Custom-Built Gantry Speeds HS2 TBM Removal

Mammoet has developed a gantry system to extract four Tunnel Boring Machines (TBMs) used on the High Speed 2 (HS2) rail project, enabling safer and faster removal of the giant equipment.

The TBMs, manufactured by Herrenknecht, were deployed to excavate the 8.4-mile Northolt Tunnel between Birmingham and London. Traditionally, dismantling such machinery underground is hazardous, involving confined spaces, fumes, and heavy manual work. Instead, Mammoet’s system allowed major sections – including the cutter head, front, and middle shields – to be lifted intact to the surface.

Working with Skanska Costain STRABAG JV and Herrenknecht, Mammoet designed a gantry capable of lifting up to 900 tonnes. Mounted on a hydraulic skidding system, it could move between the two ventilation shafts, rotate loads remotely, and place them onto Self-Propelled Modular Transporters (SPMTs) for transfer to ground-level disassembly.

This approach cut removal time dramatically: TBM sections could be lifted out in a single day rather than weeks. The safer, “hands-off” operation also reduced the need for workers to handle loads directly or work at height.

“The solution avoided congested underground dismantling and delivered large time savings,” said Darren Watson, Sales Director at Mammoet. Richard Dexter, Managing Director of Herrenknecht International Ltd, added that the operation demonstrated the strength of long-term collaboration: “It has been one of the smoothest real-time demonstrations of relationships developed over many years.”

The custom-built gantry not only accelerated HS2 progress but also showcased a versatile solution for future projects requiring heavy lifting in restricted spaces.