Pont du Forth

Located at 14 kilometers in the west of the Scottish city of Edinburgh, the bridge of Forth is the second longer bridge of the type Cantilever in the world as for its free range (the first being the Pont of Quebec) and the first of big size ever built. Its length is higher than 2,5 kilometers. It is only intended for the rail traffic and makes it possible to connect the Council area of Edinburgh to that of Fife and Kinross by spanning the river Forth. It thus constitutes a major axis of transport between the North-East and the south-east of the country, doubled since 1964 by the highway Pont of Forth. It is registered since 1999 on the indicative list of the world heritage of UNESCO.

Geographical location

The bridge is located at 14 kilometers in the west of Edinburgh, on the east coast of the Scotland, in the north of the the United Kingdom. It crosses the Fleuve Forth, which cuts Scotland of west in is, between the town of Queensferry ( Council area of Edinburgh) on southern bank and that of North Queensferry ( council area of Fife) on northern bank, with the entry of the Estuaire of the Firth off Forth. In this place, the river undergoes a contracting allowing this construction, this in spite of a very important depth (between 60 and 65 meters) which is higher than that of the the North Sea on which the estuary gives. That thus explains the need that there was to build a bridge with a limited number of spans, the technology of the time not allowing the easy construction of piles such a depth.

History

Before the bridge

As from the 12th century, a ferry is set up between Queensferry, and the port of North Queensferry, which uses as quays of the natural headlands. Towards 1760 it acts of the ferry more attended the United Kingdom, but it is regarded by the users as being “slow, uncomfortable and dangerous”. Also, towards 1805, a project of tunnel of Sir Thomas Bouch is seriously studied but finally abandoned because of its price estimated at more: 160000 £ . One thus decides in 1808 to modernize the system of ferry under the direction of the engineer John Rennie who in particular makes build piers allowing the loading whatever the tide, and thus increases the connections.

However, the development of transport, and in particular the rise of the Railroad, quickly make necessary the construction of a bridge. The system of transshipment of the trains by ferry, set up in 1805 between Granton and Burntisland, becomes indeed very quickly insufficient.

Various projects

In 1818, a first project of suspended bridge is thus presented by James Anderson but immediately abandoned because of the lightness of the structure which makes fear an immediate collapse. One says even in 1890 which the structure of the bridge would have been “so fine that it would have been hardly visible in gloomy weather, and that after a strong strong gale one would have seen it more, not even by day of good weather”.

They are only fifty-five years later that the Forth Bridge Railway Company is created, company of railroad of which the goal is to build a bridge so that the trains of the East Coast Railway Companies are not obliged any more to use the lines of their competitor Caledonian Railway . It chooses then the project of Suspended bridge of Sir Thomas Bouch, which was approved by a commission of engineers. But work does not start immediately because the company North British which belongs to the same group, is then building the Pont of Tay, also drawn by Bouch, and of this fact does not have the liquidities necessary. The first stone thus is finally posed in spring 1879 with Inchgarvie. But, on December 28th 1879, the bridge of Tay collapses, carried by a hurricane, which causes the death of seventy-five people. The charged commission of the investigation then allots the catastrophe to a too great brittleness of the apron due to a bad calculation of its originator, Thomas Bouch. Work of the bridge of Forth thus is immediately stopped by fear of a similar awkwardness.

The construction of the current bridge

Following the stop of the construction of the project of Bouch, Forth Bridge Railway Company brings together its engineers in 1880 to establish new plans. At the end of one year, in May 1881 Fowler and Baker present the plans of a bridge of the type Cantilever, extremely robust and especially conceived to resist the winds more the violent ones because the catastrophe of the bridge of Tay remain in all the memories. After having received the approval of the company, those are subjected to the Parlement which grants the official authorization in July 1882. Work thus starts with the construction of the three boxes intended to support the cantilevers. At the end of five years, in 1887, the three arms cantilever are built and in place. It thus remains to connect them, delicate operation which then takes a rather long time because of the bad climatic conditions. But finally, on March 4th 1890, two trains long of more than 300 meters and weighing each one nearly 900 tons, composed of an engine drawing fifty coaches, side-by-side cross the bridge south towards north.

To arrive at this result, it will have been necessary more: 58000 tons of Steel, 6,5 million Rivet S: 20950 cubic meters of Granite: 49200 cubic meters of Broken stones and: 21350 tons of Cement. Four thousand men will have worked on this work during nearly eight years, and fifty-seven will have died about it in spite of the security measures installation. The whole at a cost of 3,2 million books of the time, which is equivalent to approximately 235 million 2000 is 347 million euros.

The inauguration

March 4th 1890 the prince de Galles fixes the last rivet, cast out of gold for the occasion, inaugurating thus solemnly the work in the presence of his/her son, the future king George V, of the duke of Edinburgh, many deputies as well as representatives of foreign companies of railroad. Among the latter appear in particular Gustave Eiffel and Frederic Fromhold Martens.

At the time it becomes the bridge the longest cantilever in the world and mark a turning in the history of the construction of works out of steel.

