London Underground says that moving control-room services to Hammersmith will increase capacity on the tube network.
A single control centre is being set up as part of a major modernisation programme. New signalling systems are also being installed on the Metropolitan, District, Hammersmith & City and Circle Lines.
The RMT union's complaints relate to the transfer of Piccadilly Line control-room services to a new centre in Hammersmith.
Transport for London plans to replace a number of separate control centres with a single one from 2017.
The Rail, Maritime and Transport Union says the move will cause job losses - and that there are also issues with rates of pay and the lack of "any meaningful offer for Service Control staff for the Olympic period."