AN 80-METRE rail underpass connecting Glenfield to the South West Growth Centre at Leppington has been completed.
The drilling of the seven-metre high, nine-metre wide track took place beneath the Hume Highway at Glenfield.
The underpass will connect urban and rural Sydney in one continous, express line into the city.
Transport Minister Gladys Berejiklian said she hoped the milestone would give a real sense of the project's scale. "The South West Rail Link is surging ahead and a major engineering feat has been completed," she said.
"Since last November, 6000 cubic metres of rock has been removed from beneath the busy eight-lane section of the Hume Highway at the Ingleburn Gardens estate in Glenfield.
"The underpass will house twin tracks for trains to travel underneath the highway. And construction of major bridges for the project is progressing rapidly, with the successful installation of large concrete beams over Campbelltown Road, Camden Valley Way and Cowpasture Road."
She said the project would include a new 11-kilometre rail line from Glenfield to Leppington, with new stations and commuter parking at Edmondson Park and Leppington.
Macquarie Fields MP Andrew McDonald, said "the contract . . . was assigned by the previous Labor government and I am pleased the Liberal government honoured it, despite financial pressures.
"What we now need to see is evidence that trains will travel between Leppington and the city, how many carriages they will have and how frequently they will run.
"One of the major reasons the line is costing so much is because it runs separately to the East Hills and South Line, so we need to see that this line will be utilised."
Dr McDonald said the new line would also help drive housing development in the South West Growth Centre.
Passenger services are scheduled to begin in 2016.