The NSW government has been instructing transport officials to ignore public transport alternatives to motorway projects, according to explosive internal documents obtained by Fairfax Media.

The revelation emerges in a memo prepared within Transport for NSW into potential rail improvements between Sydney and Wollongong – a project that could compete for funds with the proposed F6 motorway from the WestConnex interchange at St Peters to Waterfall.

But the document also suggests that the government has excised the development of public transport alternatives to other major toll-road projects. These include the Western Harbour Tunnel project, which is to be an extension of WestConnex, and the Beaches Link tunnel that is to extend that road to the northern beaches.

The memo prepared within Transport for NSW says a new rail tunnel and freight line could cut the time taken for commuters to travel from Wollongong to Central from 90 minutes to about 60 minutes for as much as $10 billion less than the cost of the toll road.