5,500kg CHP Unit Into a Basement With 40mm of Headroom

40 Marsh Wall is a residential skyscraper in the heart of Canary Wharf. The building's basement plant room needed a 5,500kg combined heat and power (CHP) unit installed, but the access route presented a problem that ruled out every conventional method of getting it there.

The basement entrance had just 40mm of headroom above the unit - barely enough to slide a hand over the top. That alone made wheeled transport impossible: no machine skate capable of carrying 5.5 tonnes has a low enough profile to operate in that clearance. But the real complication was what lay beyond the opening: an immediate drop of 1,100mm to the basement floor level. The unit had to pass through a gap it barely fitted into, then somehow be lowered over a metre to the floor below, all without damage to the unit or the building.

This was a live construction site in one of London's most prominent development areas, with the main contractor O'Halloran & O'Brien coordinating multiple trades around us. The CHP needed to be off the street and into position quickly to avoid disrupting the wider programme.

With no off-the-shelf equipment capable of handling the combination of weight, clearance and level change, we designed a bespoke method to get the CHP from street level to its final position in the basement.

The core of the solution was a low-friction sliding system. We laid multiple layers of 2mm Teflon  sheeting, lubricated between layers, to create a surface the unit could slide across with minimal resistance and virtually zero additional height. At only 2mm per layer, this kept us within the 40mm clearance envelope that conventional skates couldn't meet.

To bridge the 1,100mm drop, we constructed a solid block platform that filled the void completely, bringing the basement side level with the entrance threshold. The onsite tower crane placed the CHP unit onto the Teflon sheeting at the entrance, and a Tirfor winch - mechanically fixed to the building structure for a secure anchor point — pulled the unit across the low-friction surface and into the basement, sliding it onto the block platform.

Once the unit was inside and clear of the street, we began the staged lowering. Using four toe jacks, we raised the CHP off the block platform and removed one layer of solid blocks. The unit was lowered back down, and the process was repeated - layer by layer - until the CHP was at basement floor level. From there, it was placed onto machine skates and moved into its final position in the plant room.

The 5,500kg CHP unit was slid through the 40mm clearance, lowered through the full 1,100mm level change and positioned in the basement plant room within a single day. The unit sustained zero damage, the building structure was unaffected, and the operation was completed without incident.

What was inherently a high-risk activity — five and a half tons through an opening with almost no clearance and a significant drop — was reduced to a low-risk, fully controlled operation through careful engineering of the method. The unit was off the street and inside quickly, keeping the main contractor's programme on track and avoiding any disruption to the wider Canary Wharf site.