Hall of the Tate by a programme which Fontana entered into the sound diffusion engine of the Richmond Sound Design AudioBox. In October 2023, the bridge was closed for three weeks to allow repairs to its surface, undertaken by FM Conway . The bridge closed on Saturday 14 October and reopened late on 5 November. A short inclined lift , known as

2832-410: The soldiers march in their relatively elevated pace. The United States march command is "For-ward, MARCH," or "quick time, MARCH" when resuming quick time from another pace or from "route step". Arm movement is kept to 9 inches to the front and 6 inches to the rear (6 inches and 3 inches, respectively, in the U.S. Navy, Coast Guard, Marine Corps, and Air Force) while marching, while

2891-467: The successful cure, the "wobbly bridge" (sometimes "wibbly-wobbly") epithet remains in common usage among Londoners. An artistic expression of the higher-frequency resonances within the cables of the bridge were explored by Bill Fontana's Harmonic Bridge exhibition at the Tate Modern in mid-2006. This used acoustic transducers placed at strategic locations on the cabling of the Millennium Bridge and

2950-401: The suspension bridge shown. This enables this type of construction to be used without the danger of vortex shedding and consequent aeroelastic effects, such as those that destroyed the original Tacoma Narrows bridge. Three kinds of forces operate on any bridge: the dead load, the live load, and the dynamic load. Dead load refers to the weight of the bridge itself. Like any other structure,

3009-514: The ten bridges with the longest spans, followed by the length of the span and the year the bridge opened for traffic: (Chronological) Broughton Suspension Bridge (England) was an iron chain bridge built in 1826. One of Europe's first suspension bridges, it collapsed in 1831 due to mechanical resonance induced by troops marching in step. As a result of the incident, the British Army issued an order that troops should "break step" when crossing

SECTION 50

#1732802168516

3068-532: The terrace which is level with the deck of the bridge. It was primarily installed for use by those who cannot easily manage the steep steps, such as people with disabilities and parents with push chairs . The lift carriage was originally powered by an electric traction motor , manufactured in Italy by Maspero Elevatori, with a speed of 0.5 metres per second (1.6 ft/s) and a maximum capacity of 0.7 metric tons (0.77 short tons ; 0.69 long tons ). However, by 2010

3127-489: The towers. In cable-stayed bridges, the towers are the primary load-bearing structures that transmit the bridge loads to the ground. A cantilever approach is often used to support the bridge deck near the towers, but lengths further from them are supported by cables running directly to the towers. By design, all static horizontal forces of the cable-stayed bridge are balanced so that the supporting towers do not tend to tilt or slide and so must only resist horizontal forces from

3186-568: The use of iron chains in his version of simple suspension bridges . In 1433, Gyalpo built eight bridges in eastern Bhutan . The last surviving chain-linked bridge of Gyalpo's was the Thangtong Gyalpo Bridge in Duksum en route to Trashi Yangtse , which was finally washed away in 2004. Gyalpo's iron chain bridges did not include a suspended-deck bridge , which is the standard on all modern suspension bridges today. Instead, both

3245-423: The weight of the cables is small compared to the weight of the deck. One can see the shape from the constant increase of the gradient of the cable with linear (deck) distance, this increase in gradient at each connection with the deck providing a net upward support force. Combined with the relatively simple constraints placed upon the actual deck, that makes the suspension bridge much simpler to design and analyze than

3304-435: Was an innovative "blade of light" effort from Arup Group , Foster + Partners and Anthony Caro . Due to height restrictions , and to improve the view, the bridge's suspension design had the supporting cables below the deck level, giving a very shallow profile. The bridge has two river piers and consists of three main sections of 81 m (266 ft), 144 m (472 ft), , 108 m (354 ft) (north to south) with

3363-412: Was attributed to a then-underresearched phenomenon whereby pedestrians crossing a bridge that has a lateral sway have an unconscious tendency to match their footsteps to the sway, exacerbating it. This is different from the well-understood problem of vertical sway, which is why troops stop marching in stride together as a unit when crossing such a bridge. An example is London's Albert Bridge , which has

3422-661: Was built between 1829 and 1832, replacing a wooden bridge further downstream which collapsed in 1828. It is the only suspension bridge across the non-tidal Thames. The Széchenyi Chain Bridge , (designed in 1840, opened in 1849), spanning the River Danube in Budapest, was also designed by William Clark and it is a larger-scale version of Marlow Bridge. An interesting variation is Thornewill and Warham 's Ferry Bridge in Burton-on-Trent , Staffordshire (1889), where

3481-404: Was the first modern suspension bridge outside the United States built with parallel wire cables. Two towers/pillars, two suspension cables, four suspension cable anchors, multiple suspender cables, the bridge deck. The main cables of a suspension bridge will form a catenary when hanging under their own weight only. When supporting the deck, the cables will instead form a parabola , assuming

#515484