CML Responds to Earthworks Emergency at Harlington - CML Civil Engineering

Track Defects call for Emergency Response

On 21st July 2025, CML responded to a planned emergency request from Network Rail at Harlington near Luton, after significant track defects were reported on the Up Slow (US) of the SPC1 line between Chesterfield and St Pancras.

Historical remedial measures had been installed at this location, comprising Grundomat king posts (~2.5m long) and lightweight GRP boards. However, the historic repairs were undermined by a rotational failure below the existing king post wall. A 60mph Emergency Speed Restriction had been in place since April 2025 due to repeated track voiding and a drop in the level of the 6ft rail. The remedial works also appeared to be bulging longitudinally, with visible track alignment issues extending to around 40m. CML has previously attended a failure in 2021 on the opposite line.

Scope of Work

CML’s engineering team produced a Form G design for the client to stabilise the dropped line using 8m long piles.

Works commenced at the end of July, including:

Vegetation clearance, ecology surveys and mitigation
Topographical and geomorphological surveys
Utilities and stakeholder liaison
Installation of 25m long piled wall along the toe of the embankment
Construction of a granular fill berm above the sheet-piled toe retention and 240-yard soil slope regrade
Gabion baskets installed at each transition
Reinstatement of toe drainage

Delivery Excellence

The project is on course for completion in early October 2025, delivering a long-term solution to a complex earthwork failure. This scheme highlights CML’s ability to combine rapid response, development of the design as construction progressed to accelerate the delivery programme, and site delivery expertise supporting Network Rail and stakeholders in protecting critical infrastructure.

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