Rail
Crossrail Acton Dive-Under
The Acton Dive-Under exists for one reason: to stop London-bound Crossrail trains being held up by freight trains entering and leaving Acton goods yard. BAM Nuttall brought TAG in to deliver the concrete that would carry the new track through it.
The track through the dive-under runs on a slabtrack system, precast concrete sleepers cast into a structural concrete slab, built to tolerances of just ±2mm on finished level. TAG's role was to prepare each bay ahead of the pour and then place and finish the ready-mixed concrete itself, work that leaves no room for a second attempt once the sleepers are set.
730 metres of slabtrack went in across 20-metre bays, all of it inside the narrow confines of the dive-under and the access constraints that came with it. TAG's crews still turned out two completed bays every two days, finishing the entire run in around two months. Every metre was finished by hand, working around the precast sleepers and underneath rails that were already in place, and the concrete mix used meant much of that finishing ran on a second shift, well into the night, to get the profile and surface texture right.
Once the slabtrack was down, TAG stayed on to complete the blockwork walls alongside it, forming in-situ dished drainage channels into the existing concrete walkways, installing GRP inspection and drainage panels into the finished blockwork, and raking out and preparing the slabtrack's movement joints ahead of sealant works.
Delivered for BAM Nuttall over six months for £79,000, the dive-under gave Crossrail the clearance it needed from Acton's freight traffic, built to millimetre tolerances by a crew willing to work through the night to get there.
Key Facts
Client
BAM Nuttall
Location
Acton, London
Contract value
£79,000
Duration
6 months
Slabtrack installed
730m
Finished level tolerance
±2mm
