031A - Britannia Bridge

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In Folder: Historical Engineering Collection

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031A - Britannia Bridge

Proposed as a railway through North Wales, connecting London via Chester with the Port of Holyhead in Anglesey, the Chester and Holyhead Railway Act was passed in June 1845. Robert Stephenson was soon appointed its chief engineer. By 1848 construction of the railway had been finished between Chester and Bangor and Llanfair PG and Holyhead. The bridge that would take the railway over the Menai Strait would make the line complete. The bridge was to link the mainland just west of Bangor to the island of Anglesey, making use of the Britannia Rock midstream. As the Menai Strait was still a navigable channel towards the Irish Sea, the Admiralty stipulated that any bridge crossing it should pose no obstruction to shipping during construction, and must have headroom of 105ft (31.5m) above high water level. Robert Stephenson proposed a tubular type of bridge; the railway line running through tubes made up of wrought iron riveted plates. The bridge consisted of two main spans of 460ft and two smaller spans at each side of 230ft, all supported by masonry towers, the tallest being the Britannia Tower at 221ft. In this design, Stephenson was assisted by three men, William Fairburn (in designing the distinctive ‘tubes’ through which the trains originally ran), Eaton Hodgkinson (who investigated the strength of the tubular structure) and Edwin Clark (Stephenson’s resident engineer). The two longest tubes were built in sections on the Caernarfon shore, and were floated into position using pontoons then raised onto the towers using a hydraulic jack. Once in position they were joined inside the tower making a continuous beam of 1511ft – at the time the longest wrought iron span in the world. On the wing walls at the end of each abutment tower, two grand lions, sculpted by John Thomas, kept watch. Both lines on the bridge were opened to traffic on 19 October 1850. The Britannia Bridge remained unaltered, other than routine maintenance until a disastrous fire took hold in the tubes on 23 May 1970. Heat from the fire was so intense that the central tubes buckled and had to be dismantled. A new, open lattice steel arch bridge was designed by Husband & Co of Darlington which made use of Stephenson’s masonry towers. The bridge reopened for rail traffic in 1972. By the mid 1970s as road traffic using the A5 over Thomas Telford’s road bridge across the Menai Straits was increasing, the decision was taken to transform the Britannia Bridge into a combined road and rail bridge. Construction of the road deck to the bridge started in October 1977 and opened to road traffic in 1980.

Network Rail Corporate Archive

Level of Description: Series

Reference Code: NRCA11046-NRCA170041

Title: Britannia Bridge

Extent and Medium: 38 Drawings

Creator: Chester and Holyhead Railway

Date: 1846-1848

Scope and Content: 38 drawings from the Britannia Bridge Contract showing the designs for the bridge by the Chester and Holyhead Railway Company. Designed by Robert Stephenson.

Contract Number: Britannia Bridge

Drawing Number: n/a

Drawing Office Number: n/a

Keywords (Person): Stephenson, Robert

Keywords (Country): Wales

Keywords (Structure Name): Britannia Bridge

Keywords (Structure Type): Bridge or Viaduct

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Title

Description

Date

Chester and Holyhead Railway – Britannia Bridge Contract – Sketch of Inscription for Frieze of Abutment Tower Caernarvon Side [Part 2]

1 drawing on 2 sheets. Working drawing for the Britannia Bridge showing elevation of inscription of the Frieze on the Abutment Tower Carnarvon side. Inscription reads "ERECTED ANNO DOMINI MDCCCXLIX ROBERT STEPHENSON ENGINEER"

[1846-1848]

Section of Menai Straits Britannia Rock

Section of the Menai Straight, with gorund levels, and various water levels

1848

Chester and Holyhead Railway – Britannia Bridge Contract Drawing No.8 – End Towers at Entrance of Tunnel on Caernarvon Side

Three drawings on one sheet. Drawing No. 8 for Contract No. 10 Britannia Bridge. First drawing is of end towers at entrance of tunnel on Caernarvon side, second drawing is of front elevation, third drawing is of longitudinal section. This is the drawing No. 8 as referred to in the "Contract No. 10 Britannia Bridge Contract" the day made and entered into by us with the Chester and Holyhead Railway Company. Signed by Benjamin [T] Nowell, John Hemingway, J B Hemingway and Charles Pearson

May 1846

Chester and Holyhead Railway – Britannia Bridge Contract Working Drawings – Side Elevation and Wing Wall of Abutment Tower Anglesea Side

2 drawings on 1 sheet. Working drawing of the Britannia Bridge showing elevation next to tube and side elevation and winged wall

February 1848

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