Bridges and viaducts › Britannia Bridge

Britannia Bridge

Stephenson's bridge across the Menai Strait, opened in 1850 as iron tubes and rebuilt after the 1970 fire as a steel arch bridge with a road deck above the railway: two main spans of 460 ft (140 m), on towers up to 221 ft (67 m) tall.

Opened
1850; rebuilt after the 1970 fire (rail deck 1972, A55 road deck 1980)
Line
North Wales Coast Line (Chester to Holyhead), with the A55 above
Kind
Steel arches on the original masonry towers
Spans
Two of 460 ft (140 m) and two of 230 ft (70 m)
Towers
The Britannia Tower is 221 ft (67 m) tall
Clearance
103 ft (31 m) under the rail deck at high water
Lions
Four limestone lions, each 25 ft (7.6 m) long and 12 ft (3.7 m) high
Train drawn
Avanti West Coast Class 805

unverified Some of these figures haven’t yet been checked against an official source or a published history. What’s in doubt ↓

Britannia Bridge, schematic side elevation at 1 px a metre, with an Avanti West Coast Class 805 crossing
An Avanti West Coast Class 805 crossing. Schematic side elevation at 1 px a metre, a tenth of the scale of the train drawings: proportions from the published figures, details simplified.

Four times larger

Britannia Bridge, schematic side elevation at 4 px a metre, with an Avanti West Coast Class 805 crossing
An Avanti West Coast Class 805 crossing. Schematic side elevation at 4 px a metre: proportions from the published figures, details simplified. Scroll sideways to see it all.

Close up

At 10 px a metre, the scale of the train drawings, so the train is the size it is on its own page. Each is cut from the same drawing.

Britannia Bridge, close-up: The Anglesey abutment tower, with the plinth of a lion beside it.
The Anglesey abutment tower, with the plinth of a lion beside it.
Britannia Bridge, close-up: The Britannia Tower on its rock, an arch springing from each side.
The Britannia Tower on its rock, an arch springing from each side.
Britannia Bridge, close-up: An Avanti West Coast Class 805 between the two ribs, under the road deck.
An Avanti West Coast Class 805 between the two ribs, under the road deck.

Sources

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Show the 11 sources from Wikimedia Commons, Edwin Clark and Robert Stephenson, Cadw and 5 more
  • General Description of the Britannia and Conway Tubular Bridges on the Chester and Holyhead Railway Edwin Clark and Robert Stephenson, 1849, pp. 9-12, 14-15two main spans, the side (land) towers 460 ft clear from the centre tower and the abutments 230 ft inland of them; the Britannia Tower 62 ft by 52 ft 5 in at the base, 55 ft by 45 ft 5 in where the tubes enter, nearly 230 ft from the foundations; the land towers 62 by 52 ft 5 in at the base, 55 by 32 ft at the tubes' level, 190 ft from high water; the strait about 1,100 ft wide at high water, the Britannia Rock covered 10 ft at high water, tide range 20 ft; the tubes 30 ft high at the centre; the lions 25 ft long and 12 ft high, 11 pieces of limestone, John Thomas
  • Britannia Bridge: listed building full reports 3674 (Pentir) and 5488 (Llanfair Pwllgwyngyll), Grade II Cadw, read 9 November 2026the tubes 102 ft (31 m) over high water; 459 ft 3 in (140 m) between the intermediate water piers; the two central water piers 221 ft 3 in (67.5 m) from the foundation; the modified bridge: braced riveted steel section arches with N-truss spandrels between the earlier piers, the road carried on stanchions above the railway, the side spans in reinforced concrete; the lions on high plinths; Husband & Co for British Railways, the Cleveland Bridge & Engineering Co as contractors
  • The history of the Britannia Bridge, North Wales Network Rail, read 9 November 2026two main spans of 460 ft and two smaller of 230 ft on masonry towers, the tallest the Britannia Tower at 221 ft; headroom of 105 ft over high water required by the Admiralty; rebuilt as an open lattice steel arch bridge by Husband & Co of Darlington on the masonry towers; reopened for rail 1972; the road deck begun October 1977 and opened 1980
  • Britannia Bridge Wikipedia, read 9 November 2026the 1970 fire (23 May); the arches built under the tubes, single-line working from 30 January 1972; the other tube replaced by a concrete deck, used only for service access, by 1974; the road deck by July 1980; 103 ft (31 m) to the bottom of the rail deck; four lions 25 ft long, 12 ft tall
  • Britannia Bridge (NPRN 34614) Coflein, read 9 November 2026rebuilt in 1972 as an arched steel structure on the original towers, a single line of railway; the upper deck 1980 (A55)
  • 67010 on Britannia Bridge (photograph) kitmasterbloke (Flickr), via Wikimedia Commons, 20 August 2019the arch's form and levels: scale 4.23 px a foot from the towers (centres 498.7 ft apart), the high-water line from the land tower's 190 ft; arch centre line at x = 1500..2600 px (springing about 10 ft over HW, crown 97 ft, rise 87 ft, parabolic within a foot or two, 16 panels of about 28 ft, rib about 3.6 ft deep); the rail deck 101.5-111 ft; the road deck 133-141 ft; the Britannia Tower 206 ft; the abutment tower 156 ft; two columns dividing the side span in three; the colours of the stone and the steel
  • Britannia Bridge from Church Island (7586) (photograph) Wikimedia Commons, 2013-14a second view (oblique, backlit): the arch springs at the land tower's foot, N-truss spandrels, the same deck arrangement; it confirms the form, not the numbers
  • Britannia Bridge Lion (photograph) Wikimedia Commons (geograph.org.uk)a lion couchant, forepaws extended, on a plain block plinth under the road deck
  • Britannia Bridge lions (a set of photographs on Wikimedia Commons, looked at on 9 November 2026) Wikimedia Commons (various photographers), 9 November 2026the lions' outline (no square side-on view was found: the profile is built from the side-rear view for the back, mane and haunch heights and from the front views for the head, chest and paws); the plinth's top about 11.5-13 ft over the rail (815381 and Isle of Anglesey (4), scaled on the lion's published 12 ft and a Class 175's 12 ft 3 in (3.73 m))
  • Britannia Bridge Train crossing 3 (photograph) Wikimedia Commonsthe other face, oblique: both arches, the Britannia Tower, a Class 221 on the side span with its lower body behind the rail deck's concrete edge beam
  • Class 805 services, London Euston to Holyhead and Holyhead to London Euston railchecker.app, June 2026Avanti West Coast runs London Euston to Holyhead with its Class 805 Evero bi-modes (they replaced the Class 221s in December 2024)
unverified
  • The ICE paper (Husband and Husband, "Reconstruction of the Britannia Bridge", Proc. ICE 58, 1975, pp. 25-66) and the drawings of Husband & Co were behind a paywall: the arch's rise (87 ft), span at the springing (448 ft), depth (3.6 ft), the number of panels (16 of 28 ft) and every level of the new decks are read off a photograph and scaled on the published tower and span figures. The photograph's tide is about 2 ft under high water (the land tower's foot at its edge, the soffit 102 ft over it, which agrees with Cadw).
  • The arch's shape is drawn as a parabola; it fits the photograph within about 2 ft. The N-truss: diagonals run from the deck's underside at one post down to the arch at the next, in the pattern the photograph shows on one half; the other half is mirrored.
  • Only the Anglesey half (the Anglesey abutment tower, side span and the Anglesey tower's main span) was seen on a level photograph; the Caernarfon half is drawn as its mirror about the Britannia Tower, as the 1850 bridge was symmetrical.
  • The abutment towers (40 ft along the line, 156 ft high), their foundations, the ground under the side spans and behind the abutments (a hillside here is a guess), the two columns' heights and bases, and the rock's shape are estimates; so are the Britannia Tower's base level (-10 ft, the rock's top at high water) and the strait's bed (-30 ft).
  • The lions: 25 ft long and 12 ft high (Clark 1849, the only published figure found; no figure for the plinths was found). The side-on outline is a schematic silhouette built from oblique and front photographs (no square side-on view was found); the tail lies inside the outline and is not drawn. The plinth's top, 12 ft over the rail, is read off two photographs along the track (11.5 and 13 ft); the plinths' length (29 ft), the forepaws at the plinth's outer end and the masonry under the plinth down to the ground are estimates.
  • The rail deck (BRG39 re-check, 9 November 2026): on 67010 the concrete edge beam is 110.75-119 ft and the train's lower body is behind it (the 67's roof at 125.9 ft, a Mark 4's at 124.9, so the rail at about 112.8); the steel deck is under it, 101.5-110.75. Britannia Bridge Train crossing 3.jpg (the other face, oblique) shows a Class 221's lower body behind the same beam. First drawn as one beam 101.5-111 ft with the rail on its top.
  • The towers' ornament (the plat bands at 102 and 132 ft, the cornice, the corner blocks, the relief panels) is simplified; the real piers have rectangular openings for the tubes on the line, which no side elevation shows.
  • The 1972 rail deck's ends and the junction of the concrete side spans with the towers, the road deck's parapet and the steel stanchions between the decks in the side spans are simplified.
  • The line speed over the bridge was not found; no crossing time is given.
  • The Class 805 is on the Euston-Holyhead service (railchecker, June 2026) and the site's record; Transport for Wales's Class 197 and its Class 67 and Mark 4 sets also cross.

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