The proposed F6 Extension toll road from Sydney to Wollongong would charge about $10 for each one-way journey, according to a leaked planning document seen by Fairfax Media and the ABC.

The return toll of around $20 would amount to $100 per week for people who commuted from Wollongong to Sydney five days a week.

The Cabinet in Confidence document says the tollway between St Peters and Waterfall would open in stages during 2024 and 2025 and would be tolled for 35 years during which the government or a private owner would reclaim the $14.5 billion it cost to build and the $3.5 billion it would cost to operate.

The toll would rise rapidly during that time, doubling from $10 to more than $20 over the first 20 years in line with a formula that lifts the toll by at least 4 per cent per year instead of the inflation rate of around 2.5 per cent. After 20 years the toll would rise with inflation.