BG&E provided structural, civil and facade engineering services for the Karuah Bypass – a vital part of the Pacific Motorway as it connects regional New South Wales (NSW), improving safety and reducing the travel time for road users.

Specifically, we 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. The two bridges 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 that provided simplifications to the cross section with time and cost benefits.

One significant feature of this project was the incremental launching of both bridges from the same casting bed at the western end of the Wetlands Bridge. 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. This method minimised 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.

At the time of delivery, these were the longest bridges incrementally launched in Australia.