Toowoomba Bypass
Toowoomba, Australia

Owners: Nexus Infrastructure Consortium and Queensland Government
Lead Design Firm, Contractor and Civil and Structural Engineer: Nexus Delivery JV (Ferrovial & Acciona)
Subcontractors: Colas Queensland Pty Ltd. and Q&Birt Pty Ltd.

Winding 41 kilometers through southern Queensland in Australia, the Toowoomba Bypass serves as a vital economic link while boosting mobility and driver safety. The largest federally funded road project in the country’s history, the $1.6-billion highway included grade-separated interchanges, an 830-m-long viaduct and 30 other major bridge structures. Crews moved 10 million cu m of earth, installed more than 200 km of longitudinal surface drains and used more than 2,000 pieces of heavy equipment amid complex, steep geological conditions.

The contractor set a construction first in Australia by laying foam bitumen in one layer of widths up to 8.4 m, providing a sound platform upon which to pave asphalt layers. This resulted in a high-quality pavement depth and strength with less materials and ultimately less road noise.

Foam bitumen was used for 28 km of the four-lane roadway and generally placed as the base layer for pavement at 250-mm thickness, says Daniel Perez, area manager for joint venture Nexus Delivery. About 400,000 tons of foam bitumen were produced.

Crews built the lengthy viaduct using a jump form system for the piers, in 4.5-m lifts, and a launching truss gantry for the precast Super T girder beams that form part of the deck, says Perez. The 38-m-long beams weighed 90 tonnes. The project is expected to boost economic activity in the region by $2.4 billion over 30 years, with the new highway diverting almost 80% of heavy commercial vehicles from the original crossing and from Toowoomba’s central business district, he adds.

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