Project Summary
Coffey, as part of a three-way Joint Venture, delivered a major section of the M7 Nenagh–Limerick Motorway scheme — a critical upgrade to Ireland’s national road network. The works included 28 km of new motorway-standard dual carriageway, the widening of 10 km of the Nenagh Bypass, and 2 km of single carriageway to connect the M7 to the N7 at Birdhill. The project also featured the design and construction of major grade-separated junctions, multiple structures, and extensive drainage and environmental protection measures. The scheme has significantly improved connectivity between Dublin and Limerick, reduced journey times, and enhanced road safety for all users.
Project Description
The M7 project was one of the most complex road infrastructure schemes undertaken in Ireland, comprising 38 km of motorway works, including the upgrade of the existing Nenagh Bypass and the delivery of new links to the N7. Coffey was responsible for constructing 12 km of the mainline, including the high-traffic Anacotty Interchange and numerous side-road crossings, while maintaining full traffic flows with Average Annual Daily Traffic (AADT) volumes exceeding 20,000 vehicles.
The scope included the construction of three key bridges, extensive earthworks, drainage systems, and environmental mitigation works. Significant engineering challenges were encountered, including the construction of over 7 km of road through soft bogland, crossings of rivers, rail lines, and live roads, and managing over 3.2 million cubic metres of material.
Innovative engineering solutions were deployed, such as over 8,000 precast piles, geotextile-reinforced stone platforms, tyre bales for floating roads, vertical drains, and surcharge loading with settlement monitoring. These measures ensured stability and longevity in challenging ground conditions.
Scope of Works
The works included:
- Construction of 28 km of new dual carriageway and 2 km of single carriageway, plus 10 km of upgraded Nenagh Bypass.
- Four major grade-separated junctions at Newport, Coolderry, Carrigatogher, and Knockalton, with associated slip roads and realigned national, regional, and local roads.
- 26 principal structures, including a 140 m viaduct at Kilmastulla, plus numerous minor structures, chambers, and ducting works.
- Three bridges constructed by Coffey:
o Two reinforced earth road overbridges, 35 m double spans, 5 m high.
o One Irish Rail overbridge, 23 m double span, 3 m high. - Extensive earthworks including 2 million m³ of rock excavation by blasting, 900,000 m³ of material from an on-site quarry, and 400,000 m³ bog excavation and replacement.
- Comprehensive drainage network with 54 km of filter drains, 46 km of carrier drains, 35 km of fin drains, 40 km of open drains, and 17 treatment ponds.
- Utilities diversions, fencing, safety barriers, signage, lighting, and landscaping.
Technical Highlights
- 38 km of motorway delivered, comprising 28 km of new dual carriageway and 10 km upgrade of the Nenagh Bypass.
- 32 major bridge structures completed, including 10 overbridges, 17 underbridges, 2 rail bridges, and 3 river bridges.
- Over 8,000 precast piles installed, up to 36 m deep, with two large retaining walls.
- 3.5 km of motorway and 4 km of access roads built through bogs using tyre bales.
- 49 attenuation ponds and 6 storm tanks installed, providing a combined capacity of 85,000 m³.
- 3.2 million m³ of material excavated, including 2 million m³ of rock.
- On-site quarry produced 900,000 m³ of road-building materials.
- 600,000 tonnes of asphalt and 120,000 m³ of cement-bound material laid.
- Over 100 km of piped drainage and 95 culverts completed.
- More than 30 traffic phases implemented to maintain live traffic flows.
Added Value
- Maintained live traffic flows with AADT of 20,000 at key interchanges.
- Optimised bridge construction using reinforced earth walls for efficiency and reduced programme duration.
- Maximised use of on-site quarry materials to reduce haulage and environmental impact.
- Used innovative ground engineering techniques to deliver stable roads through soft bogland.
- Delivered complex rail and river crossings within tight programme constraints.
- Coordinated traffic management across more than 30 phases without significant disruption.
Environmental, Safety or Community Measures
- Extensive drainage and attenuation systems to protect the River Shannon catchment.
- Construction phase environmental controls, including sediment management, water quality monitoring, and river protection measures.
- Landscaping and habitat reinstatement along the route.
- Ongoing stakeholder engagement with Irish Rail, local authorities, and community representatives to minimise disruption.
To learn more about Coffey’s work in active travel and urban infrastructure, or to discuss future opportunities, please contact us at 091 844356 or info@coffeygroup.com.
