Dubai Metro footbridge design

The Dubai Metro light-rail scheme is a flagship project in the United Arab Emirates and the longest fully automated rail system in the world. The first line of the rail system was opened in September 2009 with a second line due for completion in 2010. These first two lines include 35 elevated stations along their combined 76 km length. This paper describes the design and construction of the steel truss footbridges developed as part of the station context planning work for all of the elevated stations. The footbridges are all fully enclosed, air-conditioned corridors with the widths of many dictated by the provision of automated walkways. A key aspect to the footbridge design concept was to develop a modular system that could be rapidly designed for scores of differing span arrangements to be suitable for each unique location. Several of the footbridge truss elements comprised structural hollow sections, and the new rules in Eurocode 3 were adopted to design many of the connections between such members. With simply supported spans up to 45 m long and external cladding creating irregular shaped cross-sections, wind tunnel testing was required to demonstrate aerodynamic stability of the footbridges. Several erection methods were also considered to minimise the installation time of completed footbridge spans over the major Dubai highways, and the pre-camber and deflection analysis associated with the methods adopted for lifting were also important aspects considered in the design. Other critical design issues resolved included the design of fillet-welded connections in place of full-strength full-penetration butt welds and the design of several special spans for connecting into non-standard stations and entrance structures.