Larger vertical access for trenchless tunnelling equipment

The larger diameter units will allow contractors to construct 4m vertical shafts for jacking and reception pits or may be adapted as manholes in open-cut construction. For handling during transportation and installation, the new caisson is produced as two semicircular segments, 1m or 0.5m deep, the 1m sections weighing 3,220kg. The two halves are bonded together with resin mortar on site. Each half of the lead caisson is factory-fitted with a mild steel cutting shoe, finally welded into a complete ring on site. Milton provides steps, rest platforms, covers, landing and half-landing slabs where required. Milshaft rings are designed for rapid manhole installation in most ground conditions. Each section can be sunk under its own weight or pressed into the ground using a conventional excavator. As well as the new 4m ring, they are available in most standard diameters, including 2,400mm, 2,700mm, and 3,000mm.

For further info contact +44 (0)1795 425191