Under the state budget, which is due to be announced on June 21, New South Wales will allocate $A 5.8bn towards the $A 8.3bn cost of constructing Sydney Metro Northwest and $A 6.2bn towards Metro City and Southwest, which has an estimated pricetag of $A 11.5-12.5bn.

"The Budget will continue the government's record commitments to public transport with not only $A 1.3bn in 2016-17 to continue work on Metro Northwest, but also $A 1.4bn in 2016-17 to continue the Metro under the harbour, through the CBD and on to Bankstown," says state treasurer Mrs Gladys Berejiklian.

Tracklaying is now underway on Metro Northwest, which is due to open in the first half of 2019. The 2016-2017 budget for Metro City and Southwest will cover tendering for twin-bore tunnels from Chatswood to Sydenham and preliminary construction, which is due to begin next year. Major construction will commence in 2018 and the line is due to open in 2024.

Last month the Australian Federal government announced it will commit $A 1.7bn to the Sydney Metro through the federal Asset Recycling Initiative (ARI), which predicates federal funding on the sale of assets owned by the states