And investments, including the Underground's current star project, the Jubilee Line extension, have sometimes been guided more by political considerations than by careful cost-benefit analysis.
But the project's current phase also includes replacement of five two-track bridges, which required reducing the number of active tracks from four to two.
Dray Horse Yard, which includes a multiplex cinema and restaurants, was opened at the site in October last year as part of the project's current phase two.