Unveiling the preferred route for the Parramatta Light Rail project, NSW Premier Mr Mike Baird said the project will kick-start revitalisation and employment growth along the 22km corridor to Strathfield.

"The light rail network will help Parramatta reach its potential as Sydney's second CBD and be a major boost to existing public transport services in Western Sydney," he said.

The NSW government has been evaluating four shortlisted corridors for light rail in western Sydney and the preferred network includes a combination of two of these options.

The spine of the preferred route runs from Westmead to Strathfield via Parramatta incorporating Camellia and Sydney Olympic Park. Light rail will also replace the existing heavy rail shuttles between Parramatta and Carlingford.

The government has not provided an estimated cost for the project, but has indicated it will use 'value capture' from new developments along the proposed route to help fund it.

A Special Infrastructure Contribution (SIC) will be implemented, with the levy expected to be set at around $A 200 ($US 144) per square metre of gross floor area of new residential developments. Funds generated will be reserved for the light rail line and associated infrastructure such as schools and local road upgrades.

The SIC will be in addition to the $A 1bn the state government has already reserved in forward budget estimates, and additional funding contributions from federal and local governments will also be investigated.

No timeline has been announced, but transport minister Mr Andre Constance told local media he expects construction would begin during the term of the current government and move at a "cracking pace." "I would be hopeful that we would have this built within a five-year period," he says.

The announcement to convert the Carlingford line to light rail puts to rest previously-announced plans for an Epping - Parramatta heavy rail link, which would have utilised the Carlingford alignment. In 2010, the then federal government allocated $A 2.6bn towards that project, but it has been held in abeyance following a change of state government and plans the following year.