Just before Christmas Bilfinger & Berger carried out a two week box jacking operation underneath the Trans-Pennine mainline route to create access to the business park from the A62 Oldham Road (pictured top right).
The 22m long, 28m wide and 5.6m internal/9.6m external height reinforced concrete box was slid into position just 800mm beneath the live railway, which was supported during the operation by a grillage of steel girders and plates. These were placed in advance of jacking during regular night time rail maintenance possessions.
Excavation was carried out by backhoe. Ground was stiff clay and the push was lubricated by a layer of sand placed beneath the box's base slab. As a precaution against the box sticking through skin friction the contractor planned to lubricate using bentonite, though in the event it was not needed, reports Balfour Beatty project director Peter Davis.