Tetra Tech acted as Contractor’s Designer for the €250 million 25.5 km dual carriageway between Westport and Turlough, enabling improved regional connectivity in County Mayo.
The N5 Westport to Turlough Road is a 25.5km roadway that consists of 20.3km of Type 2 dual carriageway and 5.2km of single carriageway. It runs from northwest of Westport at Deerpark East to the townland of Ballyneggin near Turlough where it connects with the existing N5.
We acted as Contractor’s Designer on this €250 million scheme, which represents the largest ever Government investment in County Mayo.
Challenge
The previous route suffered from poor alignment and a deficient cross-sectional width, with many private and commercial developments across the route.
The route also had a poor road safety record and was reported as having a collision rating twice above the national average.
The high traffic volumes and high number of collisions led to a number of instances where the route was difficult to access for long periods of time. This resulted in varying journey times across the route, reducing productivity and efficiency in the area.
Acting as a connector between the West and Midlands of Ireland, the previous state of the infrastructure was inhibiting the connectivity of the regions and dampening economic growth.
Solution
By working collaboratively with our contractor partner; Wills BAM JV, we successfully delivered this significant project that will positively impact the region for generations to come, improving both road safety and journey times between two of Mayo’s largest towns and enhancing economic development.
Efficiently diverting national traffic away from the town centre of both Castlebar and Westport, whilst retaining sufficient access for local traffic to the towns will also enable Castlebar and Westport to focus on sustainable transport policies, creating shorter commutes and developing safe pedestrian routes for the benefit of both locals and tourists.
The overall project also included:
- 2 compact grade separated junctions, including overbridges
- 6 roundabouts
- 59 at grade priority junctions
- 27 structures (2 rail bridges, 11 overbridges, 3 underbridges and 11 underpasses)
- Associated earthworks, drainage, landscaping
- Realignment of existing roads, accommodation tracks, diversion of services and ancillary works
At a glance
Client
Wills BAM JV
Location
Co. Mayo, Ireland
Services
Contractor’s designer, Project Supervisor Design Process (PSDP) site supervision
The project featured in this article was undertaken by RPS, A Tetra Tech Company and originally published on RPSgroup.com. In March 2026 RPS rebranded to Tetra Tech.