London bus workers will stage a second 24-hour strike on Tuesday in a row over roster changes.
Members of Unite at Tower Transit walked out after peace talks failed to break the deadlock.
It will be the second stoppage in a dispute involving more than 1,000 drivers, engineers and controllers at three depots across the capital.
Unite regional officer Simon McCartney said: "Our members take great pride in keeping London on the move and strike action is very much the last resort for them.
"We would urge Tower Transit management to start taking a constructive approach and engage in meaningful talks to avoid further disruption."