Sydney fast train will slash travel time

A fast train connecting Sydney's CBD and Parramatta could cut commuter travel time by half.

The journey, following four proposed routes, would take just 15 minutes a discussion paper commissioned by Parramatta City Council and the Sydney Business Chamber found.

The fast train would also connect Parramatta to the proposed western Sydney airport at Badgerys Creek on a new line via Blacktown or Liverpool with an estimated travel time of 25 minutes.

It would reach speeds up to 160km/h, similar to the Hong Kong Airport Express and London's Heathrow Express.

"If we are serious about being a polycentric city with multiple employment nodes then we need a transport system that can deliver fast reliable and frequent connections," the Sydney Business Chamber's western suburbs director David Borger said on Friday.

Almost half of Sydney's population lives in the west, a region predicted by the chamber to grow faster than other city areas.