The 158 km Dublin to Waterford inter-urban route has seen significant improvements since the 1990s with the construction of the M9/M7 motorway from Kilcullen in County Kildare to the Dublin peripheral motorway. The remaining length of N9/N10 between Kilcullen and Waterford City on the South East coast is currently being upgraded to motorway standard in four separate phases and these are from North to South:
Phase 3 – Kilcullen to Carlow (27.5 km)
- Phase 1 – Carlow Bypass (18.5 km)
- Phase 4 – Knocktopher to Powerstown (40.0 km)
- Phase 2 – Knocktopher to Waterford (24.0 km)
Phase 3 comprises a 27.5 km length of high standard dual carriageway/motorway (N9), with an 11.2 km length of single carriageway spur to the town of Athy.There are 41 principal structures on the scheme which were produced to a very tight programme to tie in with the contractor’s earthworks programme. The structures were designed using pre-cast and prestressed beams on in-situ abutments. Where suitable, reinforced earth abutments were used. The choice of construction method reflected the need for speedy progress, the repetition of detail and also to minimise disruption from earthworks movements along the route.
The over bridges are mainly two span with a central pier contained within the 2.6 m median. The standard cross section for this road included a concrete median barrier with bifurcation around the central pier necessitating the widening of the road footprint in the vicinity of the bridges. However for this project, the team developed a feature that incorporates the central pier within the width of the concrete barrier. The pier is also designed for collision loading. This design feature removes the bifurcation and wider pavement resulting in significant cost savings.
The contractor Roadbridge, together with Fehily Timoney Gifford (FTG), a long-standing joint venture between Irish consultant Fehily Timoney & Co and UK- based Gifford, spent the summer of 2007 tendering for the scheme which was procured as a design and build project incorporating the first use of the new, and very onerous, Form of Public Works Contracts. Gifford India Pvt. Ltd. (Now part of Ramboll) was entrusted with detailed design of 2 span integral bridges by Gifford UK (Now Ramboll UK).
Specific services rendered include the following:
- Carried out the detailed design of 7 2-span integral over bridges using SAM-LEAP software on DMRB standards along with BS:5400 guidelines and NRA stipulations.
- Category – II checking of 1 no. of 2 span integral bridge i.e S25.