A second rail link across Sydney Harbour has been given the green light, after the state's electricity sell-off was passed by NSW parliament.

The new transport additions are possible after the government successfully passed a bill to lease 49 percent of the state’s electricity assets, popularly termed the “poles and wires”.

The sell-off will net the government around $20 billion, $11 billion of which will be chewed up by the new infrastructure.

Premier Mike Baird and Transport Minister Andrew Constance were on hand today as test drilling took place in the harbour.

“The button has been pushed, it is green light, good to go,” Mr Baird said.

The underground tunnel is expected to be completed by 2024. (9NEWS)

The rail crossing under the harbour would begin around Chatswood or St Leonards on the lower North Shore before popping up again in Sydenham, possibly via Barangaroo.

The newly branded Sydney Metro, previously known as the North-west Rail Link, would then head to Bankstown via Campsie, Lakemba and Punchbowl.

The link is expected to be operational by 2024.

“It’s going to be one of the most transformative public urban transport projects you will ever see,” Mr Constance said.

Labor is pressuring Premier Mike Baird to deliver on his election promises. (9NEWS)

The pressure is on Mr Baird’s government to deliver, with the rest of the money filling the state’s coffers to go towards new roads, hospitals and schools.

Labor, the Shooters and Fishers Party and the Greens opposed the measures in the Senate, but the motion was passed with help from the Christian Democrats.

Opposition leader Luke Foley has vowed to hold his counterpart to account over what he termed “very grand promises”.