The new Killaloe Bypass, Shannon Bridge and R494 Improvements Scheme started on site in late 2022.
The scheme incorporates an approximate 6km length of new road and upgrade to the existing R464. Designed to provide traffic relief to the town of Killaloe the scheme also included two new piled structures which included a new rail bridge located at the southern end of the project, and a major new bridge across the River Shannon immediately south of Killaloe.
P J Edwards & Co Ltd were appointed by John Sisk & Son to deliver the piled solutions for both of these structures and started work on the first large Shannon Bridge Crossing in December 2023.
Shannon Bridge
The piling scope on Shannon Bridge included both land based piling work, and also a number of bridge supports required to be piled from marine craft at three pier locations within the river itself.
The overall scope was for 40no. 900mm diameter land based piles to depths of 37.5m, and 30no. 900mm diameter permanently cased marine piles drilled to depths of 30m. All piles were designed to found into a hard underlying bedrock with sockets lengths up to 9m.
Both elements of work proved very challenging with the land based piling requiring 50% of the piles to be installed at a 1 in 6 rake which necessitated the use of full length temporary 1000mm diameter segmental casing. To add to the challenge, the piles were designed with full length cages, fitted with sonic logging ducts, and needed to be concreted under water using tremie techniques.
The land based work did however give P J Edwards opportunity to deploy their new Mait HR420-800 drilling rig which at 135t working weight also boasts an impressive 42Tm available drilling torque combined with a further 80Tm torque available via a torque multiplier proving critical for casing installation and extraction.
For the marine based work one of our smaller 85t Mait HR260 rigs was utilised working from a bespoke jack up barge, serviced by a 100t crawler crane mounted on a separate spud leg barge.
The marine support plant was supplied by Sisk and required detailed joint planning, combined with a close working relationship on site, to ensure the marine works were delivered to the correct quality, budget, and importantly on time as the works were programmed to be carried out in a narrow time window to mitigate the impact on the sensitive ecological river environment.
As the marine piles extended up to water level they also required the installation of a permanent thick walled 914mm o/d steel casing which varied in length from 14m to 27m. The casings were delivered to site in sections up to 12m long before being welded by P J Edwards own welding team, and then pitched and driven in single fabricated lengths.
Railway Bridge
The scope of work for the railway bridge incorporated 128no. 450mm piles up to 15m in depth required for two abutments either side of a live railway.