Toowoomba Second Range Crossing – Constructing the Viaduct by Isaac Kirsch

Abstract

The $1.6 billion Toowoomba Second Range Crossing is a 41km heavy vehicle route jointly funded by the Australian and Queensland Governments on an 80:20 funding split arrangement. The route is designed to increase freight efficiency and significantly improve driver safety and community amenity by removing heavy vehicles from Toowoomba’s CBD. When finished, the Toowoomba Second Range Crossing will connect the Warrego Highway at Helidon Spa in the east to the Gore Highway at Athol in the west via Charlton. The project will create a safer, faster and more efficient route for connecting freight to major ports and markets. The Project features: • Four lanes (two each way) from Warrego Highway east interchange at Helidon Spa, to Warrego Highway west interchange at Charlton; • Two lanes (one each way) from Warrego Highway west at Charlton to Gore Highway at Athol; • Grade-separated interchanges at Warrego Highway east, Warrego Highway West, Toowoomba-Cecil Plains Road, and Gore Highway; • Grade-separated connections to Mort Street and Boundary Street in Toowoomba City; • A 30-metre deep cutting at the top of the Toowoomba Range, with the continuity of the New England Highway by two arch bridges over the cutting; • And, an 817m-long viaduct connecting the Lockyer Valley and Mount Kynoch. Of particular note, is the viaduct which is a new engineering and construction process for the Darling Downs region. Construction of the viaduct began in September 2016 and was completed in December 2018. It is comprised of: • 26,000 cubic metres of concrete • 5,000 tonnes of reinforcement • 120 piles between 6m and 20m deep • 21 piers (22 spans) ranging from 12m to 51m in height • 242 pre-stressed concrete Super T girders (11 per span) • Super T girders ranging in length from 30.366m to 37.804m, and mass from 71.3t to 88.5t This paper explores the details behind the design and construction of the viaduct, including: • Why a viaduct? • What was the construction program of the viaduct? o What do the foundations consist of? o How were the piers lifted? o How were the girders placed? • With the girders being so long and heavy, how were they transported from Brisbane up the Range? • What other challenges of design/construction were faced?