Revolutionary way to widen road

A Blaw-Knox road widener, fitted with a specially shaped blade looks set to revolutionise the technique for constructing drainage channels in hot-rolled asphalt along the edge of motorway carriageways.

Work recently carried out for Balfour Beatty Civil Engineering by Kent-based Exactonne Asphalt on the M6 widening project near Preston, has shown construction of drainage channels by the Blaw-Knox RW-100A road widener to be five to six times quicker than the old method of hand-laying, and cheaper than using extruded concrete.

Simon Morris, Balfour Beatty's project manager said:'The contract involved widening the M6 carriageways, between junctions 30 and 32, from three to four lanes in each direction.

'We took the opportunity to move drainage collection off the carriageway and constructed a drainage channel in blacktop alongside the central reservation. We felt that the Blaw-Knox road widener, suitably modified would produce the required profile.'

Armed with a new blade, the result of work by David Tomkinson at Exactonne Asphalt, the machine met Balfour's requirements. The design of drainage channel used for the M6 employed a wide offset 'V' shape, 1.5m across and 100mm deep.

The channel was constructed from two 75mm layers of type 1 stone foundation course, and a final 40mm wearing course of HRA. Each layer was laid by the Blaw-Knox machine and then rolled by a small roller. Using the widener and a single gang up to 600t per day were laid. Conventional hand-laying would have reduced production to around 100t a day.

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