Mulroy Bay Bridge

Appointed by Donegal County Council, RPS worked on Mulroy Bay Bridge from its inception, undertaking the feasibility study, preliminary and detailed design work, and environmental impact statement. The task was to deliver a bridge with a main span of 100 metres with approach spans of 66m and 54m (340m total length) with 20 metres clearance allowed for shipping in the estuary.

The works were undertaken in extremely sensitive waters (Grade A) in a remote location at the northern tip of Ireland.  Our team delivered the project through planning and design phases and then supervised the construction of the bridge. The project was awarded the LAMA Award in 2010 for the Best Public Infrastructure Project in Ireland

Key details

Project name

Mulroy Bay Bridge


Donegal County Council


Fanad, County Donegal, Ireland

Services provided

  • EIS
  • Public consultation
  • Preliminary design and technical approval
  • Detailed design
  • Procurement
  • Construction supervision
  • Contract administration and employer’s representative role


The remote location of Mulroy bay and its importance as an area of high marine ecological interest added a layer of complexity to this project.

Mulroy Bay lies on the north coast of County Donegal between the Fanad and Rosguill Peninsulas. The remote marine inlet is approximately 12 km long. A trip between the two points in each peninsula at the bridge site involves a journey of 50km and a travel time of over two hours.

Sunset view of Mulroy Bay Bridge during construction


The project included co-ordination of specialist subconsultants for particular environmental issues. Given the location, impacts on marine ecology and water flow were a key concern and involved the use of specialist consultants for marine surveys and mathematical modelling.  Close liaison with our design team enabled mitigation of environmental impacts to be incorporated within the design. Extensive public consultation with local residents and commercial operators was undertaken throughout the development.

The project involved the construction of a high level multi-span bridge across Mulroy Bay and associated approach roads and pedestrian facilities. The bridge is approximately 340m long, comprising of 5 spans with a main span of 100 metres. The deck is a post tensioned reinforced concrete box girder section, constructed by the balanced cantilever construction method. The bridge spans onto reinforced concrete piers and  reinforced earth abutments. The piers are founded on pile caps over water. The approach roads are approximately 2.6 km in length, comprised a two lane single carriageway with 3.5m lane widths and footpaths each side.

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