Media centre

Wednesday 6 Aug 2025

Railway heritage spotlight: 175 years of Britannia Bridge

Region & Route:

Wales & Western: Wales & Borders

From Victorian visions and fiery foes to foraging falcons and future-proofing fortifications - we dive into the rich history of Britannia Bridge as part of the Railway200 celebrations

Isn’t it supposed to be trolls that live under bridges? In fairytales, maybe, but not in Wales. Not on the way in and out of Anglesey, anyway. Instead, you’ll find four stone lions, a pair on either side, vigilantly watching over the borders to their lands. Above them, spanning the Menai Strait, you’ll find the resurrected Britannia Bridge.

Victorian vision

 

 

 

 

 

 

 

Britannia Bridge during its construction in 1848 showing partially completed piers in background - credit National Rail Museum (NRM) York

Originally opened in 1850, the Britannia Bridge was a pioneering structure of the Victorian age. Designed by Robert Stephenson, it was constructed as part of the Chester and Holyhead Railway, creating a direct rail route from London to Holyhead and onwards via ferry to Dublin.

Its groundbreaking design featured massive rectangular iron tubes through which trains travelled. The tubes, each weighing 1,500 long tons, were constructed on the Caernarfon shore, floated into position, raised using hydraulic jacks, then joined to form a continuous structure over 1,500 feet (460 m) in length. At the time, these were the longest wrought iron spans in the world. The tubes were supported by three masonry towers, the middle of which was constructed atop Britannia Rock, giving the bridge its name.

Stephenson’s bold design met Admiralty requirements for shipping clearance, including a headroom of 105 feet (32 m); enough for a fully rigged man-o-war ship to pass beneath.

For over a century, the railway bridge excelled at connecting communities and providing a vital artery for trade.

 

 

 

 

 

 

 

 

Robert Stephenson and celebrated engineers raising the tubular bridge conference, by John Lucas, circa 1858 - credit NRM York.

Phoenix from the flames

On 23 May 1970, disaster struck. Children playing inside the bridge accidentally ignited the timber-lined roof, causing a fire that severely damaged the structure. The intense heat warped the iron tubes, rendering them structurally unsafe.

Rather than demolish the bridge, a redesign was commissioned, resulting in the innovative two-tier steel arch bridge we see today. Rail traffic resumed in 1972, and by 1980, a road deck for the A55 Expressway was added above the railway line, transforming the bridge into a vital multi-modal transport artery.

Lion in wait

 

 

 

 

 

 

 

 

Britannia Bridge Lions standing guard - circa 1849 artwork - credit NRM York

Along with the preserved original masonry towers, another element of the original bridge remains. Four limestone lions guard the bridge, sculpted by John Thomas. Each stand 25 feet (7.6 m) long and 12 feet (3.7 m) tall, weighing around 30 tons. They were immortalised in local verse:

Four great lions, without any hair,

Two on this side, and two over there.

The lions are decorative sculptures symbolising strength and protection, meant to emphasise the bridge’s durability and grandeur. Though now obscured from road view, they still stand proud at the base of the towers.

Ongoing care and conservation

Network Rail Wales and Borders is responsible for maintaining the bridge and balancing modern operational demands with heritage conservation.

In 2011, a £4 million joint project by Network Rail, the Welsh Government, and the Highways Agency strengthened the structure and restored key elements, including parapets and steelwork.

2014 saw the addition of movement and vibration sensors to monitor the bridge’s condition.

In 2021, fibre-reinforced plastic beams were carefully installed beneath the historic lintels to preserve the Grade II-listed towers, safeguarding their stability for years to come. Notably, work on the central tower was briefly paused to protect a pair of nesting peregrine falcons, highlighting the balance between preservation and nature.

An epitaph to genius

Britannia Bridge plays a vital role in carrying transport from Wales to Anglesey, with the changing shape of rail and road traffic marking the passage of time.

Stephenson’s professional rival and friend, Isambard Kingdom Brunel, upon viewing the completed Britannia Bridge, reportedly remarked:

“If your bridge succeeds, then mine have all been magnificent failures.”

Robert Stephenson's engineering legacy lives on in a memorial in Westminster Abbey. A stained-glass window in the Abbey’s north choir aisle features a medallion depicting the bridge standing proud over the straits.