Aslef workers at 16 train operators will walk out tomorrow. Separately, members of the Rail, Maritime and Transport union (RMT) will walk out on the Underground both tomorrow and this Friday.
The Transport Secretary accused RMT and TSSA kingpins of refusing to put the current pay and modernisation deal to their members in a ballot because they fear it would be accepted.
Friday has seen Londoners not able to travel on the Underground after Transport for London (TfL) workers represented by the Rail, Maritime and Transport union (RMT) staged a mass walk-out.