Property owners in Parramatta would pay an annual $110 levy for almost 30 years to help plug a $1 billion funding gap for the western Sydney light rail under a proposal transport minister Andrew Constance pushed to keep secret.

The levy is part of a Parramatta council-commissioned report by consultant AECOM outlining a $1.6 billion "value sharing" model to exploit increases in property values from the arrival of stage one of the $3.4 billion light rail.

It also includes an additional "special levy" of $110 a year on residential and commercial development within 800 metres of rail stops and a 3 per cent land tax on the value of properties in the same areas.

The model also proposes hypothecation of part of the anticipated increased stamp duty receipts from the light rail, sale of extra height to developers of nearby land and reservation of a third of council car park revenue.