Tetra Tech delivered multidisciplinary engineering consultancy for the 4.3 km bypass of the N59 around Moycullen, improving safety and reducing traffic through the village and crossing environmentally sensitive areas.
The N59 Moycullen Bypass scheme is an offline realignment of the existing N59 which extends from Galway City to Connemara aiming to address traffic issues and their environmental and safety impacts.
The project is located 13km outside Galway City and extends from approximately 1.5km north-west of Moycullen to 2km to the south-east. It involved the construction of a 4.3km Type 1 single carriageway road bypassing the village of Moycullen, with a roundabout junction at each end offering connections back to Moycullen village.
Challenge
The overall objective of the N59 Moycullen Bypass scheme was to address the traffic problems on the N59 through Moycullen, and the environmental and safety impacts of those traffic problems.
The significant volume of through traffic increased community severance, noise and emissions, and reduced road safety within the village.
The previous route was poorly aligned and narrow in many places with frequent junctions and accesses passing through highly scenic and environmentally sensitive areas. The road also acted as a barrier between the residents located south of its alignment and the community facilities located to the north of the village. Pedestrians and cyclists that used the route were exposed to particular safety risks due to its inadequacies.
There were a number of constraints within the study area, principally the built-up area of Moycullen village, the lakes to the east, the higher ground to the west, and the various environmental and heritage designated sites. A combination of these constraints limited the viable route options for a bypass scheme.
Solution
Our multi-disciplinary engineering consultancy services included detailed design, advanced and main works contracts procurement, construction supervision, contract administration and PSDP for the scheme on behalf of Galway County Council.
Key elements of the scheme include:
- 2 at-grade roundabouts on the N59
- 8 bridge structures (road, river, canal and underpasses)
- 3.5km of local road improvements/realignments
- 1.7km farm/accommodation roads
The development has significantly improved pedestrian and cyclist safety in Moycullen. An average of 15,000 to 16,000 vehicles travelled through the village during our mid-2019 traffic count. The bypass is forecast to result in a 74% reduction in traffic flow in the village north of the signalised junction and a 53% reduction south of the junction.
At a glance
Client
Galway County Council
Location
Co. Galway, Ireland
Services
Advanced and main works contract procurement, construction supervision, contract administration, detailed design, project supervisor design process (PSDP)
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.