Atkins is an award winning designer of roads and bridges
Project: N8/N25 Dunkettle Interchange Upgrade
Client: SIAC construction Limited
Atkins Role:
Atkins was responsible for the detailed design of the upgrade of Dunkettle Interchange and widening of the N25 dual carriageway. The design and build contract, valued at approximately €3M was awarded by Cork County Council to SIAC Construction Ltd.
The Dunkettle Interchange is located 4km from Cork City Centre at the intersection of the N25 and N8 National Primary Routes on the northern entrance to the Jack Lynch Tunnel
The scheme involved widening and signalisation of the Dunkettle Interchange and widening 3km of the existing N25 from dual two to dual three between Dunkettle Interchange and Little Island Interchange.
Three new sign gantries were provided on the approach to Dunkettle and Little Island Interchanges. The sign gantries used were single span steel portal frames with reinforced concrete pad footings. To provide a more economic solution, two sign gantries were combined into a single structure spanning approximately 39m across both carriageways of the N25.
MOVA technology was employed for traffic signals on the Interchange to cater for variable traffic flow patterns throughout the day. The system can cater for unpredictable traffic flow sometimes experienced at this interchange, for example, during tunnel closures.
Portal Signal gantries were used for the approaches to the interchange to improve the visibility of the signals. This was the first time one of these signal gantries was used on a project in Ireland. The gantries were supplied from the Netherlands where they have been used successfully at major signalized junctions.
The main constraint during the project was the maintenance of traffic flows at the interchange, which required extensive traffic management. Signal and sign gantries were erected during overnight road closures for safety reasons.
