| Skanska and Walters Weymouth Relief Road |
| 09 October 2009 |
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If the town of Weymouth nestling in a fold on Dorset's coast doesn't sound like a place desperate for a traffic alleviation scheme then try driving into the town during the summer. Even on a drizzly Wednesday the traffic crawling bumper to bumper down the A354 to the north of the town is the sort more normally associated with central London rather than one of the south west's oldest ports. It is difficult enough to see how Sir Christopher Wren managed to shift thousands of tonnes of Portland Stone from the area to build St Paul's Cathedral but it is stone of a different hue that specialist contractor Walters UK is clearing in the latest bid to help alleviate traffic problems in the area. Jointly funded by the Department for Transport and Dorset County Council, the £87.5m Weymouth Relief Road will see 7km of new carriageway built to help improve travel times between Weymouth and Dorchester, relieving some of the pressure from local residents. The project has had a troublesome past, spending more than a quarter of a century sitting on various drawing boards. But now all eyes are on Walters and main contractor Skanska to deliver the full project by spring 2011, in time for the thousands of tourists expected when Weymouth hosts the 2012 Olympics sailing regatta. For now, though, Walters director Colin Chambers and his site team are more concerned with the movement and management of more than one million m3 of earth and stone that needs to be excavated and replaced along the line of the scheme under its £8m bulk earthmoving contract. Most of this mammoth muckshift has to be carried out in the first season with only small levels of work, other than the necessary landscaping commitments, continuing into the 2010 summer and beyond. Logistics issuesThe earthmoving fleet of equipment that Walters operates is more than capable of handling that level of muck shift, but the problem on a project such as the Weymouth Relief Road is not just one of extraction capacity, it is the actual logistics of handling that volume of material and working out when to extract it and where to place it that causes the real problems. "If you work out the capacity that the Walters Group has then the actual volume of material is not the issue. "We have a fleet more than capable of shifting 25 million m3 and we do so through our open-cast mining division. But in those instances the sites are huge and there is always plenty of room to work. Here, like all road jobs, we are on a long thin site which makes it more difficult - consequently the volumes drop," explains Chambers. And despite this year's unusually wet summer that has seen parts of Devon, Dorset, Somerset and Cornwall hit by torrential rain, the Walters team have managed to keep its fleet of wagons and excavators moving for most of the period. "It's not been that bad for us actually," says Chambers. "We had a good start to the season and then had some scorching weather. It's only been August that has really hit us." Minimal delaysSeeing a fleet of a dozen or so predominantly Volvo 40 Tonne dumpers parked next to one another waiting out the downpours may have most fleet managers gnawing their nails and staring skyward, but Chambers seems relaxed. "Generally the material drains well so, while we have had to park up our wagons and stop work, the delays have been minimal," he says. With underlying rock strata varying along the length of the road from coralline chalk and limestone in the north through Purbeck and Portland stone and on into clays and landfill in the southern section the team is well pushed to achieve its goal of balancing out cut and fill levels along the route. That there will be no extra material brought on to the site under the earthmoving contract is thanks in many ways to the ECI contract that enabled Walters UK to get involved in the scheme at a very early stage. "We have been able to have some input in the design thanks to the early contractor involvement. It has meant that we have been able to work alongside Skanska and its design partner Amey. In fairness, on this job there was already an in-depth design, so we were able to work out the quantities in detail during the tender process and manipulate the design if we needed to," explains Chambers. "The true art of muck shifting is to never stockpile. We want to move any material just once - we want to excavate it then put it straight to bed." A plant fleet that includes two 85t Caterpillar excavators, D8 and D9 dozers also from Caterpillar and fitted with rippers where appropriate as well as a host of smaller Komatsu excavators has been making short work of the 1.1 million m3 shift. And on a scheme where so much depends on the first season of the construction programme Chapman and the rest of the project team is aware that a lot rests on Walters' ability to deliver. Most of the site is given over to the specialist so that it works in isolation, particularly where the larger pieces of equipment have been used, helping improve productivity and safety. "The key to this job is getting the earthworks done by the end of the first season. "The rest of the project team recognise that and have allowed us exclusion zones so that we can work without worrying about other contractors," explains Chapman. Application for accessIf other contractors needed access to these zones then a written application is made explaining where, when, why and for how long access is required. These are then signed off by the Walters team and discussed in a daily earthworks briefing. "It means that drivers can get on with their work without fear of injuring others with their machines," says Chapman. "It's really about controlling the area around machinery and keeping it clear of people as far as possible," he adds. By the end of October most of the bulk earthworks will be completed, which will enable Skanska to move on to the next phase of delivery and Weymouth's residents closer to journeys free from the frustration of tailbacks. Embankments blend in The design of the embankments, cuttings and particularly the top and bottom of the batters has meant that Walters has used the latest technology to help improve the final look of the scheme. Instead of the usual square engineered edge to the cuttings and embankments client Dorset County Council has insisted their cross section mimics the rolling chalk downland surrounds by tapering away and blending into them. Walters has used its GPS controls on its dozers to help drivers 'roll' the edges of the batters to the exact design requirements. "The driver has the digital earthworks model in the machine and this helps us provide the rolled edges of the batter the client wants," says Chapman. Fact File
The above article is taken from the Contract Journal which featured Walters and the Weymouth Relief Road. |
