The €102M (£85M) project to connect communities north and south of the Irish border with the Narrow Water Bridge has commenced piling works.

The new cable-stayed rolling bascule bridge will connect the Cooley Peninsula in County Louth in the Republic of Ireland with the Mourne in County Down in Northern Ireland, as well as the northern and southern shores of Carlingford Lough.

The Narrow Water Bridge features two primary adjoining structures, a 138.4m fixed cable-stayed structure and a 56.8m cable-stayed movable bridge spanning the navigable channel of the Newry River.

NCE sister title Ground Engineering reported that last month main contractor Bam announced that piling works were progressing on the project. While Bam is self-executing some of the minor earthworks and groundworks, the permanent and temporary piling contractor is Quinn Piling.

The scheme was designed by Roughan O’Donovan, with support from Hardesty & Hanover.

Other companies involved in the project include Aelterman as the bridge structural steel fabricator; Demako for mechanical, electrical, instrumentation, control and automation (Meica) works; VSL for the stay cables; Bridge Construction Consulting for reinforced concrete works; and S&E Contracts for the control building.

Bam officially began construction of the project in June 2024. The scheme is funded by the Irish Government’s Shared Island initiative.

Piling scope

Bam construction director William Diver told GE that the project includes a significant piling scope:

“In addition, we have significant temporary works piling to facilitate the installation of the bridge,” Diver added. “This includes 36, 914mm diameter steel piles with rock sockets installed using the bored methodology, with marine piling undertaken from jack-up barge, required for the installation of the fixed span, and 24, 914mm diameter steel piles required for the installation of the bascule span.”

South abutment rotary bored piles

Geology

Along the Newry River, the project team has identified alluvial materials, including gravels and boulders, deposited by the flowing water.

“These are generally thin deposits of silts and gravels, up to a maximum thickness of between 1.5m and 3m, where a matrix of cobbles and boulders are present,” Diver explained. “The depth of soft silty alluvium proven was determined to a maximum of 1.3m at the northern mudflats but is generally 0.5m or less across the majority of the riverbed.”

He added: “The site is underlain solely by sedimentary rock of the Inniskeen Formation, which is composed of turbiditic greywacke sandstones and minor amounts of shale or mudstones (Silurian deposits). This formation is thought to be medium to thickly bedded. There is characteristically high micaceous and biotite content in this formation. These minerals readily decompose if exposed to the environment so the sandstone should therefore be susceptible to weathering.”

He noted that the team has found the rock to be of better quality than indicated by the site investigation. However, the piling works have largely stuck to the design as other constraints have defined the rock socket lengths.

“For example, the Ruukki pile length is defined by the base level of the bascule chamber with rock sockets typically over 7m,” he said.

The biggest challenge created by the ground conditions has been the optimisation of the rock socket length across all the piling works, adding up to more than 1km.

“We have worked closely with the employer’s designer, Roughan O’Donovan to ensure rock socket lengths have been optimised in so far as possible,” Diver noted.

Bascule abutment Ruukki piling

Completion

Construction on the Narrow Water Bridge is expected to be completed by late 2027.

Once opened in 2028, it will connect the A2 Newry to Warrenpoint dual carriageway in Northern Ireland with the R173 at Omeath in the Republic of Ireland. The bridge will accommodate vehicular, cycle and pedestrian traffic, as well as being able to open to allow for the passage of ships through and on to the Newry Canal.

Artist impression of completed Narrow Water Bridge

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