Mottram Viaduct has stood above a 140ft high valley for the last 168 years, with few structural changes being made.
The scope of works included:
- Installation of a 2 level suspended scaffold, suitable to access all areas and provide protection to the homes, businesses, river and road beneath the structure
- 120 tonnes of expendable abrasive used in the removal of dilapidated paint and areas of corrosion
- 18,000 litres of new paint used to provide the structure with a protective system to last 25 years.
- 60 tonnes of new steel installed to allow the bridge to carry freight trains
- Overhead Conveyor system installed to move suspended plant and materials freely throughout the scaffold
- 745kg Concrete plinths & 75kg proprietary bearings moved into place using the conveyor and installed overnight during closures of the railway.
This five-span viaduct which crosses both a road and a river did not meet the Network Rail standards for carrying heavier trains or running trains at 60mph. Only two Sunday possessions were required, as the works were planned to ensure that there was no disruption to rail services or local residents. Restrictions in accessing the viaduct to evaluate the true extent of the work required proved challenging, and only when the access scaffold was in place could the true condition of the structure be assessed.
We were originally carrying out works to extract dust and debris overnight. However, due to the proximity of residents to the viaduct, the decision was taken to allocate additional manpower to ensure that the cleaning required at the end of every day shift was completed before night fell. This dramatically reduced the amount of disruption that residents experienced and ensured that they were supportive of TI and Network Rail throughout the project.
We also reduced disruption to residents and rail services by utilising on overhead conveyor system to move steel beams into position along the bridge. This negated the need to use of a trackside or roadside crane; eliminating the need for multiple rail possessions or road closures.
Learning and Innovation
This project proved to be one of the most challenging that we have undertaken. No matter how much research was done, it was impossible to fully access the structure and assess the condition and construction of it. Throughout the project, we discovered problems with the structure that were unforeseen, so we maintained an adaptable approach to the work we carried out. The lessons we learnt from this project were also carried forward to the work we carried out on Dinting Vale Viaduct, which is remarkably similar in its construction. We were in a much better position to foresee potential issues and allow for this in our planning.