Roughan & O’Donovan, in 50:50 design joint venture, has delivered the detailed design for the 15km dual carriageway scheme between Castledawson and Randalstown on the A6 in Northern Ireland.
We also have a full-time designers site team working closely with the design offices and contracting team to monitor construction of the works.
The scheme involves the on-line/off-line improvement of the A6 trunk road from single carriageway to dual 2-lane carriageway (D2AP) between Randalstown and Toome and between Toome and the Castledawson roundabout.
We developed the detailed design in accordance with the Design Manual for Roads and Bridges and relevant technical memoranda, including Eurocodes and their UK National Annexes, as implemented in Northern Ireland.
Our technical outputs have been subject to the rigorous approvals procedures of the project manager, Transport Northern Ireland, the geotechnical advisor and Structures Technical Approval Authority (TAA) stakeholders.
A significant amount of topographical and geotechnical data informed the scheme design.
- 5 new compact grade separated junctions
- A new at-grade roundabout
- Various structures including 19 bridges, 11 overbridges, 2 footbridges, 4 underpasses, 2 riverbridges, and culverts
- Environmental mitigation works
- CEEQUAL contribution
- Ecological surveys and reporting
- Earthworks design
- On-line widening and dualling of existing single carriageway
- Health and safety duties
Soft ground to significant depth and environmental issues represent key project challenges.