A light rail line from Westmead to Homebush via Parramatta as well as another light rail line to Carlingford has been announced by the New South Wales Government.

The Government decided lines to Homebush and Carlingford were the best of four options. ( ABC News )

Transport Minister Andrew Constance said the two new light rail lines would open up more of western Sydney.

"It's very pleasing to announce a network and not a route," he said.

"From Westmead Hospital to the Sydney Olympic Stadium, this is a win for everybody.

"Light rail can move 10,000 passengers per hour.

"We have the benefit of linking it to the hospital, through the CBD, to Parramatta and of course to other major development precincts along the route."

The NSW Government had been considering four shortlisted routes for the light rail for more than a year.

Mr Constance said community groups in both areas had advocated for light rail.

"We did assess four particular routes and it's very pleasing, given the advocacy that we've seen for both the Carlingford Line and the Sydney Olympic Park Strathfield line, that we're able to implicate both of the groups that have been advocating in this regard.

"We're going to see a major build happen very quickly."

Premier Mike Baird said the announcement marked "a fantastic day for the people of western Sydney, for the people of Parramatta."

"We are bringing the light rail revolution that is going across this great state, here to Parramatta, here to western Sydney," Mr Baird said.

The new route was widely welcomed by transport groups, including the Tourism and Transport Forum.

"For over 100 years, public transport has been designed to get people from the outer suburbs to the Sydney CBD for work," said Ms Osmond.

"Finally we are starting to see that concept being broken down and a new focus on building up Western Sydney as a genuine, independent economy by improving intra-connectivity.

Ms Osmond said the light rail line to Carlingford was an important first step towards connecting Parramatta to jobs hubs at Macquarie Park, but she called for the Government to go further.

"What the NSW Government has put forward goes halfway to achieving this, with the indication that an extension from Carlingford to Macquarie Park could be the next stage," she said.

"We need to see a more concrete commitment from the Government to deliver this missing piece to ensure this route reaches its full potential."

Light rail linked to job growth in the west

The western Sydney director for the Sydney Business Chamber David Borger said the light rail was good news for workers.

"What the light rail announcement today really does is says, 'Look, there is an eight kilometre precinct between Sydney Olympic Park and Westmead, so this is the area where you might get some of these so-called knowledge jobs in the future'," Mr Borger said.

"So if we can connect these jobs with public transport it's really a way of supercharging employment growth."

However, Opposition Leader Luke Foley was critical of the timing of the light rail announcement and said it came too late to convince major employer Commonwealth bank not to move 8,000 jobs from western Sydney.

"I've been calling for this all year and the Government said, 'We have to do the sums and we have to be able to explain the costings and the timetable before we announce the route,'" Mr Foley said.

"Today they announced the route without costings and a timetable. Perhaps they could have committed to this route as I did several months ago, and perhaps the Commonwealth Bank would have stayed."

In contrast to the Commonwealth Bank's decision to leave the city's west, Mr Baird today announced more NSW public sector jobs would be moving there.

Mr Baird said all 1,800 Education Department jobs would be moved from the city to Parramatta by 2020.

Light rail final costings yet to be determined

The lines will be partly funded by a special infrastructure contribution paid by developers who build homes around the light rail corridor.

New South Wales Premier Mike Baird and Transport Minister Andrew Constance announcing the route the new Sydney light rail will take in western Sydney. ( ABC News: Stephanie Dalzell )

But Mr Baird was unable to say how much the developers would be charged, or what the total price tag of the project would be.

"We are now moving towards the final business case mode of this, which will determine the final costings, the final configurations and the final contributions that will come," he said.

Mr Baird also would not put a firm finish date on the project.

But the Transport Minister said he expected construction would begin during this term of government and move at a "cracking pace".

"I would be hopeful that we would have this built within a five-year period," Mr Constance said.

"But I'm not going to give a timeframe in terms of unrealistic timeframes."

He said part of the network would go down an existing rail corridor, which would make it easier to build.

Mr Baird brushed off criticism that large parts of the proposed new line would duplicate existing heavy rail routes.

"In modern cities, you need multiple options, you need connectivity," he said.

"This goes to places where heavy rail doesn't and it connect in to it.

"So what this does is it opens up new suburbs and new opportunities for people both in terms of access to a public transport system and then a connection into heavy rail."