Rail travel between Sydney and Gosford on the Central Coast will be reduced to 25 minutes on a fast-rail link between the two cities, under funding pledged by the NSW and Commonwealth governments.

NSW Premier Dominic Perrottet today announced $500 million for a fast rail upgrade to the Sydney-Central Coast train line would be part of this month's state budget.

The promise is conditional on the new federal government's election campaign pledge of $500 million in its first budget for corridor acquisition, planning and early works for fast rail between Newcastle and Sydney.

Mr Perrottet said the total $1 billion investment by the federal and state governments would make the upgrade a reality, and commuters would eventually see considerable reductions in travel time.

"Once this becomes a reality we will be seeing travel times between Sydney and Newcastle [reduced] from two and a half hours down to one hour, Sydney to Gosford in 25 minutes, then Sydney to Wollongong in 45 minutes," he said.

"Today's half a billion dollars will make that vision come to life."

Parliamentary secretary for the Central Coast Adam Crouch also announced funding for a new University of Newcastle campus to be built in Gosford. 

"This is a very historic day for our region — a half a billion dollars into our rail network and another additional $18 million going into providing the delivery of a University of Newcastle campus right here in Gosford," Mr Crouch said.

The NSW funding for the Gosford university campus also matches Commonwealth investment.

Mr Perrottet said the rail upgrades were an essential step in delivering his government's six cities vision, by improving accessibility between the state's major centres.  

"You can't build great cities without building significant transport infrastructure, and … this billion dollars from the state and federal government will lay that foundation and set up further investments as we move forward," he said.

The funding will allow construction to begin on the first stage of the Northern Corridor, including two new electrified rail tracks between south of Tuggerah and north of Wyatt, new platforms and station upgrades at Wyong and Tuggerah, and new bridges.

Committee for Sydney CEO Gabriel Metcalf said the combined government funding would help deliver a "transformative" fast rail project.

"Getting on a trip from Gosford to the city in 25 minutes and Newcastle under an hour will be a game changer for commuters, students and many others," he said.

"It will reshape the geography of our city.

"Better connections across this region, south to Wollongong, north to the Central Coast and Newcastle, and linking into Sydney's west, means we will effectively work like a bigger global city, with more economic gravitational pull."