Dublin City Council is planning to build a new bridge over the River Liffey in Dublin City Centre, just downstream of O’Connell Bridge. The bridge, which forms part of the Transport 21 Plan, will carry buses and the LUAS at this critical location across the Liffey. It will have cycleways and generous footpaths that will open Marlborough Street and Hawkins Street to greater footfall, prospective development and create a new north-south link from Abbey Street to Pearse Street.
The bridge will have an elegant contemporary design. It will be a slender, single span, smooth concrete structure, with the underside of the bridge being designed to be as high above the water as possible so that river traffic is not impeded. An image of the proposed development is available from the Press Office Tel: 01 2222170. Details are also posted on the Council website www.dublincity.ie under 'roads and traffic' projects.
Construction is due to commence in late 2009. The project is funded under the Transport 21 programme and the initial cost estimate is €15M which includes additional works required to the roadways on either side of the bridge.
Notes to the Editor:
Dublin City Council appointed the team of Roughan & O’Donovan Consulting Engineers and Seán Harrington Architects in May 2008 to design the bridge. Both have a proven track record of bridge design; Roughan O’Donovan was the engineer for the Taney LUAS Bridge in Dundrum as well as the M1 Boyne Bridge at Drogheda, amongst others, and projects by Seán Harrington include the Dublin Millennium Bridge. The team is complemented by the Conservation Architect David Slattery, to ensure that the historic quay walls are properly conserved, and to advise on other matters relating to the historic and important setting.
The bridge will incorporate flood protection walls, which double up as public seating and planters for flower displays. The pedestrian walk-ways are wide, and the bridge is gently sloping to facilitate easy crossing for all, including those in wheelchairs and with children’s buggies. Balustrading is visually transparent, allowing a good view of the river from the bridge and to help give the new structure an elegant and slender profile when seen from the quays and the adjacent bridges.
The use of structural concrete provides aesthetic and geometrical flexibility, robustness and longevity. The underside of the bridge has a shallow curve, which tightens before reaching the quay walls to form the abutments. This curvature resolves the bridge structurally and visually. Below the bridge, the abutments form a double-bulge on plan allowing the river to flow around them easily and limiting the protrusion of the abutment into the river. As the abutments rise, the curve gradually flattens and morphs into the gentle single-curve under-belly of the bridge.
High-strength concrete in the bridge deck will minimise structural thickness and the deck will be post-tensioned, pre-stressed construction. The location of the abutments in the river will minimise the impact on the quays – and therefore traffic – during construction. It is envisaged that the deck will consist of precast shells which will minimise construction time and contamination risks to the river environment (by acting as permanent formwork).