Characteristics

This bridge, which measures on the whole 2528 Mètre S, is actually an assembly of two bridges end to end put cantilever. It consists of fifteen small arches of 51 meters each one (ten in the south and five in north), of two side arches of 207 m, and the two principal arches of a unit range of 521 meters. Each principal arch is made up of two arms in Porte-à-faux of 207 m which support the central beam of the bridge (106 m), placed at 46 m above water with high tide. The three turns which support the cantilever have a 104 m height and rest on deep boxes of 27 m, partly built thanks to Compressed air.

The use of a structure cantilever did not constitute an innovation, but size of the work of Baker and calculations that it carried out as a preliminary, of which in particular those on the blast pressure or the influence of the temperature on the rigidity of the bridge, were on the other hand signification advances in the field of construction which allowed the realization of other structures of similar design in the whole world, of which the Pont of Quebec.

Rail traffic

In 2000, the bridge saw passing: 54080 passenger trains and 6240 goods trains representing a total load higher than 10,5 million ton S. These figures are to be compared with those 1894 which were of: 26451 momentary trains and: 18777 goods trains for nearly 7,5 million transported tons.

On average, it is thus nearly 150 to 200 trains which borrow this bridge each day, whatever the time. Since 1930, the bridge was indeed closed only with four recoveries for one weekend during the year 2003 to facilitate work of painting.

Maintenance

Although the modern trains subject the bridge to less of efforts than the first steam trains, this one requires a constant maintenance nevertheless. “To paint the bridge of Forth” even in Great Britain an expression became indicating a task without end, version modern of the myth of Sisyphus. It rests on a legend which wants that as soon as the team charged to repaint the bridge reaches an end, it is necessary to start again other side. That is explained by the immense surface of the metal beams which represent close to: 20000 square meters.

In 1996, Railtrack, the operating company the work, undertake a program of great width intended to restore the whole of the structure. Forty million books is thus invested in work which starts in 1998, including/understanding the change of certain damaged beams, the painting of the whole of the work, an improvement of the access and a new lighting. But in 2002 a new invitation to tender is launched, following the withdrawal of the preceding contractor who cannot complete his work because of bad climatic conditions and of financial problems. It is gained by the second company of civil engineering of the country, Balfour Beatty, which signs a contract of ten million books per annum until in 2009, for the maintenance of the bridge. It in particular will sand all the metal parts to remove the preceding coats of paint, to apply a first layer containing Zinc thickness a 35 microns to avoid any corrosion, then one second made up of " glassflake" of epoxy intended to form a barrier of 400 microns, and finally a varnish of Polyurethane to give again with the bridge the famous red which contributes to its charm. The whole thus represents a surface of: 400000 m ² to be painted, which is guaranteed for one twenty years duration.

The width of these maintenance costs led a Labor deputy, Helen Eadie, to require in 2003 the demolition of this bridge.

Memorial

During more than one hundred years, the number of workmen who found death by building the bridge was fixed at 57. However in 2004, a study based on the death certificates established that there had actually been 63 victims, for which no memorial did not exist. March 12th, 2005, a committee is thus made on the initiative of the deputy John Barrett with for goal to list all these deaths and to pay homage to them. For this purpose, several projects of monuments are under study.

Symbol

The bridge of Forth has a strong value symbolic system for the Scot because it connects the north and the south of Scotland while crossing Forth which separates them. Moreover, he testifies by his character to pioneer a certain Scottish technical know-how and thus makes forget the failure which the catastrophe of the bridge of Tay had constituted. He also reflects a certain golden age of the Scottish economy, which suffered much during the 20th century.

This bridge, which was bombarded by the Luftwaffe during the Second world war without never being reached in spite of fakings of the photographs of propaganda, thus constitutes the symbol of Scotland always upright in the middle of the difficulties, and connects its past to the future according to Alex Salmond, chief of the Parti national Scot.

He would be even regarded by the Scot as the eighth wonder of the world according to Roland Paxton, professor at the University Heriot-Watt of Edinburgh.

Anecdotes

the bridge is put in scene by Alfred Hitchcock in his film of 1935 the 39 steps , and in the remake of 1959.
the bridge of Kincaid in the video game Grand Theft Auto: San Andreas is inspired by this bridge, Rockstar North which produces it being based in Edinburgh.
the bridge was reproduced a long time on the advertizing posters for soda Irn-Daughter-in-law, with the slogan “Made in Scotland, from girders” (“Manufactured in Scotland, starting from beams”).
the architecture of the bridge was not always admired. Thus the artist and poet William Morris declared at the time of the inauguration that this bridge was a “supreme specimen of the ugliness”.
the part of a Pound sterling left in 2004 represents the bridge of Forth.
“Painting the Forth Bridge” (“To paint the bridge of Forth”) is an English expression indicating a task without end. (See explanation)
In 1996, during the renovation work of the bridge, thousand rivets of origin was sold like clipboard with the price of 30£ part. Since 2006, other rivets are on sale on the site of Forth Bridges Visitors Center Trust, association for the promotion of this monument.
In 2003, Sebastien Foucan , a French founder of the Free running and cofounder of the Parkour, are filmed running without harness on the highest beams of the bridge of Forth for Jump Britain , documentary diffused on Chanel 4.

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