Sydney Business Chamber western Sydney director David Borger said two light rail lines, rather than one, could be built if a "betterment levy" was paid by private landowners who benefited from their construction.

Mr Borger also said value capture, a form of public financing that aims to recover profits that land owners get from public infrastructure, would accelerate the building of the light rail line and make the project less reliant on expansions in state government funding.

"The Harbour Bridge had a levy that stayed on for 15 years and helped pay for some, not all of it. I don't think we can ignore the potential for value capture in this conversation," Mr Borger told the Western Sydney Light Rail Conference in Parramatta on Friday.

"It's fairly simple to administer and can apply just to businesses or residential properties, so that those with the most uplift in value pay a little more."

The director of the Parramatta branch of Starr Partners real estate agency, Adam Denina, said he expected property values to increase 15 per cent as a direct result of the construction of the line.

"Castle Hill properties have already gone up in the last 18 months, probably the better part of 25 per cent, and Parramatta properties have probably gone up around 35 per cent," Mr Denina said.

"The closer you get to the light rail being completed the more they'll go up. There's already talk about it."

Lisa Surian, the director of Raine and Horne Parramatta, also said the demand for houses, including those up to 20 minutes walk from the light rail, would skyrocket.  But she didn't think it fair that the land owners should hand over the windfall the light rail would give them.

"I just don't see how a mum and dad who bought a house 30 or 40 years ago and are now on a rail line should have to pay. That's a family asset that people have worked towards and paid off."

AECOM's infrastructure advisory technical director Joe Langley told the conference that Australia had fallen behind, with most major light rail projects around the world partially funded using value capture methods.

"There's something inherently unfair in that you could walk away with that sort of value without some of that value being put into the infrastructure," Mr Langley said.

"We need to think about infrastructure as creating value, as an investment and not as a cost."

Mr Langley also said allowing high density construction along the light rail line without recovering some of the value would be a "big mistake".

"I think we need to be careful about giving away density," Mr Langley said.

"If we give away density without extracting something to fund the infrastructure that is necessary to avoid the congestion that results from that, I think we make a big mistake. I think we lose value as a result of that."

The state government this week revealed another $600 million would be set aside for the light rail project, on top of the $400 million already allocated.

There are four possible routes it could take: Parramatta to Macquarie Park via Carlingford, Parramatta to Castle Hill via Old Northern Road, Parramatta to Bankstown and Parramatta to Sydney Olympic Park and Strathfield/Burwood.