A6 Randalstown to Castledawson Dualling Scheme; A6 Randalstown to Castledawson Dualling Scheme;

A6 Randalstown to Castledawson Dualling, Northern Ireland

Leading the design of Northern Ireland’s roads to enhance connectivity

The A6 Randalstown Dualling Scheme represents a significant investment in Northern Ireland’s transport infrastructure. As an essential route used by 22,000 vehicles every day, enhancing regional connectivity by improving safety and reducing journey times on the existing road were the driving forces behind the design and construction of the scheme.

The new upgrades have transformed the route into a more sustainable and resilient dual carriageway that delivers long term benefits to road users and local residents. Connectivity between Belfast and the North West region of Northern Ireland has been improved, helping to facilitate further inward investment in the region.

Alongside our design JV partner, Roughan & O’Donovan, Arup has delivered a full range of civil engineering services, including construction supervision, to deliver the scheme on time and within budget. With significant project and site challenges, the team has focussed on minimising long-term maintenance costs for a road built through extensive soft ground areas and ensured the design integrates with existing structures to reduce the impacts of flooding and the overall carbon footprint of the scheme.

Project Summary

14.7km dual carriageway

22,000vehicles use the route per day

Supporting economic growth

The A6 Randalstown to Castledawson route is located to the North of Lough Neagh in Northern Ireland. The scheme provides the local area and the wider region with a high-quality transport link, set to deliver direct benefits to the community. Representing an investment of £189m, the scheme aims to strengthen the links between Belfast and the west of the province, allowing greater journey time reliability to support the economic development of the region.

The original roads through the area were single carriageway with many side roads and direct accesses onto and from the road. Our design has provided a new dual carriageway road with access now gained through grade separated junctions and the realignment of side roads to create a more dependable road network.

An early contractor involvement (ECI) team was appointed by the Department for Infrastructure, comprising Graham Farrans Construction JV with Arup and Roughan O’Donovan in joint venture to lead the engineering design. The ECI approach prioritised value for money and encouraged innovative thinking with high levels of collaboration.

A6 Randalstown to Castledawson Dualling Scheme A6 Randalstown to Castledawson Dualling Scheme
The new upgrades, which were delivered alongside live traffic, help create a more reliable and sustainable route in Northern Ireland. Image: © Graham Farrans JV

Minimising disruption

The scheme includes the design of 19 main structures including four pedestrian bridges to improve active travel infrastructure along the route. Our team ensured the greatest efficiencies were achieved across all structures. This included the four pedestrian structures and the mainline crossing of the Moyola River, which required design and construction of a new three-span bridge with live traffic on the adjacent pre-existing structure. Careful planning and collaboration with the contractor allowed upgrade works to the pre-existing bridge to be incorporated while minimising the impact on traffic through the works area. 

Our geotechnical design had to overcome the challenge of both deep soft ground and sensitive ecological areas in surrounding protected wetlands. Extensive ground improvements ensured that the long-term performance needs of the road were prioritised, while also taking into consideration the significant ecological constraints of the route. 

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