CELEBRATIONS are being lined up for the 150th anniversary of Kielder Viaduct, a bridge designed by a mathematician to have added historical interest.
Kielder Viaduct in Northumberland, now a scheduled ancient monument, was opened in 1862 as part of the Borders County Railway. This ran from Hexham in Northumberland to Riccarton Junction in Dumfries and Galloway.
The sandstone viaduct was built in the “baronial” style, with a castellated parapet and false arrow slits to complement the architecture of nearby Kielder Castle.
But as the railway line crossed the River North Tyne at an angle it was necessary to construct the seven arches at an oblique angle to the track and parallel to the river to minimise resistance from the current.
The result is a rare example of a skew viaduct, whereby the arches are built at a skewed angle – with each stone having to be individually shaped.
This construction presented a complex engineering problem which was solved by Peter Nicholson, a mathematician from Newcastle School of Design, who worked out the shape of each individual wedge-shaped stone for the arches so that those at the top would lie at a right angle to the viaduct’s deck allowing for extra strength and stability.
The viaduct is now considered to represent the finest remaining example of the skew arch form of construction.
With the closure of the railway line in 1958, the bridge, then under the ownership of British Railways, fell into disuse.
It was subsequently acquired by the Forestry Commission and was about to be blown up before the Northumberland and Newcastle Society stepped in to rescue it.
In 1969, the viaduct passed into the ownership of the society, which bought it for the nominal sum of £1 from the Forestry Commission.
In 2004, the society worked in partnership with Kielder Community Trust on a project to create eight iron panels installed between the parapets.
The panels were forged by six master blacksmiths, who interpreted designs by community groups in Kielder Village and pupils from Kielder First School.
The viaduct, 130 yards long and 55ft high, is part of the £3m Kielder Way, which encircles Kielder Reservoir.
A free walk across the bridge on New Year’s Day and along the former railway line meets at the viaduct, near Kielder Castle, at 11.30am.
Refreshments will be provided and booking is not required.