A massive announcement from Premier Daniel Andrews this morning.
He's unveiled plans for a multi-billion dollar underground rail loop connecting Melbourne's train lines from Cheltenham to Werribee.
The Premier says it's a "critically important" decision, and will create about 20,000 jobs.
The section from Cheltenham to Melbourne Airport will cost between $30-$50 billion.
Construction on the first part of the project will take a decade, beginning in 2022.
Spring Street is yet to secure federal funding.