2008:1313 - Foreshore, Greystones, Wicklow

Assessment and systematic recording of the Gap Bridge and surrounding environment was undertaken as part of the Greystones Harbour Development Project. The Gap Bridge is located along the upper foreshore of the North Beach, where it is exposed on top of a heavily eroded sandy cliff, c. 900m north-east of the Greystones Harbour area. The structure crosses a small stream, known as the Water of Rathdown, which forms the townland boundary between Rathdown Upper, to the north, and Rathdown Lower, to the south. A stony costal strip (the North Beach), delineated by a heavily eroded sandy cliff, bounds the eastern limit of both townlands. The bridge lies adjacent to the historic site of Rathdown Castle (WW008–1101–1102).
The bridge structure is of late 19th-century date and represents a second railway bridge construction at the site, following the collapse of the adjacent Ennis Bridge. The standing elements of the Gap Bridge were considered of an unstable nature and access to the structure and the adjoining cliff faces was limited. The assessment endeavoured to provide as detailed a record of the structure as possible given this health and safety constraint.
A Topcon differential GPS and a reflector-less Leica Total Station, supplemented by photographic and hand-drawn elements, was employed to produce an overall plan of the structure and its outlying debris field. Two elevation drawings were made showing the eastern and western bridge façades. A series of datum points were affixed to the structure and position-fixed using the Total Station. This allowed accurate scaling of the photomosaic and digitised elevations. Detailed plan and elevation drawings were produced, constituting a comprehensive record of the existing structure. The assessment work was carried out between 13 and 14 March 2008.