A new 27-kilometre highway bypassing Bunbury and saving motorists up to 20 minutes in travel time to the South West is now officially open.
The Wilman Wadandi Highway, which connects the Forrest Highway and Bussell Highway, will divert around 15,000 vehicles from local Bunbury roads every day.
Drivers heading down south to Busselton, Dunsborough and Margaret River will avoid 13 sets of traffic lights on their journey.
The new four-lane road includes five bridges, four grade-separated interchanges, and 19 fauna crossings and is the biggest road project ever delivered in the South West.
"We've seen significant growth around Bunbury and the clash of local traffic, with tourist and freight traffic heading to the South West was no longer sustainable," Transport Minister Rita Saffioti said.
"The Wilman Wadandi Highway will reduce congestion on local Bunbury roads and make the commute to and from the South West around 20 minutes faster for thousands of motorists every day.
"This is the biggest road project we have delivered in the South West, and will ensure our road network remains safe, efficient and reliable for many decades to come."
Motorists are being encouraged to head to the Main Roads website to familiarise themselves with the new road before beginning their journeys.
Some minor works will still be underway across a range of areas including on some local roads, landscaping, artwork, and minor tie-in works.
The Wilman Wadandi Highway has been jointly funded by the Australian and Western Australian governments.