Bridge structures on the Western Highway Anthonys Cutting realignment project

The A$200 million realignment of the Western Highway in Victoria between Melton and Bacchus Marsh involves the construction of approximately five kilometres of dual carriageway freeway on a new alignment which avoids the existing steep hills and dangerous curves of Anthonys Cutting. As well as five kilometres of dual freeway, the project also involves a new interchange at Bacchus Marsh, a smaller half diamond interchange at Hopetoun Park Road, a new overpass at Bulmans Road, and two bridge structure crossings of Djerriwarrh Creek and Pyrites Creek – 165m and 98m long respectively. These two creek crossings include bridge piers built using prestressed matchcast concrete segments, which at up to 30m in height are some of the tallest piers of their type in Australia. Along with the significant bridge structures, the project also involves the construction of cuttings and fill embankments of up to 25m in height which involved moving approximately 1.3M cubic metres of material. The project is being delivered under an alliance project delivery framework comprising of VicRoads, AECOM and John Holland and is programmed for completion in early 2012. The paper describes the selection of the various bridge forms used on the project, the use of precast segmental construction for the tall piers and some of the challenges faced in the design and construction of the bridges, particularly those built adjacent to high fill embankments and in steep terrain.