Transport Infrastructure Ireland had a programme to create better connections throughout southern Ireland. Part of the programme included a new 14-km-long dual-carriageway allowing traffic on the N25 to bypass New Ross in County Wexford. The bypass included a 900m three-tower bridge over the river Barrow.
The N25 is an extremely busy road connecting Cork City and Rosslare Europort and traffic often tailbacks causing commuters long delays. In many cases, these tailbacks have been known to add an extra 20-60 minutes to a vehicle’s journey.
The new bridge is 900 metres in length, making it Ireland’s longest bridge (in comparison, the bridge in Wexford Town is 590 metres in length). Murphy were brought on board by the BAM/Dragados joint venture who constructed the Barrow Bridge to provide the piling foundations.
The piles are the deepest rotary-bored piles in Ireland at 35m deep. At the time of tender and construction, Murphy were the only company in Ireland with the capabilities to deliver the required piling.
The piles for Barrow Bridge are the deepest ever constructed in Ireland at the time. As this was the first time Murphy Ground Engineering had been commissioned to construct such deep piles in Ireland it was always going to be a challenge. A challenge that the expert and experienced team were excited to take on, fully confident in their ability to achieve something special in Irish ground engineering. The same teams had previously constructed similar depth piles in the UK.
The Murphy team used their innovative cage end plates due to the length of depth of the piles. With such large piles it was a worry that cages would become stuck in the casings when removing them. To ensure the cage would not lift as the operator extracted the temporary casing, a steel plate was attached to the bottom. From previous projects, Murphy had also learnt that at such deep lengths the steel cages became much less rigid. To combat this the diameter of the rebar was increased.
The team constructed the piles right next to the river. A one metre high barrier was erected alleviating both safety and environmental concerns.
So much plant in a small working area meant that strong collaboration was required as well as meticulously designed movement plans to make sure that worked flowed slickly and safely. Appropriately trained banksman were present at all times with fully trained and experienced operatives working on project. Plant was shared with BAM/Dragados JV to reduce the amount of plant on site.
Murphy operated two rigs on site (BAUER BG28 and BAUER BG26). A crane was also used to lift the cages and allow the rigs to move on to the next pile – reducing the time of the programme.
During early negotiations, Murphy also recommended the use of 1200mm diameter piles as opposed to 900mm. Increasing the diameter of the piles meant there needed to be less of them, saving material cost and time. Recommendations on diameter of piles saved client 20% on original budget.
For the team on site this was a straight forward programme given their combined experience and knowledge. They were aided by systems of works and quality equipment that allowed them to carry out the project without any incident or issue.
The client was responsible for design of the permanent structures, however, Byrne Looby in partnership with Murphy was responsible for the design of the temporary piers.
Safety platforms; built in elevated platform giving operatives a safe point to stand access the sides of the piling rig
The steel fab shop in Newbridge created the steel cages to transport the tremie pipe sections. The pipes sit at an angle which makes them easier to clean after use.
The piles required the largest dynamic test ever completed in Ireland on a bored pile, (15,567kN) and as such BAM provided Murphy with the hammer necessary to complete such a test. Sonic logging tubes were placed in a number of piles, as selected by the client. These are used to inspect the integrity of the pile all the way to the toe. All testing was carried out by Lloyd Acoustics.
The Murphy Ground Engineering team delivers a range of piling and geotechnical services including in-house pile design, value engineering and bespoke technical solutions throughout the UK and Ireland. We also offer leading Building Information Modelling (BIM) capabilities, investing in digital solutions for new rigs, remote diagnostics and computer monitoring systems of rotary pile construction.