Mizen Head Footbridge (2010) Cork
The Mizen Head Footbridge is a reinforced concrete through-arch structure which provides access to a lighthouse at the tip of Mizen Head in the south west of County Cork. The current bridge was constructed during 2009 and 2010 to replace an older bridge which had existed for almost a century.
The Commissioners of Irish Lights held a design competition in the early 1900s for a crossing to the lighthouse on the island of Cloghán. The winning design by a Mr. Ridley from London was for a reinforced concrete structure comprising a pedestrian deck suspended between a pair of parabolic rib arches anchored 45m (147 ft) above the gorge. The bridge span was 52m (170 ft) and the arches flared from a width of 3.7m (12 ft) at either side to 1.6m (5.25 ft) at the central section where the ribs intersected the deck.
The bridge was built by Alfred Thorne & Sons of London and was completed in 1909 at a cost of £1,272.
Despite its exposed location and harsh environment the bridge survived in good condition due to regular maintenance and repainting. However, inspections in the early 2000s indicated defects that necessitated refurbishment or replacement of the bridge.
The chosen option was to replace the bridge with an almost identical replica and the contract to build it was awarded to Irishenco. The new bridge was designed as a two-pinned arch constructed in reinforced concrete using stainless steel reinforcement and it differs from the original only in the width of the deck which is 70cm (2.3 ft) wider.
The difference in width allowed the construction of the rib arches outside the existing bridge using the old ribs as supporting falsework. As the new bridge progressed the older one was demolished. Construction work took place between October 2009 and December 2010 with the official opening taking place on 17th March 2011.
Links: Wikipedia | Application for engineering project of the year 2011 (PDF) | Engineer’s Ireland Design & Construction info (PDF)