First trains run on new Mott MacDonald designed Clifton railway bridge in Cumbria

The first trains have now crossed the new Clifton railway bridge near Penrith in Cumbria, marking the completion of one of the most complex rail-over-motorway bridge replacements undertaken in the UK. As lead designer for Skanska, Mott MacDonald played a central role in making this milestone possible, from early optioneering through to detailed design, multidisciplinary integration and onsite technical support during its installation.

The new structure carries the West Coast Main Line, one of the UK’s busiest and most strategically significant north-south rail routes connecting London, the Midlands, the North West and Scotland. Its predecessor, built in the 1960s, had reached the end of its service life and required full replacement to secure long term reliability for both passenger and freight services.

Delivering a major engineering operation at pace

Replacing a bridge over both a live motorway and a nationally important rail artery required a compressed programme and precise coordination. Working with Skanska, its supply partners and Network Rail, Mott MacDonald delivered the detailed design in just 12 months, allowing fabrication and construction to commence to meet the narrow and immovable railway possession window.

The new 4200t weathering steel box girder bridge, with its precast concrete deck, was built offline during 2025. This allowed the existing structure to remain operational until the start of the January 2026 blockade. Over the first weekend of the closure, teams demolished the old bridge; over the second, the new structure was moved into place using self-propelled modular transporters (SPMT). The installation was completed with millimetre precision despite subzero temperatures, and the M6, closed in both directions between junctions 39 and 40, reopened 13 hours ahead of schedule.

To reduce carbon impact and shorten the closure, the project reused the existing bank seats and piers, with strengthening taking place in advance. Mott MacDonald coordinated the multi‑disciplinary engineering design across civil structures, track and overhead power systems, using digital modelling to ensure interfaces were fully aligned.

A resilient bridge for the next 120 years

Designed for a 120-year life, the new structure secures a vital north-south connection for decades. Its installation is part of Network Rail’s wider programme of investment along the West Coast Main Line, with nearly £200M of improvements delivered between Christmas and mid-January alone.

The completion of the Clifton bridge renewal strengthens one of the UK’s most important transport corridors. With the new structure now carrying trains and the motorway fully reopened, both road and rail users benefit from a safer, more reliable link built to serve the next century of journeys.