Design of the Dubai Metro light rail viaducts—superstructure

The Dubai Metro light rail scheme is a flagship project in the United Arab Emirates. It is currently one of the largest civil engineering projects under construction and, when completed, it will be the longest fully automated rail system in the world. The first phase of the rail system is due to be opened in September 2009 and will include over 42 km of precast concrete viaduct. The majority of the viaduct utilises a slender precast segmental post-tensioned concrete U-shaped trough form for its construction, with a width of 10 m, a total depth of 2·04 m and span lengths up to 44 m. The slender deck slab and profiled edge beams result in both an economic and aesthetically pleasing structure which has been rapidly constructed while being suitable for the harsh environment of the Middle East. The wide U-shape of the deck is unusual for concrete bridges and presented a number of challenges, including complex three-dimensional and dynamic behaviour. This paper discusses the design and construction of the viaduct superstructure. It presents the structural arrangement and design of the precast segmental U-shaped trough deck, describing the challenges encountered in the detailed design phase of the project.