Western Australia has opened the $705m Kwinana Freeway extension and Forrest Highway, the state’s biggest ever road project.

The continuous dual carriageway connects Perth and Bunbury in the state’s South-West and will reduce travel time between the two cities by 30 minutes.

The project was funded with $375m from the state government and $330m from the federal government.

Construction involved building the Murray River Bridge consisting of two separate structures of 272m each, a Serpentine River bridge consisting of two separate structures of 112m each and a 70.5km section consisting of six interchanges, ten intersections and 19 bridges.