The proposed 14-kilometre tunnel tollway between Rozelle and Allambie Heights will cost $14 billion to build, almost as much as the 33-kilometre WestConnex project.

The enormous price tag, in a costing for cabinet seen by Fairfax Media, excludes an extra $8 billion that would be spent on operation and maintenance of the tunnel over the first 35 years.

The Western Harbour Tunnel and Beaches Link tollway is expected to bypass up to 19 sets of traffic lights and cut the travel time between Brookvale and the CBD by 40 minutes. It will require the erection of six exhaust ventilation stacks for which sites have been identified, several within metres of schools.

The $14 billion price tag includes about $340 million for property acquisitions, $5 billion for the direct cost of construction, $2.3 billion for indirect costs and $5 billion for contingencies and cost escalation.