Darlington upgrade project - pushing the boundaries in bridge design

The $620 million Darlington Upgrade Project (DUP) which is approximately 3.3 kilometres of the existing Main South Road is a critical piece of infrastructure forming part of the Adelaide North-South Transport Corridor. The development of a non-stop North-South Corridor, a major route for northbound and southbound traffic including freight vehicles running between Gawler and Old Noarlunga, is a direct result of a strategic objective to reduce Adelaide's urban road congestion. The project will provide a non-stop motorway from the Southern Expressway to north of Tonsley Boulevard. The project is being delivered jointly by Fulton Hogan Construction Pty Ltd and Laing O'Rourke Australia Construction Pty Ltd trading as Gateway South. The design delivery is a joint venture between Jacobs Group (Australia) Pty Ltd and Kellogg Brown and Root Pty Ltd and SMEC Australia Pty Limited trading as Gateway South Design Joint Venture (GSDJV). This paper will focus on the design of eight bridges comprised of a precast arch bridge spanning over the Sturt River and serves as on ramp to two-180m composite steel trough girder bridges over the existing Southern Expressway, four integral Super-T bridges providing grade separation for Flinders Drive, Sturt Road, Sutton Road-Mimosa Terrace and Tonsley Boulevard, and a 375m composite steel trough girder bridge as a grade separation of the Ayliffes Road interchange for northbound vehicles. The paper will also discuss the design challenges of the innovative construction approach adopted for the three long span steel trough girder bridges. The bridges were constructed on temporary towers off-line in an assembly yard of approximately 500m away from the final bridge position and then transported using the Self- Propelled Modular Transporters (SPMT) technology. The SPMT transport, a first in Australia in bridge application, allows the pre-fabrication of the whole bridge superstructure which significantly reduces traffic impact and road closures to the busy Southern Expressway.