Transport for London (TfL) has published a map showing the proposed route of its Bakerloo line extension.
A public consultation has begun into the project, which would extend the line south east from Elephant & Castle to Lewisham.
The extension would include four new stations: two along Old Kent Road, one at New Cross Gate and one at Lewisham. The existing station at Elephant & Castle may also be upgraded at the same time, with a larger ticket hall and wider Bakerloo line platforms.
TfL plans to apply for a Transport and Works Act Order for the line by 2020.
The extension will reduce journey times between Lewisham and central London, adding the capacity for 65,000 additional journeys in the morning and evening peaks.
TfL said the proposed route would support the construction of at least 25,000 new homes and the creation of 5,000 jobs.
In the TfL Business Plan, the delivery of the extension project has been brought forward by two years from 2030 to 2028/29. It also leaves the door open to a second phase beyond Lewisham.