Pont Britannia

The Pont Britannia ( Britannia Bridge ) is one of the two bridges which connect the island of Ynys My or Anglesey, to the dry land of the Wales, vis-a-vis Bangor, above the Menai, or strait of Carried out.

In the beginning, it was an only railway tubular bridge, composed of spans in rectangular beams closed out of wrought iron, built in 1850 by Robert Stephenson. Currently, and since the years 1970, it is an arch bridge rail-road, out of steel, on two levels.

The bridge of Robert Stephenson

An uncommon range

A first road bond between Anglesey and the dry land had already established in 1826 by the suspended bridge of the strait of Carried out. However, the growing popularity of the railway journeys well quickly required a second bridge intended to establish a bond of direct rail between London and the port of Holyhead.

It is with Robert Stephenson, wire of the pioneer of the railroads George Stephenson, which was entrusted the task to build such a bridge, with one thousand (1.6 km) in the east of the existing suspended bridge. Constrained by the fact that the strait was to remain accessible to the sea traffic, and that the new railway bridge was to be sufficiently rigid to support the weight of the trains, it built a bridge with two principal ranges of 460 feet (140 m), consisted of long iron tubes of rectangular section, each one of them weighing up to 1500 tons. See historical Anglesey and its bridges

These metal spans were supported by piles in masonry, the central pile resting directly on the Britannia small island. Two spans of access, each one long of 230 feet (70 m), supplemented the bridge, thus forming a continuous beam a length of 1511 feet (461 m). Hitherto, the greatest range of a wrought iron bridge had been of 31 feet 6 inches (9,6 m).

Should an auxiliary suspension be envisaged?

Stephenson took for advisers two eminent engineers: William Fairbairn, an old friend of his father, and Eaton Hodgkinson, large specialist in the Resistance of the materials. Hodgkinson found unrealistic to want to be satisfied with Tube S, and advised a suspension with chain S, at least in complement. On the contrary, Fairbairn thought that the chains were not necessary: " If all is well calculated and the correctly riveted plates, he said, you can arrange your chains and to have a monument perfectly usable, perfect witness of knowledge and techniques of his time! "

Bond: Robert Stephenson and his team, in conference in front of the Britannia bridge

Iron tubes hoisted towards the sky

The majority opinion leant rather for the positions of Hodgkinson, but Stephenson supported, with a certain nervousness, the opinion of Fairbairn. To have the heart Net of it, one decided to build and test on the shipyard of Fairbairn, in Millwall (on the Thames, close to London), a model of 75 feet (25 m) of range, intended to be used as a basis for the final project.

Started in 1846, the bridge was open on March 5th, 1850. For its time, it was a building of an uncommon size, and a singular innovation, its considerable range leaving far behind him the contemporary bridges in cast iron beams or sheet plates. Innovating, it was it also in its method of construction: the elements of the wrought iron tube were assembled with ground, then put on barges before being hoisted in their final position.

The completed work, one could decorate the bridge with four large lions of style victorien, carved by John Thomas, with each angle.

Since this time, and in spite of the convoys increasingly heavier than it had to support in the decades which followed, the Britannia bridge was always regarded as every success of the engineer Robert Stephenson, which had also to build in same time the High Level Bridge, with the Newcastle-upon-Tyne and the tubular bridge of Conwy, Wales, just beside the suspended bridge with chains of Thomas Telford (1826). One century and half after their construction, all these bridges are always in service!

Set fire to and rebuilding

Malicious kids

Original the Britannia bridge would be him also certainly quite alive, so of the imprudent kids had not undertaken, the evening of May 29th, 1970, to nuitamment visit nuitamment the iron tube in lighting of torches. One of them escaped to them, and fire took in all the tube, which one warned oneself that it was reinforced in its hollow parts by sawn timber beams, which did not finish any burning, slowly but surely, and that nobody managed to extinguish.

Official report on the fire
Photographs of the board of inquiry after the fire
BBC News: video of the fire

In the days which followed, it was necessary to go obviously: the bridge, although apparently intact considering by far, partly was destroyed, deformed by heat, and had lost any resistance. It was thus necessary to be solved to entirely dismount it and to reconsider it.

The high piles, whose strange silhouette égyptianisante guard always the mark of the first tubular project of bridge reinforced with an auxiliary suspension with chains, remained in perfect state. One decided thus to re-use them, and when one had increased the passages which cross them in their top, one was given for task, not to rebuild the work such as it was before, but to adapt it to the modern needs.

The bridge today

Thus Britannia Bridge took the aspect that one knows to him today: a steel arch bridge of two levels, one, lower, intended for the rail traffic, the other, in " mezzanine" , supporting an intense road traffic, and even highway.

The inhabitants of Anglesey, who were hitherto to be satisfied with the old suspended bridge of Telford for their road bonds with the dry land, thus have today a fast and modern connection, happy and unexpected, consecutive solution with an annoying accident.

See too

Bridge Victoria (Montreal)

External bonds

Britannia Bridge, on Structurae
Very beautiful images
Science & Society, Picture Library: 500 images concerning Stephenson.
Anglesey and its bridges: detailed history
Prosiect Carried out: Project of museum and arts center on the topic of the strait of Carried out.

Random links: