Bridges and viaducts › Conwy Railway Bridge
Conwy Railway Bridge
Stephenson's tubular bridge over the Conwy, opened in 1848: a span of 400 ft (122 m) between castellated towers, the tube 412 ft (126 m) long and 25 ft 6 in (7.8 m) deep, 18 ft (5.5 m) above high water.
- Opened
- 1848
- Line
- North Wales Coast Line (Chester to Holyhead)
- Kind
- Tubular girder
- Length
- Tube 412 ft (126 m)
- Span
- 400 ft (122 m) between the towers
- Tube
- 25 ft 6 in (7.8 m) deep at the centre and 15 ft (4.6 m) wide
- Clearance
- About 18 ft (5.5 m) above high water
- 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 ↓
Four times larger
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.
Sources
How we source figures → · Spotted a mistake? Tell us → (opens in a new tab)
- An Account of the Construction of the Britannia and Conway Tubular Bridges William Fairbairn, 1849, pp. 184-185, 191-194tubes 412 ft long, 25 ft 6 in high, 15 ft wide, not less than 1,300 tons; the table: span 400 ft, height 25 ft 6 in at the centre and 22 ft 6 in at the ends, 14 ft 8 in; the tops a parabolic curve (the Britannia tubes alone cambered below); a clearance of 12 in between the masonry and the tube; the final position not more than 18 ft above high water
- The Britannia and Conway Tubular Bridges, vol. I Edwin Clark, 1850, pp. 9-12the least span 400 ft, the height above the water 18 ft, matching the suspension bridge; 50 ft from the suspension bridge at the Chester end and 65 ft at the Conway end; the channel 240 ft broad and 63 ft deep at high water; the tide's range about 21 ft
- Conwy Railway Bridge (listed building 3236, Grade I) Cadwashlar rectangular castellated towers with blind arrow loops, lower round turrets at the outer corners, smaller corbelled round turrets at the inner corners; two round concrete-filled cast-iron piers set back from each end, added 1899
- Conwy Railway Bridge (citing the North Wales Weekly News, 22 September 1899, and the Wrexham Advertiser, 7 October 1899) Grace's Guidein 1899 the span was reduced by 90 ft by two pairs of cast-iron columns; their greatest depth in the river bed 70 ft; the Cleveland Bridge and Engineering Co. from 1896
- OpenStreetMap OpenStreetMap contributors (ODbL), read 8 November 2026the span between the towers' river faces, 402 ft; the towers' plans (the east tower 33 ft deep, the west 26 ft); the tracks 23 ft apart
- Stephenson's Tubular Bridge (photograph) Richard Hoare, via Wikimedia Commons (geograph.org.uk), 30 September 2010the upstream face from about 558 ft (170 m) away, nearly square on: the towers' and turrets' heights, the tube's depth at the centre and ends (147 and 130 px, 1.13 to 1, as printed), the 1899 columns' places, the beach
- Conwy Tubular Bridge (lithograph) T. A. Picken, via Wikimedia Commons, 1849the towers and tubes as built, before the 1899 columns: a check on the turrets' arrangement
unverified
- The tube's soffit is drawn 18 ft above high water: Clark and Fairbairn give 18 ft as the height above high water without saying whether it is the soffit or the rails; it matches the suspension bridge's headroom, so the soffit is taken. The rails are estimated 2 ft 9 in above it (the bottom cells and the timbers).
- The cells are drawn 2 ft deep at the top and the bottom, from the photograph (Fairbairn's letter of February 1847 proposed cells 1 ft 8 1/2 in square). The T-iron stiffeners are drawn every 2 ft (Fairbairn: side plates 2 ft wide, the joints covered by T-iron).
- The towers' depths along the line are read off the photograph between their river corners and the outer turrets' centres: the west tower 34 ft, the east 29 ft (OpenStreetMap's outlines give 26 ft and 33 ft; the east agrees, the west doesn't, and neither is published). The outer turrets are about 16-18 ft across on both. The clear span between the river faces is drawn the printed 400 ft (OSM 402 ft); on the photograph the corners stand 389 ft apart at the tube's own scale, about 3% short, which a compact camera's barrel distortion near the frame's edges would explain, so the photograph's positions are scaled to the printed span.
- Every tower and turret height is read off one photograph (geograph 2089361, Richard Hoare, 2010), each scaled by the tube's own depth at that end (22 ft 6 in = 131 px at the west end, 128 px at the east), within about 2 ft; the two towers read 2-3 ft apart (the west main tower's merlons 86.9 ft above high water, the east's 84.6 ft) and are drawn as read. The crenellations, corbel tables, spurs and arrow loops are simplified.
- The inner turrets are drawn corbelled out at the towers' river corners, about 11-12 ft across, as Cadw describes them and as the photograph shows them.
- The 1899 cast-iron columns are drawn where the photograph puts them: the west one's centre 48.6 ft in from the west tower's face and the east one's 55.3 ft in from the east face (its east edge is lost in the tower's shadow, so that one is the less sure), about 13 ft across with a 15 ft cap. Grace's Guide (from the North Wales Weekly News, 22 September 1899) says the span was reduced by 90 ft, which would put them about 45 ft in. Their diameter isn't published, and the photograph can't say whether each is one column or two side by side.
- The river bed is estimated: the beach under the west end from the photograph at low water, the channel's 63 ft at high water from Clark (said of the channel between the castle rock and the island, 50-65 ft downstream), the east tower on the island's rock.
- The approaches' parapet walls are drawn at 3 ft 9 in over the rails, read off the photograph; their lengths beyond the towers are not drawn to any plan.
Know a source for one of these? Send it to us → (opens in a new tab)