The design and construction of the cross-harbour road and rail links, Belfast

摘要

The paper describes the principal features of the design and construction of the elevated road and rail links in central Belfast, Northern Ireland. The project was the subject of a three-stage design and construction competition. This paper outlines the evolution of the winning design and details the most significant elements of that design. The road link comprised elevated dual two to four lane carriageways over a total length of 950 m, with a separate parallel rail link of 1500 m. Both structures included a river crossing of 165 m. The overall geometry involved significantly curved alignments. For the foundations, the design and installation of major cofferdams and steel-tube piles in the river are outlined, together with the installation of 2200 precast concrete and continuous flight auger piles on land. The bridge decks are of concrete box construction, precast in match-cast segments in a purpose-built three-cell factory. The land spans comprised 828 segments 2.2 m deep weighing between 55 t (road) and 75 t (rail), while the river spans comprised 230 segments varying between 2.2 and 5 m deep weighing up to 95 t. The balanced cantilever erection techniques using a 230 t crawler crane on land and a similar crane strapped to the deck of a flat-top barge in the river are described, together with the dimensional controls exercised during fabrication and subsequent erection of the decks.