Caldew Viaduct
The design and build project delivered a robust scour mitigation and repair solution for Network Rail, improving structural resilience and hydraulic conveyance for a critical rail asset on the River Eden.
Network Rail
£3m
The project involved the following main phases:
- Site investigations, including trial holes and boreholes, to inform the assessment of existing conditions.
- Preparation of a feasibility report evaluating suitable scour mitigation options, including associated costs and benefits.
- Detailed design of the agreed scour mitigation measures and substructure repairs, reducing the Level 1 Risk Assessment score to ‘Low’.
- Installation of pollution prevention measures.
- Installation of temporary works to facilitate construction activities.
- Partial dewatering of the working area to enable a fish rescue, undertaken by a licensed ecological contractor.
- Full dewatering and maintenance of the working area.
- Repair of substructure masonry defects above and below the waterline, including crack stitching and grouting, repointing, and local masonry replacement.
- Installation of a new reinforced concrete slab invert tied into the existing structure, along with upstream and downstream rip-rap toes and bank protection works to the eastern and western extents of the watercourse.
- Installation of rock armour toe protection.
- Improvement of conveyance through the asset by opening up adjacent spans, allowing increased hydraulic flow through the structure.
A detailed understanding of river behaviour, bed profile and constraints was central to the project’s success. Bathymetric surveys and flow analysis informed both the design and construction methodology, and identified previously unrecorded sewer pipelines beneath the riverbed. Through close collaboration, these assets were safely accommodated and fully integrated into the final solution.
Works were carefully planned around ecological sensitivities, with
methodologies agreed with the Environment Agency and Natural England to protect salmonids, lamprey and otters within the River Eden Special Area of Conservation and Site of Special Scientific Interest.
Carbon efficiency, constructability, flood resilience and whole‑life performance were embedded within the design process, delivering a robust solution that reduced scour risk while increasing hydraulic conveyance through the viaduct.
The project was managed from Story Contracting’s Carlisle office and delivered using in‑house site managers, engineers and operatives, supported by specialist supply‑chain partners.
Story Plant provided operated plant using bio‑fluids, while specialist cofferdam systems were selected to allow rapid removal during flood events, ensuring no increased upstream flood risk.
Strong collaboration underpinned delivery, with close engagement across Network Rail, Story, the Environment Agency, Natural England, United Utilities and the local authority, Cumberland Council.
A proactive Flood Contingency Plan, regular safety rehearsals and DEFRA water rescue training ensured workforce safety throughout the works, contributing to over 37,000 accident‑free hours.
The scheme was completed ahead of programme and under budget, achieving first‑time acceptance and delivering long‑term resilience for this critical rail asset.
37,000+
accident free hours
worked on site
417
fish were safely
captured and relocated
15.64%
biodiversity
net gain
After many overtopping events, fish rescues, thousands of sandbags and pump re-locations, thanks is in order for the perseverance of the Caldew delivery team. Photos don’t do justice to the undertaking and hard yards the team has put into making Phases 1 & 2 a success. Well done and thank you to all involved.
Keith Sanderson, Construction Manager
Network Rail