The Monday Photo
Only three of the bridges that Walker and Co. of Rotherham made are left in the world, and Tickford Bridge in Newport Pagnell is one of them.
Built in 1810, it's also the oldest cast iron bridge in the world that carries modern traffic.
The other two existing bridges made by the company are older. The earliest one was built in 1801 in Spanish Town, Jamaica, and was the first cast iron bridge to be built in the Caribbean.
The other cast iron bridge was erected in 1802 on the estate of Stratfield Saye House in Hampshire, not far from Reading.
Walker and Co. also made cannon for the navy. It’s thought that around a quarter of all the cannon in Nelson’s fleet at the battle of Trafalgar were made by the company, and 79 out of the 105 cannon on the Victory bore the Rotherham firm’s WCo mark; they were an expert casting firm.
The Newport Pagnell bridge was cast in sections. It was taken by sea to London, then by boat along the Grand Junction canal, which had only opened five years earlier. It wasn’t too far by road from the canal to the site of the new bridge.
The old bridge over the Ouzel there had to be replaced as it had become “ancient and decayed”.
The new bridge had been designed with six arched trusses set side by side, linked together by plates. Each one is made of eleven separate vouissors (which work like the wedge shaped stones that form a masonry arch) joined together with mortise and tenon joints, held tight by wrought iron wedges.
The arches are under compression; they have to be as cast iron, like stone, is strong in compression but weak under tension. The railings and central lamp standards are also cast iron, and the bridge abutments are of local sandstone.
The bridge needed little work or alterations for ninety years, then in 1900 wrought iron plates were added to the two centre bays when one of the deck plates fractured.
In 1972 the stone abutments received extensive repairs. Four years later a reinforced concrete deck on plastic foam had to be laid over the bridge to evenly spread the load of modern traffic, but in 1999 the bridge had to be strengthened again with carbon fibre. This all works, as you can see by the bus.
In the mid 1990s bollards were installed on the bridge, creating a width restriction to stop lorries and other large vehicles. It wasn’t popular; the gap was too narrow and quite a few cars lost mirrors on the bollards.
I wonder now if the restrictions were there to protect the bridge until it could be strengthened again. If you know anything about all this, please comment below.
Tickford bridge is a very fine example of early civil engineering in cast iron, which is why it is Grade 1 listed.