Sydney's motorways have become an even bigger money spinner for Australian toll road king Transurban, which is eagerly awaiting the chance to swoop on WestConnex if the Berejiklian government opts to sell.

"Everyone is talking to everyone," Transurban chief executive Scott Charlton said of the large investor interest in buying in to Australia's largest motorway project.

Mr Charlton said WestConnex would be like a mini-network, making it cheaper to operate than a single toll road.

"It's more like a business in its own right as opposed to maybe just one single standalone asset," he said on Tuesday.