Colour-blind Tube drivers can now take the controls on one of the capital’s busiest lines, after London Underground lifted its long-standing bar on staff with colour vision deficiency working the Northern line.
The rule change means applicants who fail the traditional red-green colour vision test are no longer automatically excluded from the driver’s cab on the line, which runs from Morden in the south to High Barnet and Edgware in the north. Sucha Singh has become the first driver with red-green colour vision deficiency to work the line.
Until now, colour-blind staff were shut out of driving duties across almost the entire Underground. The sole exception was the Jubilee line, where a closely monitored trial beginning in 2019 allowed a small number of drivers with colour vision deficiency to operate its automatic trains, which no longer depend on old-style red and green lineside signals.
Transport bosses say the Northern line can now follow the same path because its signalling is being modernised. As older colour-coded systems are phased out and replaced, the medical requirement to distinguish red from green at a distance has become redundant for drivers on the line.
Key facts
- What’s changed: London Underground now permits train drivers with red-green colour vision deficiency on the Northern line.
- First through the cab door: Sucha Singh.
- Why now: signalling upgrades have phased out the old colour-coded systems.
- Previously: only the Jubilee line admitted colour-blind drivers, on a trial basis since 2019.
- Announced: 28 September 2026.
How the old rule worked — and why it is changing
For decades, would-be Tube drivers had to pass strict colour vision screening, including the familiar Ishihara test of coloured dots. The reason was straightforward: much of the railway’s safety signalling was built around red, green and yellow lights, and a driver who could not reliably tell red from green was judged a safety risk.
The Jubilee line was the first to break the mould. Its move to automatic train operation removed the reliance on red and green aspects, and London Underground began a small, carefully supervised trial letting colour-blind staff drive there. Research published in January 2025 by the Rail Safety and Standards Board then recommended fairer, more practical colour vision testing across Britain’s railways.
The Northern line’s own resignalling has now reached the point where the same logic applies. With modern signalling doing the work that coloured lights once did, picking out red from green at distance is no longer the safety-critical skill it was. Medical standards have been updated to match, while the rest of the fitness requirements for drivers remain unchanged.
From ban to breakthrough: a short history
- 2019: London Underground launches a closely monitored trial allowing colour-blind drivers on the Jubilee line, whose automatic trains no longer rely on red and green lineside signals.
- January 2025: the Rail Safety and Standards Board publishes research recommending fairer, more practical colour vision testing across Britain’s railways.
- 28 September 2026: the initiative is extended to the Northern line as older signalling systems are phased out. Sucha Singh becomes the first driver with red-green colour vision deficiency to work the line.
A wider pool of drivers
The change is expected to widen the pool of potential drivers at a time when the Underground is recruiting. It also ends what equality campaigners described as an anomaly: colour vision deficiency, which affects around one in twelve men, was no barrier to holding a driving licence or working in many other safety-critical jobs, yet it kept people out of Tube cabs.
For passengers, little will change day to day — the trains, timetables and staffing levels stay the same. But the decision marks another step in the slow modernisation of the network, where ageing signalling is gradually giving way to computer-controlled systems. The Piccadilly line is next in line for renewal, with its new trains unveiled in Berlin ahead of a 2027 debut and a first look at the 113-metre fleet already public.
The move also forms part of a wider shake-up at the transport authority, which has launched a year-long pilot to bring station cleaning in-house across the Tube, bus and other stations.
