Newton Cap Viaduct
|Newton Cap Viaduct|
|Location Map ( geo)|
|1857 (railway) 1995 (road)|
|John Mowlam Construction|
|Crossings related to the A689|
Newton Cap Viaduct was originally built between 1854 and 1857 as a railway viaduct. It was converted to road use in 1995 and now carries the A689 across the River Wear to the north of Bishop Auckland. This road runs from Carlisle to Hartlepool.
The railway viaduct
The viaduct has 11 spans and is 252m long. The railway line closed to traffic in 1968 and the viaduct was bought by Durham County Council in 1972. It was converted to a footway two years later.
Initially it was intended to construct a new road bridge over the valley and civil engineering companies were invited to submit designs, The winning design was a six span structure but ground investigations found stabilisation issues which would add to the £2.4 million cost. The County Council highways department then looked at an earlier proposal to convert the railway viaduct and found it was not only feasible but would possibly be cheaper than a new bridge.
This was less than 10 years since the Council had proposed its demolition in 1984, citing it as unsafe. A local campaign group commissioned their own structural survey which gave a different picture to the Council's survey. English Heritage became involved and their survey showed that the viaduct did not need to come down. The campaign group put forward proposals that the viaduct could be converted to road use and this led to it being saved.
The viaduct originally carried two railway tracks and was 7.3m wide. This was insufficient for the scheme so the width had to be increased to 11.3m to accommodate the carriageway and two footpaths.
The original 19th Century plans were found of the similar viaducts at Durham and Belmont which assisted with the detailed drawings of the works required. The examination of the viaduct revealed a high standard of Victorian engineering and the deterioration since 1857 was not considered to be significant, although a lot of old masonry had to be replaced by the stonework specialists Bagrat. The new stonework was finished with Keim Restauro to give a colour match with the existing masonry. It also had a water repellent finish.
The existing ash ballast was removed and a new reinforced concrete deck slab with side cantilevers added. The deck was raised by one metre to allow more of the original masonry to be preserved and give access to the interior of the structure with a headroom of between two and three metres. The overall increase in foundation load was less than two per cent.
The main contractor was John Mowlem Construction. The conversion of the stone arch viaduct was believed to be a first of its type for the country, although there had been earlier conversions of railway bridges to road use. Greyhound Bridge in Lancaster had a new concrete deck added to the existing steel piers in 1972 and Filleigh Viaduct in Devon had a new deck added to stone piers.
It was re-opened for road use as part of the 1.1 mile Newton Cap Diversion and Toronto Bypass on 21 July 1995 by Derek Foster, MP for Bishop Auckland.
|Newton Cap Viaduct|