Western Australia's road planning authority is hoping to sink parts of the Charles street thoroughfare near the Perth CBD in a bid to reduce congestion and make the area more attractive for pedestrians and cyclists.
The plan, released by Main Roads WA, would see 'duck and dive intersections' built where the road cuts through Vincent street, Scarborough Beach road and the Green-Walcott-Wiluna streets intersection.
Below-ground roads will take Charles street traffic under the three intersections and out the other side.
In a concept video, put online this week, a spokeswoman said the road was "under pressure" and expected to get busier amid a surging population.
"Today Charles street is a four-lane predominantly undivided road," the video's voiceover said.
"It is congested with limited places for pedestrians or cyclists to cross, as well as an unattractive corridor to walk along or wait for buses.
"Given the constraint nature of Charles street, it was necessary to develop creative solutions."
The project is not yet funded and no time line has been set.
WA's first duck and dive intersection at Armadale road and Solomon road was completed late last year.
The concept has also been proposed for several other busy roads around Perth, including on West Coast highway in Scarborough where the trench design was criticised for being outdated and a step backwards.
Property acquisitions on the cards
The project will also include a median strip in the middle of Charles street.
In a letter to residents, Main Road director of road planning Lindsay Broadhurst said the design was part of a "long-term planning review", but admitted there would need to be extra land acquired if it were to go ahead.
"The concept will require additional land beyond the current Planning Control Area that already exists along Charles street," she said.
"The planning review and concept will inform a future planning control area and an amendment to the Metropolitan Regional Scheme that ultimately reserves the land required for the future Charles street."
City of Vincent chief executive David MacLennan told the ABC's Nadia Mitsopoulos that could mean the demolition of some houses.
"In order to institute road widening of this magnitude, land would have to be acquired by the state government through the planning commission to allow that widening to occur," he said.
"If the current widening was increased from what's already outlined in the planning control area, yes, there would be some compulsory property acquisitions.
"[But] I would say that is some way off."
Traffic manageable, frustration low
The local council was yet to adopt a formal position on the road, but Mr MacLennan said there was broad support for increasing riding and walking in the area.
He also said traffic at the intersection was "manageable" in the area and was only busy at peak times.
Locals such as Simon Nelson agreed.
"I have personally never taken much frustration to this intersection, and I have lived in the area for nearly a decade," he said.
Mr Nelson has been living on Charles street near the Vincent street intersection for almost a year.
He said while it was good that planners were thinking about the future, he was "doubtful" the project could be pulled off smoothly.
"I am concerned about two years of terrible roadworks and increased traffic here would be worse than it already is," Mr Nelson said.
Evan Ingley has lived near the intersection for about 30 years and said he was still trying to work out what the plan would mean for him.
"It looks to be very expensive," he said.
"I'll be interested to see the full plans. Would it be easy for me in the different ways I go across that road, as a pedestrian, as a cyclist, and on a scooter?
"It's a different concept to changing an intersection, with an underpass for the cars as opposed to having an underpass for pedestrians. That should be a concept that we take on board.
"So I would encourage the state government to fund at least part of it to get that concept up and running."
The plan has been put to the community for comment.
