AARSLEFF PILING has finished phase one of a £146,000 piling contract for a new bridge on the M60 motorway on the south western outskirts of Manchester.
Completed in July, the work involved installation of 36 steel H-section bearing piles to support the central piers of the bridge at Junction 7, where the M60 crosses the A56 trunk road.
Working at night, Aarsleff installed the 16m long piles in clusters of twos and fours using a Banut 700 hydraulic piling rig with 5t drop hammer. The 305mm square piles were driven through a mixture of made ground, alluvium, clay, sands and gravels to found in the underlying siltstone.
Accelerometers and transducers fixed to the piles monitored dynamic testing of the steel columns, allowing testing company Precision Monitoring & Control to produce an instant readout of pile capacity.
Aarsleff piling manager Phil Chippindale said: 'The close proximity of the piling operation to live traffic required lane closures on the A56 and the adjacent M60 overbridge so the piles could be safely offloaded, handled and driven.'
Aarsleff 's contract is part of the project to widen the 7.4km section of the motorway, between Junction 5 at Northern Moor and Junction 8 at Stretford.
It will be broadened to three lanes in each direction and provide a parallel link road between Junctions 6 and 8. This will reduce congestion on the motorway and local roads.
The Highways Agency awarded the main £109M design and build contract to a joint venture of Amec Civil Engineering and Sir Alfred McAlpine Civil Engineering, who should complete the widening work in spring 2006.
The jv will build the new bridge in two stages, with the two southern spans coming first. Aarsleff will return next June to install the rest of the piles to support the central piers for the bridge's two northern spans.
Site workers will reuse some of the steel bearing piles from the original bridge's foundations.