The Morton Partnership had the honour of acting as Project Lead and Contract Administrator for the Ironbridge Restoration Project
Our works to provide engineering and technical input were on behalf of English Heritage, with the works their single largest conservation project to date.
The bridge has significant historic, engineering and cultural importance with this being the first single span arch bridge formed in cast iron. Its construction marked a key point within the Industrial Revolution, with the gorge very much at the forefront of this. Understandably the gorge is now a World Heritage Site and the bridge protected as a scheduled ancient monument, with Grade I Listing.
There has been a long history of movement of the gorge which has affected the bridge due to unstable ground, this has resulted in the substantial distortions and dislocations, as well as the previous remedial efforts. It is reasonable to say that the current and most likely greatest influence (in our view) on the condition of the bridge is the slow process of corrosion jacking. Inherently, the carpentry type construction of the ironwork frame with mortise and tenon and other interlocking joints creates largely inaccessible pockets in which corrosion can gradually advance.
With respect to the repairs undertaken, there was clear focus on these being reversible in nature and, in many cases to radials and main frames were containment repairs. In addition, corrosion was removed to a thorough extent where practically possible and all of the cast metal further protected through application of a paint system to minimise water and air ingress.
Other noteworthy repairs and works that took place during the restoration project were the replacement and recasting of individual iron wedges that lock between the deck plates and frame ribs, masonry repointing/repair works and installation of a new road build-up and surface incorporating a waterproof membrane.
Client: English Heritage
Architect: Ferguson Mann