Client: Tarmac - Walls JV
Contractors Tarmac Walls JV utilised RMD Kwikform's vast skills and experience on the tunnel and open section elements of the river crossing of the River Lee in Cork, Ireland.
The Lee tunnel was the first immersed tube tunnel to be built in Ireland, and only one of three in the British Isles. The tunnel is just over 1km long, including 610m of box section tunnel elements, an open section on the north side, and in-situ finished approaches.
Each box section measures approximately 24m wide x 8.5m high x 122m long and comprosed of two 9.8mm wide dual lane traffic bores and a 1.35m wide twin walled central bore for services and emergency access.
The 1200mm thick base slab was cast first using RMD Kwikform's Mini Slim Soldiers, with timber panels and kickers. This was followed by the 500mm thick central walls. These required panels of Superslim Soldiers and steel channel walers, which were crane handled into position.
The outer walls and roof were cast together in a single operation in six nominal 21m lengths using special travelling formwork that can be struck inside the formed section, moved along to the next length and jacked up into position, all within a 72 hour cycle.
Each 1000m3 pour required approximately 1500m2 of formwork. The inside shutters for the outer walls were vertical steel section panels and Alform Beam walers, which were attached to the top slab of the special steel traveller, while the outer shutters were crane handled vertical steel section panels with Alform Beam or steel channel walers. 32mm diameter Rapid Ties allowed a working load of 270kN.
The open top boat units, measuring 42m wide x 122m long and up to 10m high were cast in two operations using standard RMD Kwikform formwork. All the elements and boat sections were cast from grade 40 ggbfs concrete, with reinforcement provided by 16 ñ 40mm diameter rebar.
The IR £70 million design and construction contract was awarded by the Cork Corporation on behalf of the National Roads Authority, who have received financial assistance from the Cohesion Fund of the European Union.