The Karuah Bypass is a vital part of the Pacific Motorway as it connects regional New South Wales (NSW) and improved safety and reduced travel time for road users.
BG&E provided structural, civil and facade engineering services, specifically, provided a design solution for the two bridges on the new freeway alignment. The western bridge, the Wetlands Bridge, is 218 metres long and the eastern bridge, the Karuah River Bridge, is 594 metres long, and are separated by the Horse Island crossing, which is 276 metres long. Each structure comprises twin, concrete box girders of uniform depth and an innovative, prestressing system.
One of the significant features of this project was both bridges were incrementally launched from the same casting bed, located at the western end of the Wetlands Bridge and then separated to form the two bridges. This allowed the bridges to be constructed with less environmental impact, compared to other construction methods.
The superstructure is supported on concrete piers founded on piles and pile caps. Abutments are generally spill-through, with one being a reinforced soil wall.
When the wetlands bridge reached its final position, the bridges were separated – the Karuah River Bridge was pushed over horse island into its final position.
At the time of delivery, these were the longest bridges incrementally launched in Australia.