Premier Mike Baird has unveiled a $20 billion infrastructure plan just four months out from the NSW election, including a new western Sydney harbour tunnel.
Mr Baird and Roads Minister Duncan Gay said the plan will also include a second harbour rail crossing while the new road tunnel will allow up to 50,000 vehicles to bypass Sydney's CBD.
Mr Baird is proposing to sell 49 per cent of the state's electricity distribution network - commonly referred to as the "poles and wires" - to pay for the infrastructure drive.
The government plans to spend $1.1 billion for northern and southern extensions of the WestConnex motorway with construction not expected to start on a western Sydney harbour tunnel until after 2020.
"It will provide people travelling form western Sydney via the M4 with a direct link to employment centres in Sydney's north and north west," Mr Gay said in a statement.
"It would also provide an alternative route to Sydney airport from the north."
The western Sydney harbour tunnel is planned to start at Rozelle and run to Gore Hill or the Warringah Freeway.
The package, announced just four months out from the NSW election, includes $7 billion for the Sydney Rapid Transit - which will help link up the new North West and South West rail lines.
The government also plans on spending $4.1 billion on regional transport, a decision Deputy Premier Troy Grant described as a shot in the arm for country NSW.