Construction of the underground extension from Kennington via Nine Elms to Battersea will start in spring 2015 and should be completed by 2020. The project will serve new property developments - including a new US embassy - in Vauxhall, Nine Elms and Battersea where a former power station is being redeveloped. The project is being funded entirely by the property developers through the creation of an enterprise zone which will be set up in 2016 and will operate for 25 years.

By 2020 LU expects to be operating at least 30 trains/hour on the Northern Line following the introduction of new trains. LU will increase peak-hour capacity on the Northern Line by 20% in December as a result of bringing a new CBTC signalling system into service.