Cars will pay about $3 a trip to travel along the new road, but will not pay a toll to drive along the widened section of the West Gate Freeway. Trucks will pay a $13 toll along the length of the road, including the West Gate Freeway. Under the funding model, toll concessions for Transurban along CityLink will be extended for between 10 and 12 years. Transurban shares became the fifth-fastest riser on the ASX200 on Tuesday, rising 2.6 per cent in a market that fell by 0.9 per cent.

The government says the business case has identified a cost benefit-ratio of $1.30, using conservative methodology. The $400 million upgrade of the Monash Freeway has been included in the project and has boosted the benefit-cost ratio from $1.10 to $1.30, Premier Daniel Andrews said. "This represents value for money, it is a strong proposal creating thousands of jobs," Mr Andrews said. "This project stacks up, it will save time and create jobs … we are going to build this road and work will begin next year." He described the project as "elegant".

He also said analysis using other BCR methods, such as those used by Infrastructure Australia, found the new toll road to deliver a $1.90 benefit for every $1 invested. The project will be funded through government contributions, new tolls on the road and extending existing CityLink tolls. The state already has $1.5 billion worth of federal funds from the dumped East West Link, Mr Andrews said, and he hopes the Turnbull government would be a "strong partner". "Given it is such an effective answer to the congestion that is holding us back I can't see how the federal government wouldn't want to be a strong partner. " The Premier indicated the state would make a contribution similar to that of the Monash upgrade, which is expected to be $400 million.

Mr Andrews said the project would make the roads safer by reducing the number of serious accidents by 55 per cent. Other benefits listed by the government include: 5600 construction jobs

Reduction in vehicle emissions by 2.3 million tonnes a year

Boost the economy by $11 billion

Take 50 to 75 per cent of trucks off Francis Street and Somerville Road in Melbourne's west

The road will service 22,000 vehicles a day

Build the missing link for cyclists along the Federation Trail Mr Andrews said there were still some technical details to be worked out including how far into the city the road would come, indicating it could come as far as Wurundjeri Way . Despite spruiking the new independent Infrastructure Victoria body to assess major projects, the Western Distributor has not, or will not, be scrutinised by the body because the proposal pre-dates Infrastructure Victoria.

But Mr Andrews said the project went through similar and thorough scrutiny by officials. Transurban chief executive Scott Charlton said work on the Webb Dock access would begin soon, with a contract for the Monash upgrade to be signed next year, before contracts and final plans for the Western Distributor in 2017. The Opposition attacked the government for releasing an unfunded project declaring the announcement nothing more than a distraction from the Premier's relationship with the CFMEU secretary John Setka and a union stoush with the firefighters who protested at parliament on Tuesday. Shadow Roads Minister Ryan Smith said however that a future Coalition government would honour all contracts. "The claimed 'immediate' 20 minute saving on the Monash Freeway will not be delivered for another seven years, and the 6000 trucks that will be removed from the West Gate Bridge is a mere 3 per cent of the 200,000 vehicles that used the Bridge each day," Mr Smith said.

"By comparison the East West Link would have provided capacity for 100,000 vehicles a day, allowing for a 50 per cent reduction to bridge traffic." The Greens also raised concerns about another toll road and lamented that western suburbs resident's concerns had not been listened too. Brian Negus, director of public policy for transport group the RACV, said Melbourne would get the second freeway river crossing it had needed for many years. "Improvements to the Monash Freeway are also critical and it's good to see the eastern side of the city benefit from the project as well," Mr Negus said. Victorian Transport Association chief executive Peter Anderson said the trucking industry wanted the new road built.

"While we do have some reservations about a tolling regime on the new road that will likely see transport operators paying a large premium compared to other vehicles, the main thing is that the road is going to be built," Mr Anderson said. Toll operator Transurban unveiled the plan as an unsolicited bid in March 2015, proposing an alternative to the East West Link that would connect the West Gate Freeway with the CityLink, the city and the port using a tunnel and raised roads. Under its original proposal, Transurban offered to pay about one-third of the construction cost, with one-third paid for by a 10 to 15 year extension on the existing CityLink tolling period. The company proposed that the remaining third of the cost would be met by the Commonwealth, with no contribution from the Andrews government. Labor has long argued that federal money previously set aside for the East West Link should be diverted into the proposal. The Andrews government handed the business case to the Commonwealth only last week. It is understood that so far the Commonwealth has not committed any cash to the project. Martin Wurt, the secretary of the Maribyrnong Truck Action Group, said he was not surprised the road was going ahead.

"But if they are going to do this tunnel, it has to be supported with state-of-the art filtration of vent stacks for diesel fumes. It's one thing to put the trucks underground, but if all those fumes are just going to be coming out those vent stacks, then it's hardly a win for residents." And he said there needed to be a ban on trucks using residential streets once the tunnel was finished. "We've been promised these big road solutions in the past, and they have just added to our problems with trucks shortcutting through our neighbourhood - there needs to be no option for them to short-cut."

