EQUIPMENT | HARD ROCK EXCAVATION
HARD ROCK BARRIERS CUTTING THROUGH
A drum cutter solution to a tunnelling challenge on a Montreal metro project has challenged assumptions that only explosives or roadheaders can solve hard rock excavation needs. Early collaboration on the equipment specification is also vital to success, says Antraquip
Beneath one of Canada’s busiest city centers, crews faced a problem that most tunnelling professionals would expect only explosives to solve. A major Canadian contractor needed to excavate a deep shaft and drive a 117 yds (107m)-long metro tunnel, that is 32.8ft (10m)-wide and 23ft (7m)-high, through rock with uniaxial compressive strengths (UCS) ranging from 100MPa to 170MPa. This exceeded the limits traditionally considered possible for mechanised excavation technology like drum cutters or roadheaders. The location in Montreal made the challenge even
greater. Working directly under busy city streets meant vibration and noise had to be kept to a minimum, with no margin for error given the risk of damage to surrounding buildings and utilities. Drill and blast was ruled out from the start, not only for environmental and regulatory reasons but also for the logistical challenges explosives would pose in such a dense urban setting. The contractor needed a method that could cut hard rock cleanly, efficiently, and quietly, all while minimising the impact on the city streets above.
The solution to the different needs for the metro
excavations and their setting was to use Antraquip’s AQ 6 transverse drum cutter. Weighing approximately 8t and capable of delivering over 400kW of cutting power, the AQ 6 is a leader in power and performance within its class. For the project, the high powered drum cutter was mounted on a CAT365 excavator and powered by a dedicated hydraulic power unit. This configuration provided maximum stability, reach, and sustained performance in the face of constant high load cutting. The reinforced drums and robust transmission were engineered for prolonged operation in hard rock, giving the cutter the durability needed to take on a job like this. The excavation began with the shaft before advancing
into the tunnel heading. The site team followed a disciplined cycle - positioning the cutter for optimal engagement, maintaining steady feed pressure to balance penetration and tool life, while performing regular inspections to maintain the drums and cutter bits in peak condition. Dust suppression and ventilation were closely managed to ensure a safe working environment underground.
Above: Antraquip’s high-powered AQ-6 drum cutter was used to excavate hard rock tunnels in a sensitive urban setting for Montreal metro IMAGES: COURTESY OF ANTRAQUIP
34 | November 2025
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45
