The federal government has committed to building and operating Sydney's second airport at Badgerys Creek but questions remain about whether it will fund the $400 million rail link for the site, 60 kilometres from the CBD.
Treasurer Scott Morrison has listed the Western Sydney Airport rail link among projects that have the potential to be supported through the government's new $10 billion national rail program, subject to a proven business case.
The federal government says it is partnering with the NSW government to investigate rail options for western Sydney to connect the airport to population and jobs centres, and unlock affordable housing, and further investment in the region.
The federal and state governments are also in talks about "Snowy 2.0", an expansion of the Snowy Hydro scheme.
Mr Morrison says the Commonwealth is open to acquiring a larger share or outright ownership of Snowy Hydro from the NSW and Victorian governments.
It is "subject to sensible conditions", including that the scheme would have to remain in public hands and Snowy Hydro's obligations under its water licence would be reaffirmed.
"All funds received by the states would need to be reinvested in priority infrastructure projects," Mr Morrison said.
The federal budget papers put the infrastructure spend in NSW at $18 billion, including the new airport and ongoing initiatives such as the $2.9 billion joint Australian-NSW governments infrastructure plan for western Sydney.