The Victoria line was recommended in a 1949 report as it would reduce congestion on other lines. After some experimental tunnelling in 1959, construction began in 1963 and, unlike the earlier tubes, the tunnels did not have to follow the roads above. The line was originally approved to run from Walthamstow to Victoria station, the extension to Brixton being authorised later. As part of the works, Oxford Circus station was rebuilt to allow interchange with the Central and Bakerloo lines. Cross platform interchanges were built at Euston, Highbury & Islington and Finsbury Park. After running trains from Walthamstow, first to Finsbury Park and then to Warren Street in 1968, the line to Victoria was officially opened in March 1969. The extension to Brixton opened in 1971. Designed for automatic train operation, access to the platforms was by using magnetically encoded tickets collected by automatic gates.