Boris Johnson has launched a public consultation for a new road tunnel at Silvertown and new vehicle ferry crossing at Gallions Reach.
Transport for London say the proposed tunnel could carry 6,000 vehicles per hour and connect Silvertown with the Greenwich Peninsula.
The proposed ferry service would replace the existing service at Woolwich.
The Mayor said the two river crossings would “be an enormous economic boost to Londoners living and working in the east of the capital, facilitate further regeneration and development, and help to keep our city moving.”
The Mayor added: “I hope Londoners will get involved with this consultation and make their voices heard on these exciting proposals.”
According to TfL, the ferry crossing would not be operational until 2017 and the tunnel would not open until 2021. Both dates are subject to receiving planning permission to allow construction to start by 2015.
Green Party Assembly Member Jenny Jones has called on the Mayor “to make a firm commitment” that the tunnel would not be funded from bus and Tube fares.
Jones said: “People using public transport may not be bothered about the new road, but might be very against it if they have to pay even higher fares.
“This consultation on the principle of building a new road at Silvertown is therefore a farce and the Mayor should shelve the whole thing until we know how much it costs and who will be paying.”
Friends of the Earth London Campaigner, Jenny Bates said: “New crossings for vehicles across the Thames are not the solution to London’s transport woes – they could increase traffic, worsen air pollution and add to climate-changing emissions.
“If the Mayor wants to cut congestion and increase the resilience of existing crossings and aid regeneration, he should make it easier for people to leave their cars at home and travel locally by public transport, bike and on foot – all of which would help free up existing road space and can save commuters cash.”
The public consultation runs until Monday 5 March and Londoner’s can share their views via the TfL website.