The government has promised to fully duplicate Ashley Drive, committing a further $3.5 million on top of its ongoing $24 million upgrade of the congested Tuggeranong thoroughfare.
Transport is set to become a key election battleground ahead of October's ACT poll, and both sides have already made significant commitments on road infrastructure, including to upgrade Ashley Drive.
The ACT government last year pledged to duplicate a large stretch but not the entirety of the road, a $24.6 million commitment that included the construction of noise barriers and a pedestrian bridge.
But in March the ACT Liberals promised to duplicate all of Ashley Drive between Erindale and Johnson drives, warning the government's partial duplication would create bottlenecks.
On Wednesday, Transport Minister Meegan Fitzharris announced an additional $3.5 million over two years to complete the full duplication.
The funding will see the remaining 550-metre section of Ashley Drive between Ellerston Avenue and Johnson Drive upgraded to a dual carriageway.
Ashley Drive acts as a key access road for Tuggeranong residents, carrying around 22,000 vehicles each day, but becomes congested at peak hour.
Ms Fitzharris said a full duplication would relieve that pressure and help reduce congestion on other nearby roads.
"It will significantly assist residents in the surrounding suburbs. It will free up capacity on other roads that have some congestion at the moment," she said.
"We've paid a lot of attention to making sure the project is delivered well, is delivered in one go."
In announcing the opposition's commitment in March, shadow transport spokesman Alistair Coe described the government's plans to duplicate only part of the road as "peculiar".
"We think they're either playing games, and seeking to have another bite of the cherry down the track in the form of an election announcement, or they are simply not planning properly," he said at the time.
But Ms Fitzharris denied that was the government's intention.
She said next month's budget had given the government an opportunity to commit to the full duplication.
"Our main priority is making the commute easier and minimising the impact of roadworks to make sure we reduce congestion," she said.
"We had an opportunity in this budget to fund it, we've made two other significant road commitments in the budget already.
"Ultimately, it's really good news for [Tuggeranong residents].
"It means that there will be one road project to duplicate the full length from Erindale Drive, so there won't be any more disruptions.
"It's an extra 550 metres, so we'll be able to add that to the current tender, and they'll see one road project delivered, and we expect it will all be completed in 2017."
The works are currently underway.
Upgrades to Ashley Drive were first promised as an election commitment by former chief minister Katy Gallagher in September 2012, when the cost was put at $19.6 million with a completion scheduled for the 2015-16 financial year.
That completion date was pushed back in an announcement in May last year.
Labor member for Brindabella Mick Gentleman welcomed the commitment to full duplication, describing it as a "great announcement for the local Tuggeranong community".
He said the works were part of the government's plans for an integrated transport system.
"Through my conversations with many people in the Tuggeranong community, residents have been discussing their views on the importance of the Ashley Drive duplication, which will provide two additional lanes as well as additional safety measures at intersections and improved walking and cycling facilities completed to Johnston Drive," he said.