Tube strike set to take place on Tuesday for 48 hours
Passengers face Tube disruption from Tuesday evening until Friday morning if the proposed strike goes ahead next week.
Both the RMT and Transport Salaried Staffs Association are taking part in the action over proposals to close ticket offices.
Union members have said they will walk out at 9pm on February 4.
Transport for London said it will run as many trains as possible but there will be disruption from 9.30pm, running on until the morning of February 7.
"The DLR, London Overground, and other rail services will operate normally but will be busier than usual," said TfL.
"We will enhance our bus services on key routes and you may wish to consider cycling, if possible. Walking may be an option for shorter journeys."
The fall-out stems from the closures of the ticket offices which TfL said would save £750million a year and allow more staff to work on the platforms.
However, around 750 jobs would go in the plans, led by TfL chairman Mayor Boris Johnson.
TSSA's general secretary Manuel Cortes said: "It is now time for Boris to sit down with his staff representatives and negotiate a sensible deal which will protect the safety and security of the travelling public as well as the long-term interests of our members."
Phil Hufton, London Underground's chief operating officer, called the strikes "unnecessary".
He said: "We're committed to implement changes to station staffing without compulsory redundancies and we've been clear that there'll be a job for everyone at LU who wants to work for us and be flexible."
Meanwhile, RMT has announced it was cancelling strike action on the DLR on Thursday after reaching an agreement with operator Serco.