The estimated cost of Sydney's WestConnex motorway has increased by half a billion dollars, as the state government pours record amounts of money into new road and rail projects.

Treasurer Gladys Berejiklian's first budget accelerates funding for a host of transport initiatives – such as a new metro rail line through the city – even before the planned privatisation of electricity assets.

The cost of WestConnex has risen to $15.4 billion, more than $5 billion above initial estimates in 2012.

But the bulk of the transport funding in the budget is directed at major projects already announced or under way, such as the North West Rail Link, now called Sydney Metro Northwest, and the 33-kilometre WestConnex motorway.

The cost of the WestConnex project was estimated at $15.4 billion in Tuesday's budget, $500 million more than estimated in last year's budget, and a steep increase on the initial $10 billion project announced in 2012 by Infrastructure NSW.