Transport for London (TfL) has confirmed that introducing driverless trains to the Underground would be a costly and inefficient project, following a study commissioned by the Department for Transport (DfT). The study, which focused on converting the Waterloo & City and Piccadilly lines to driverless operation, concluded that the enormous expense of implementing new rolling stock, signalling systems, and platform edge doors would not result in significant benefits.

The primary advantage of driverless trains is increased capacity, as automated control systems could allow trains to run closer together. However, modern signalling systems already enable tube lines to operate near their maximum capacity, meaning the costs associated with the switch would be disproportionate. Additionally, increased frequency would require major upgrades to stations, including expanded platforms, which would be difficult or impossible at certain locations.

The total cost of converting each line to driverless operation is estimated to be in the billions, with the entire Underground potentially requiring tens of billions for a full conversion. Despite this, the previous government insisted on another study into the feasibility of driverless trains.

In light of the findings, Mayor of London Sadiq Khan confirmed that both TfL and the DfT agreed not to pursue the costly project further, acknowledging that the long-term savings would not justify the upfront investment.