The Victorian Government has announced a $1.8-billion public-private partnership to overhaul Melbourne arterial roles.

Projects are set to include eight high-priority road upgrades, maintaining more than 700 kilometres of road from Werribee to Footscray.

It will also involve the duplication and widening of western roads.

Work should start in 2018 and be finished by 2022.

The construction and maintenance package will be funded through an ‘availability payment model’, which Premier Daniel Andrews says is an Australian first.

The same availability model was used to pay for Peninsula Link, a 25-kilometre freeway between Carrum Downs and Mount Martha.

It will see the private sector eligible for quarterly payments over 20 years to upgrade the eight roads and maintain the wider western suburban network.

Treasurer Tim Pallas said the project will bring a benefit-cost ratio of 4.4.

“What we're expecting out of the private sector is not just to build some roads but to make sure they're effectively managed and operating well,” Mr Pallas said.

“This is one of the biggest ever projects to update suburban arterial roads and it's going to create jobs, cut travel times and congestion and improve safety,” Premier Daniel Andrews said.

The Premier said no roads will be tolled as a result of the plan.