The Killaloe bypass, Shannon bridge crossing, and R494 improvement scheme stands as a landmark achievement in Irish civil engineering, delivered by Sisk, for Clare County Council. This transformative €88m infrastructure project includes Ireland’s first new vehicular bridge across the River Shannon in more than 30 years – the Brian Ború bridge.

Significant focal point

Although the bridge is a significant focal point, there were two other aspects of the project, a 2km bypass of Killaloe and 3.3km of improvements to the R494, from Birdhill to Ballina.

Completed after just two-and-a-half years of construction, the scheme showcases Sisk’s engineering expertise in delivering complex infrastructure safely, efficiently, and sustainably. The project provides greatly improved traffic flow, safety, and regional connectivity.

Sisk managed significant engineering and environmental challenges throughout with detailed planning and innovation. The works required 393,000 cubic metres of cut and 323,000 cubic metres of fill, the construction of 22 structures, and extensive geotechnical operations within a sensitive river environment.

At the heart of the scheme, the Brian Ború bridge extends 207 metres in length and 16.6 metres in width, supported by six steel arches and 70 bored piles reaching depths of up to 36.5 metres.

Construction involved marine-based techniques including the use of barges and temporary causeways, all undertaken under strict environmental controls due to the area’s designation as a special area of conservation.

Sisk introduced several innovative engineering solutions to optimise efficiency and minimise risk, such as stitching precast pile caps in-river to reduce heavy lifting, fabricating and welding steel pile casings on land before installing them as single units ensuring programme certainty and deploying 4D digital modelling to enhance sequencing, coordination, and risk management. These engineering advancements not only accelerated delivery but also reduced environmental impact and enhanced overall construction safety.

Sustainability was embedded throughout the project. Sisk achieved major carbon reductions using hydro-treated vegetable oil (HVO) fuel and concrete mixes containing 50% ground granulated blast-furnace slag (GGBS). The project design team RPS included design optimisations, including integral pier connections and the removal of bearings and post-tensioning, reduced embodied carbon and long-term maintenance demands.

Environmental protection was a key focus, with continuous collaboration with Inland Fisheries Ireland to safeguard aquatic habitats. Measures included species translocation, invasive species management, and continuous water quality monitoring, while construction was carefully scheduled outside fish spawning periods.

Vegetated reinforced soil slope

Biodegradable hydraulic oils and silt curtains were employed to protect the river environment, and a carbon-intensive piled slab was replaced with a vegetated reinforced soil slope to provide a low-carbon solution for peat management.

More than 800,000 man hours were worked on the project with an industry-leading safety record, underpinned by robust safety management, emergency drills, and close collaboration with the Irish Coast Guard. The project was delivered ahead of schedule, with the Killaloe bypass section completed in December 2024, full completion achieved in March 2025, and the official opening taking place in May 2025.

The successful delivery of the Killaloe bypass and Brian Ború bridge demonstrates Sisk’s capability in managing technically demanding, environmentally sensitive, and community-focused infrastructure projects.

It stands as a showcase of sustainable engineering excellence that strengthens regional connectivity, reduces congestion, and supports long-term economic and environmental resilience across Ireland’s midwest region.