The NSW government should borrow money at record low interest rates or sell off more assets like the WestConnex motorway to build more transport networks amid concerns projects are stalling because they can't be funded, the Committee for Sydney says.

"Sydney has outgrown the ability to be so reliant on just a car-based transport system," Committee of Sydney's chief executive Gabriel Metcalf told The Australian Financial Review. "Sydney is becoming a major world city and it is now big enough that it needs a sophisticated mass transport system more like what you would see in London."