The controversial East West Link will expand into an inner-Melbourne park while one of the project’s freeways receives a separate $850 million facelift.
Victorian Planning Minister Matthew Guy has obtained an extra 10.5 hectares for the project on request from the Linking Melbourne Authority, including a seven hectare parcel of Royal Park near the city.
Most of the land is for temporary use, to allow for construction of specific projects such as cycling paths.
The opposition has vowed to scrap the road project if Labor is elected in November and shadow planning spokesman Brian Tee likened it to a "horror movie" on Monday.
"What we've learned overnight, in secret the government has taken more public open space, much needed inner-city public open space, for a project that nobody wants that is going to devastate Melbourne for a generation," he told Fairfax radio.
"This is a exactly like a horror movie. We don't know what's going to happen from moment to moment.
"But every time we find out, the impact is worse, the loss of open public space is greater."
Premier Denis Napthine said one per cent of Royal Park, about 1.8 hectares, would be taken for the road which would connect the Eastern Freeway and CityLink.
"With the changes that have been made following the community consultation process, that land is now being largely taken to the west of the Upfield rail line," he told reporters.
"So it is significantly less impact on the park than previously outlined."
The Victorian government and toll roads operator Transurban also signed contracts for an $850 million widening of the CityLink-Tullamarine Freeway on Monday.
Dr Napthine said the upgrade would complement the first stage of East West Link as well as increasing the road's capacity by 30 per cent and decreasing travel time to the airport by 16 minutes in peak hour.
Transurban is funding the upgrade and its chief executive Scott Charlton said no extra toll points would be added, though rates for trucks will increase from April 2017, and the company has also been granted a future one-year extension to increase tolls by 4.5 per cent, or CPI.