Mary Elmes Bridge, Cork City
Structural Steel Design Awards 2020 - Commendation
In September 2016, a design competition was held for a pedestrian bridge crossing the River Lee, located in the heart of Cork city. The requirements were for a single span, sympathetic with the local city architecture while providing a minimum walking width of 4.5m, unimpeded views of the river while having minimal impact on the existing flooding regime.
The initial concept developed by the winning design team focused on a structure with a central spine beam, aiming to conceal the structural depth within the railing height. With a 66m span between quays, it was identified early in the design phase that a significant depth was required; a 1.8m-deep beam at midspan was suggested with the beam going to 2.2m-deep at the supports.
Transitioning the central spine beam from below to above the deck along the span introduced a small arch effect which, along with fully integral abutments, resulted in increased stiffness in bending, thus increasing the slender appearance of the bridge. To further increase the structural efficiency, the pedestrian walkway is integrated into the structural system with the position of the walkway favourable relative to the position of the neutral axis of the main spine beam at both midspan and at supports.
Combining the shallow slender arch with transparent mesh parapets delivers an understated but visually appealing design with uninterrupted views of the river and cityscape and embedded benches on either side of the central beam has resulted in the bridge becoming part of the urban realm. The widening at midspan creates a natural meeting point.
Extensive modelling was used to optimise the geometry of the bridge and deliver the most efficient shape to minimise the amount of steel required. The 3D models of this lightweight structure were also used for virtual design reviews to ensure full alignment and coordination throughout the project.
The bridge was fabricated offsite in nine sections before assemblage at a shipyard downriver from its eventual home. In May 2019, the completed structure was transported up the River Lee on a custom-made barge. It was then lifted into position by cranes located on each quay during an overnight road closure in a tandem lift of 160 tonnes.
Honouring Mary Elmes, known as Ireland’s Oskar Schindler, this transformative bridge link is part of Cork’s drive to become a more accessible, sustainable city and is a sympathetic companion to the surrounding quays, buildings and urban realm.
|Client||Cork City Council|
The elegant and deceptively simple design of this bridge has turned a new pedestrian and cycle city centre river crossing into something of a destination in its own right. In addition to the celebrated appearance, particularly at night, the judges were impressed by the daring success of the barge delivery and overnight installation of the bridge.