Dundalk Western bypass nears completion

The Celtic Roads Group was awarded the contract to design, construct, finance, operate and maintain for a concession period of 30 years, the M1 Dundalk Western bypass. Construction manager Ian Cunningham is confident the route will be completed ahead of its February 2006 completion date.

The route will form an integral part of the M1 corridor

The M1 Dundalk Western bypass will form an integral part of the M1 corridor from Dublin to the Border, when it opens in spring 2006. The Celtic Roads Group would consider this project to be a demonstration of what effective partnership can achieve for the delivery of the National Development Plan.
Currently the motorway terminates south of Dundalk, and all traffic must pass through the town with resultant delays and congestion difficulties. The new 12 km stretch of road, which stretches from Haynestown to Ballymascanlon, will reduce travel times by up to 30 minutes at peak times.

Under the terms of the public / private partnership, the Celtic Roads Group comprising HBG Ascon Ltd, NTR PLC, Edmund Nuttal Ltd and Dragados Consesiones de Infraestructuras SA, a major Spanish firm will construct the 12kms of motorway, along with approximately 7km of new link roads, 12 over / under bridges and a major railway bridge.
In addition the consortium will take over the operation and maintenance of 43km of existing motorway from Haynestown to Gormanston, including the recently constructed Boyne Bridge and adjacent toll plaza for a 30-year period.

As part of the deal the consortium also took over the operation of the toll plaza adjacent to Drogheda. “We also had to upgrade the toll plaza to include dedicated electronic non-stop toll collection lanes as part of the contract,” Ian confirmed.

The project commenced in early February 2004 when the consortium signed the contracts, for what is only the second major inter-urban Public / Private Partnership scheme awarded under the National Development Plan 2000 - 2006.
“The concession runs for 30 years from February 5, 2004 when the contracts were signed. The completion date for the construction is February 11, 2006, but we hope to open ahead of schedule,” Ian enthused.

Advanced archaeological works had been carried out prior to the awarding of the contract. This allowed the consortium to begin ground clearance within a matter of days of signing the contract. “Because of ecological factors we had to have the site cleared before the end of March. We would be talking about removing hedges and so on,” he added.

Topsoil stripping was quickly followed by what is known in the trade as “cut and fill.” “Basically it means cutting out material in one location and moving it to another. There were a number of rock areas, which we exposed at an early stage to give us a head start. We extracted a large amount of rock from an area adjacent to the Armagh road. That rock was later used in the construction of the road pavement,” Ian explained.
As with all civil engineering projects, the M1 Dundalk Western bypass threw up certain challenges for contractors. None more so than the construction of a railway bridge on the Dublin to Belfast line.

“There were 14 structures along the motorway - 10 road bridges, two river bridges, one pedestrian under pass and a railway bridge. The railway bridge posed the biggest challenge,” Ian confirmed.
Using a technique known as Autoripage, the bridge was constructed some 40 metres from its final resting place, before being slid into position. “The technique is commonly used across Europe, although this was the first time it was used in Ireland,” he added.
The bridge, which weighed in at7,500 tonnes and took 25,000 man-hours to build was slid into position over the Easter Bank Holiday Weekend, following an operation that was planned with military precision.

After Iarnrod Eireann removed the existing rail tracks, the excavation of the embankment commenced at 00.01 hours on March 24th and continued for 20 hours by which time some 23,000 cubic metres of material had been removed.

“Using some of the biggest excavators in the country it took almost 20 hours to remove the embankment. It was a difficult operation, but it went very smoothly nonetheless.”
The excavation was carried out by two CAT 365 excavators, a CAT 385 excavator, supported by two track excavators and a dozen Volvo A40 dumps trucks to haul away the material.
Ian elaborated: “The technique is complicated to explain but simple in its principle. The bridge was built on a base slab, which in turn sits on a guide raft. Cables from the back of the bridge in the base slab run along channels to a point below the ground where they are anchored to the guide raft. By pulling on the cable the bridge moves forward and slides into place.”
In total the bridge travelled 44 metres to its final position, supporting the Dublin to Belfast railway line. “The Autoripage technique was chosen because we could only shut the Dublin to Belfast line for a short period of time. The line was closed for 72 hours over the Easter Weekend. The line reopened on Easter Monday,” Ian affirmed.

While it only took 72 hours to slide the bridge into place, its construction took somewhat longer. “We started constructing the bridge before Christmas. The bridge weighed 7,500 tonnes and took a lot of man-hours to construct,” he noted.
While construction of the motorway began at the southern end construction work didn’t follow a straight line. “We would have opened up several fronts at the same time. It’s not like building a house where you start at the bottom and finish at the top,” he elaborated.
He continued: “Civil engineering allows you the opportunity to work on several areas at the same time in and ordered and timely fashion.”

Once the “cut and fill” is complete the contractors then proceed to lay a “capping layer.” “The purpose of the capping layer is to provide a platform for the construction of the road paving. We are using a gravel that is graded from five inches down. Some of that material was produced on site, while the rest was imported from local suppliers,” he affirmed.

A layer known as CBM is then placed on top of the capping layer. “CBM stands for cement bound material. It isn’t widely used in Ireland. We processed the rock found on site and batched it with the cement on site. The whole process was contained on site,” Ian explained.
Once the CBM layer is complete drainage, dressing and the final layers of bitumous will be addressed before the final layers of bituminous pavement are laid. “After that stage you would be approaching completion and road signs and safety barriers would be put in place. One of the final jobs is putting down the road markings,” he revealed.

Throughout the project the main contractors Ascon and Dragados call on the services of specialist contractors. “You would have the likes of the earthworks contractor the pre-cast concrete suppliers, concrete suppliers, gravel suppliers as well as the likes of the Swiss company that pushed the bridge into place,” Ian affirmed.

Subject to the vagaries of the Irish weather Ian is confident the project will be completed ahead of schedule.

The 12km route, which will form part of the Trans European Road Network (Euroroute E101), will edge the M1 motorway ever closer to the Border, will significantly reduce journey times and make an important contribution towards road safety.