sentences:  The latest conversion was announced in July 2013 on the Gospel Oak to Barking Line.The National Union of Rail, Maritime and Transport Workers (RMT) challenged the move, claiming passenger safety would be compromised.Transport for London replied that at the time the East London Line, already one-man operated, has one door-related incident for every seven million passengers, while the section of the network which currently uses conductors has one door-related incident for every four million passengers.