Transport Minister Andrew Constance has announced the start of the tender process to build two twin tunnels between Westmead near Parramatta and the Bays precinct in Sydney's CBD.

The two tunnels, which run from Westmead to Sydney Olympic Park and Sydney Olympic Park to The Bays, will together form part of a larger 50 kilometre tunnel.

Mr Constance says the project will create more than 10,000 direct jobs and 70,000 indirect jobs.

"The construction of this mega project will create many thousands of new jobs and support families across Sydney," he said in a statement on Wednesday.

"These contracts will require tunnellers, electricians, plumbers, carpenters, concrete workers, truck drivers, labourers and security guards."

The Sydney Metro West project will provide an underground driverless metro railway which is expected to cut travel times to around 20 minutes between Parramatta and the city.

The proposed stations will be at Westmead, Parramatta, Sydney Olympic Park, North Strathfield, Burwood North, Five Dock and the Bays Precinct.

The transport minister last year told a budget estimates hearing the government had allocated about $6.4 billion for the project, but the final cost would be revealed after the contract was signed.

Boring is expected to begin before the end of 2022.

Australian Associated Press