For many years the M60 Manchester orbital motorway has experienced congestion at peak times, caused by the volume of traffic, the interaction of local and through traffic and the fact that junctions are very close together.
A 7.5km stretch of the motorway between junctions 5 and 8 has now been widened to reduce delays and improve safety, with Halcrow undertaking all the detailed design.
Between junctions 5 and 6 the motorway was widened from three to four lanes in each direction, and between junctions 6 and 8 it was widened from two to three lanes in each direction, plus an additional two-lane collector/distributor road on either side of the main carriageways. Some of the junctions were completely remodelled.
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The £100 million scheme was tendered by Highways Agency as a design and build contract, and the winning contractor, a joint venture of Amec and Alfred McAlpine, appointed Halcrow for the design work. Our input included:
- innovative geotechnical solutions to widen the road over old landfill sites
- jacking existing bridge decks at one junction to allow them to be reused in the new road scheme; and
- designing the works in a way that allowed the contractor to build the scheme while keeping the traffic moving.
There were significant geotechnical factors on the project, including poor ground conditions and 12 licensed waste landfill sites, resulting in a need for extensive ground improvement using techniques including lightweight polystyrene fill, stone columns and load transfer platforms.
At junction five, where the M60 links to the M56 and spans Princess Parkway, Halcrow devised a new alignment to allow the existing structures to be re-used. The new anticlockwise carriageway now runs on a single deck formed by joining together two of the existing superstructures, which involved raising one of the bridge decks by 1.8m using a system of interlinked jacks.
Another innovation was the use of foam concrete to reinforce the abutment at Princess Parkway East Bridge, which was found to be too weak to carry new traffic loads. This cost-effective solution was also a lot easier and quicker then alternative strengthening options.
By retaining and modifying the bridges at junction 5, the team saved the Highways Agency around £2 million, as well as shaving six months off the original contract programme. Traffic disruption was minimised and the health and safety of the workforce was protected.