Legato® Blocks Secure the Settle to Carlisle Rail Line at Risehill Tunnel

For anyone who has ever stepped on a Lego® brick, it’s easy to understand the pain but also appreciate the genius of interlocking blocks.

While Lego® inspires creativity in children, a similar principle was applied to solve a major engineering challenge in Cumbria, where the Settle to Carlisle railway line faced ongoing drainage and embankment stability issues.

Near the southern portal of Risehill tunnel, close to Dent station, excess water was threatening the stability of the railway embankment. Network Rail, under a framework contract with Story Contracting, needed a robust, permanent solution.

The answer lay in Elite Precast Concrete’s Legato® interlocking blocks – a full-scale, heavy-duty equivalent of the world’s most famous building toy.

• Remote location: The embankment is located high on the Pennine moors, accessed only by a 1.4-mile haul road across challenging terrain.

• Harsh environment: Persistent rainfall and a fast-flowing beck (Cowgill Beck) caused ongoing erosion at the embankment toe, leading to slumping and track alignment issues.

• Logistics: Large construction plant and materials had to be transported via steep, narrow routes, with the largest machinery, a 22-metre-long reach excavator, even tracked several miles from Garsdale station.

Given the location and site constraints, conventional in-situ concrete pours were ruled out. The solution needed to be modular, transportable, quick to assemble and highly durable.

A three-phase programme of drainage and embankment strengthening was undertaken, culminating in the reconstruction of the embankment toe. At the heart of this solution was the creation of a complex precast concrete weir and retaining wall system, designed to:

• Slow the flow of Cowgill Beck during spate conditions.

• Protect the embankment toe from further erosion.

• Support the reconstructed railway slope above.

Elite Precast Concrete’s Legato® interlocking blocks provided the ideal system. Produced in Telford, the blocks are cast from high-strength concrete, weigh up to 2.5 tonnes each and feature a simple yet effective male/female interlocking system.

The engineering consultant AECOM, working alongside Story Contracting, designed a stepped revetment and retaining wall entirely from Legato™ blocks. Much like Lego®, the blocks were assembled as a “kit of parts,” making off-site design and on-site construction highly efficient.

• 245 Legato® blocks were delivered to site and installed.

• Each block, fitted with lifting eyes, was easily placed into position using site plant.

• Wet concrete foundations were poured to provide a secure base, after which the Legato™ blocks were stacked to form the retaining structure and stepped weir.

• A physical Lego® model of the structure was even used as a briefing tool on site, as a practical demonstration of how the real-life “building blocks” would be assembled.

• Long-term embankment stability for this critical section of railway.

• Improved drainage management, safeguarding the line against future landslips.

• Rapid, efficient installation thanks to the modular nature of Legato® blocks.

By replacing in-situ construction with a precast solution, the project team reduced on-site risk, minimised disruption and delivered a permanent, durable solution in one of the most challenging rail environments in the UK.

Legato®interlocking blocks proved the perfect answer to this high-profile civil engineering challenge. Their adaptability, strength, and ease of installation allowed Story Contracting and AECOM to deliver a safe, reliable and innovative solution, protecting one of Britain’s most iconic railway lines.

For Elite Precast Concrete, the project remains an example of how its products can support infrastructure built with long-term performance in mind. Ten years on, its central lesson is still relevant: successful civil engineering depends on the right design, the right products and effective collaboration

Photos courtesy of Stuart Marsh.