Highways

A40 Northolt Underpass Retaining Wall Strengthening

FM Conway and TfL needed the stone cladding on the A40 Northolt underpass retaining wall reinforced before it posed a risk to the carriageway below. TAG's brief was to drill and fix 1,200 tie bars to secure the cladding, repoint 6,000 metres of mortar between the stones, and lay new stone where it was needed.

Every bar had to be drilled and fixed with high-strength resin and a sleeve to stop grout loss, on a wall running directly alongside a live carriageway that forms one of the main routes in and out of London. Logistics had to be planned around keeping that traffic moving throughout.

TAG carried out the full contract package on both sides of the carriageway inside a five-week programme, finishing a week ahead of schedule for both FM Conway and TfL, and carried out the pull-out testing and reporting needed to confirm the reinforcement was performing as designed.

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