Overview

• Engineers ran successful underground trial runs between Northfields and Hyde Park Corner to validate integration of the air-conditioned units.
• Prototype faults with air-conditioning systems and clearance tolerances discovered during depot testing prompted further design work by Siemens Mobility.
• Transport for London now plans for the full fleet of 94 walk-through trains to enter passenger service in the second half of 2026.
• TfL commissioners emphasize that safety and compatibility with existing infrastructure remain top priorities before public deployment.
• London Assembly member Keith Prince has called on the Mayor to disclose the specific issue that caused the year-long launch delay.