Bridge 20 Reconstruction

Civils Stenson, Derbyshire 0.2M 11 Weeks March 2010

Bridge 20 Reconstruction

Bridge 20 Reconstruction

Background

Bridge 20 is a Grade II listed structure located on the Trent and Mersey Canal near to the village of Stenson.

The works were required to be completed in line with the Grade II listing and to the requirements of BW Heritage department and Local Authority Heritage Officer.

Bridge 20 is both a grade 2 listed structure and within the Trent & Mersey Conservation area, thereby providing two strands of legal protection.

Its listed status made it illegal to damage or alter the structure in any way without listed building Consent from the Local Authority (in this case South Derbyshire District Council). Like for like repairs and maintenance is however allowed so long as the materials are well matched.

Being in a conservation area makes it illegal to demolish a structure without Conservation area consent, and takes away standard permitted development rights.

The bridge was severely damaged in 2007 when a sludge tanker exiting the local sewage treatment works slipped off the bridge taking down half of the arch and the complete parapet wall to the eastern elevation. The tanker was left precariously suspended above the navigation.

The bridge was subsequently closed to through traffic. A temporary pedestrian footbridge was erected near to Bridge 20.

The reconstruction works involved the rebuild of the collapsed arch and parapet wall, the construction of a concrete saddle to support the arch and new structural fill approaches to the bridge.

The bridge had to be firstly supported and this was achieved by the installation of a scaffold support framework and timber centring to the profile of the original remaining arch. In order to effectively span the navigation with a scaffold support pontoons were floated to the bridge and sunk to provide a centre support bearing.

The bridge was to be unloaded evenly thus keeping the remaining arch in equilibrium.

Once the arch was supported and unloaded a further inspection revealed that the remaining section was in poor structural condition. A large crack was evident running north to south and additional work was instructed in the form of drilling and dowelling the remaining arch and new arch brickwork ahead of casting the concrete saddle, which was pumped in an even fashion ensuring the arch remained in equilibrium.

The works were completed on time, to budget and to a very high standard of workmanship. The finished works were accepted by all concerned parties.

Location: Stenson, Derbyshire Cost: 0.2M Duration: 11 Weeks Completion: March 2010