Britannia Bridge

'' 1852. The opening of the Menai Bridge in 1826, to the east of where Britannia Bridge was later built, provided the first fixed road link between Anglesey and the mainland. The increasing popularity of rail travel shortly necessitated a second bridge to provide a direct rail link between London and the port of Holyhead, the Chester and Holyhead Railway. Other railway schemes were proposed, including one in 1838 to cross Thomas Telford's existing Menai Bridge. Railway pioneer George Stephenson was invited to comment on this proposal but stated his concern about re-using a single carriageway of the suspension bridge, as bridges of this type were unsuited to locomotive use. By 1840, a Treasury committee decided broadly in favour of Stephenson's proposals, however, final consent to the route, including Britannia Bridge, would not be granted until 30 June 1845, the date on which the corresponding Parliamentary Bill received royal assent. supported by masonry piers, the centre one of which was to be built on the Britannia Rock. Two additional spans of length would complete the bridge, making a continuous girder. The trains were to run inside the tubes (inside the box girders). Up until then, the longest wrought iron span had been , barely one fifteenth of the bridge's spans of . As originally envisaged by Stephenson, the tubular construction would give a structure sufficiently stiff to support the heavy loading associated with trains, but the tubes would not be fully self-supporting, some of their weight having to be taken by suspension chains. It became apparent from Fairbairn's experiments that- without special precautions - the failure mode for the tube under load would be buckling of the top plate in compression, the theoretical analysis of which gave Hodgkinson some difficulty. When Stephenson reported to the directors of the railway in February 1846, he attached reports by both Hodgkinson and Fairbairn. From his analysis of the resistance to buckling of tubes with single top plates, Hodgkinson believed that it would require an impracticably thick (and therefore heavy) top plate to make the tubes stiff enough to support their own weight, and advised auxiliary suspension from link chains. == Construction and use ==

On 10 April 1846, the foundation stone for the Britannia Bridge was laid, marking the official commencement of construction work at the site. However, this station was closed after only years in operation owing to low passenger volumes. In the present day, little remains of this station, other than the remnants of the lower-level station building. A new station named Menai Bridge was opened shortly afterwards. Lions The bridge was decorated by four large lions sculpted in limestone by John Thomas, two at either end. == Fire and reconstruction ==

During the evening of 23 May 1970, the bridge was heavily damaged when boys playing inside the structure dropped a burning torch, setting alight the tar-coated wooden roof of the tubes. Despite the best efforts of the Caernarfonshire and Anglesey fire brigades, the bridge's height, construction, and the lack of an adequate water supply meant they were unable to control the fire, which spread all the way across from the mainland to the Anglesey side. carrying a single-carriageway section of the A5 road (now the A55). During 2011, national railway infrastructure owner Network Rail, the Welsh Assembly Government and the Highways Agency undertook a £4 million joint programme to strengthen the then 160-year-old structure and improve its reliability. == Proposed bridge improvement ==

(seated centre) with the engineers who designed and built the Britannia Bridge. In November 2007, a public consultation exercise into the ‘A55 Britannia Bridge Improvement’ commenced. The perceived problems stated include: • It is the only non-dual-carriageway section along the A55 • Congestion during morning and afternoon peak periods • Congestion from seasonal and ferry traffic from Holyhead • Queuing at the junctions at either end • Traffic is expected to significantly increase over the next ten years or so In the document, four options are presented, each with their own pros and cons: • Do nothing. Congestion will increase as traffic levels increase. • Widen existing bridge. To do this, the towers would have to be removed to make room for the extra lanes. This is an issue as the bridge is a Grade II listed structure and is owned by Network Rail. The extra lanes would have to be of reduced width as the existing structure is not capable of supporting four full-width lanes. • New multi-span concrete box bridge alongside. Building a separate bridge would allow the existing bridge to be used as normal during construction. The bridge would require support pillar(s) in the Menai Strait, which is an environmental issue as the strait is a Special Area of Conservation. Visual impact would be low as the pillars and road surface would be aligned with the current bridge. • New single span cable-stayed bridge. This would eliminate the need for pillars in the Strait, but the bridge would have a large impact on the landscape due to the height of the cable support pillars. This is also the most costly option. Respondents were overwhelmingly in favour of seeing some improvements, with 70 per cent favouring the solution of building another bridge. == Similar bridges ==

Very few other tubular iron bridges were ever built since more economical bridge designs were soon developed. The most notable of the other tubular bridges were Stephenson's Conwy Railway Bridge between Llandudno Junction and Conwy, the first Sainte-Anne-de-Bellevue (Québec) Grand Trunk Railway bridge, which was the prototype of the Victoria Bridge across the Saint Lawrence River at Montreal. The Conwy railway bridge remains in use, and is the only remaining tubular bridge; however, intermediate piers have been added to strengthen it. The bridge can be seen at close quarters from Thomas Telford's adjacent 1826 Conwy Suspension Bridge. The Victoria Bridge was the first bridge to cross the St. Lawrence River, and was the longest bridge in the world when it was completed in 1859. It was rebuilt as a truss bridge in 1898. ==See also==