It happened minutes after a separate signalling problem on the same line left passengers stranded in one train for 50 minutes and another for 40.
The faults affected the Central Line on Tuesday morning and lunchtime.
The first breakdown – involving a signal at White City – led to the Central Line being suspended from Marble Arch to North Acton from 1115 to 1200 GMT.
Two trains were stuck outside White City station as a result.
After 40 minutes one was moved to Shepherd's Bush station, where passengers were allowed to leave, and after 50 minutes the other was taken to East Acton.
via BBC News