Through close collaboration with Skanska Costain STRABAG JV and Herrenknecht, a gantry solution was custom designed and assembled – which provided significant benefits. Rise of the machinesFour TBMs were used to excavate the 8.4-mile Northolt Tunnel section of the HS2 route. Design of the custom-built gantry system began around nine months prior to execution. Creating the gantry systemWhile much of the equipment used to construct the gantry system already existed, it had never been assembled into this arrangement. We created a system that could be remote controlled for ease of operation,” explains Sam Ellwood, lead engineer at Mammoet.