Travel disruptions and delays will affect commuters later today when London Underground staff stage a 48-hour walk out over plans to close ticket offices.
Members of the Rail, Maritime and Transport Workers union (RMT) plan to take strike action from 9pm this evening, returning at 8.59pm on Wednesday.
RMT has been in talks with London Underground (LU) about the plans, which will see 960 jobs being cut.
But Mike Brown, managing director of LU, said: "We will not be diverted from doing the right thing.
"No responsible management can stand by and force customers to pay £50 million a year for services which can be delivered far better and while keeping fares down.”
Mr Brown also said LU has made changes to its proposals after listening to staff over the last eight weeks.
This includes pledging to have a customer service supervisor at smaller stations at all times.
The Times and Independent Series is waiting for a comment from RMT.