After years of delays, cost overruns and the discovery of toxic soil that triggered a legal battle, Melbourne’s West Gate Tunnel will finally open on Sunday.

The $10.2bn project, consisting of 6.8km of tunnels and 9.2km of elevated roads, will provide a new river crossing and act as an alternative to the West Gate Bridge.

Announcing Sunday’s opening date on Friday, the premier, Jacinta Allan, said it would “transform” the way motorists move around the city and state.

“This is a project that’s much more than just two tunnels – as big and impressive as they are,” Allan said.

The project includes a 2.5km ‘veloway’ – an enclosed cycling path connecting Footscray to the Docklands. Photograph: West Gate Tunnel Project

“This is a project that’s also widened the West Gate Freeway, putting extra capacity into the West Gate Freeway, [and] alongside delivering that direct access into the Port of Melbourne, it’s providing alternate access around the city, particularly around the northern parts of the city.”

Allan also highlighted the 14km of new walking and cycling links, including a 2.5km “veloway” – an enclosed cycling path connecting Footscray to the Docklands – as well as a 24-hour truck ban on local streets that comes into effect when the tunnel opens.

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She said it was expected to remove 9,000 trucks off streets in Melbourne’s inner west, though the roads minister, Melissa Horne, said the national heavy vehicle regulator would be “focused on education” rather than imposing fines immediately.

Horne said it would “take a little bit of time” for motorists to get used to the new road network, and the opening is “not going to be without its challenges”.

The project was a joint venture between the government and toll road operator Transurban, which pitched it to the Andrews government in 2014. Construction began in early 2018 and was originally scheduled for completion in September 2022.

But the discovery of toxic soil – a common issue in former industrial areas like the one where the tunnel was built – led to a legal standoff between the government, Transurban and the project’s builders, which contributed to delays and a $3.4bn budget blowout.

Transurban has contributed $6.1bn of the project’s construction cost, in exchange for operating tolls on the new road and a 10-year extension to its CityLink contract.

Under the agreement, motorists will be slugged $4.09 for a car and $6.54 for a ute or van – or $6.54 and $10.47 respectively if they exit into Dynon Road, Footscray Road or Wurundjeri Way during the morning peak of 7am to 9am.

The toll is in addition to the existing CityLink charges, meaning a car travelling through the West Gate Tunnel and onward along the Tullamarine Freeway to Melbourne Airport will pay $10.63.

Allan defended the tolls, saying motorists were being provided with more choice.

“It’s only on the new parts of the infrastructure,” she said. “There are many other ways to move around our city and state, so it is giving people choice – you can have the bridge, or the tunnel,” she said.

She also said travel will be free on weekends in January, after she urged Transurban to match the government’s commitment to free public transport over the summer to coincide with the opening of the Metro Tunnel.

Now in its third term and sliding in the polls, Labor is pinning its hopes on both of the infrastructure projects delivering political capital before the November 2026 state election.