Underground bosses are warning next week's two-day strike could cause disruption over four days.
Members of the RMT and TSSA unions are expected to stop work for 48 hours at 9pm on Tuesday.
Some late night services are likely to be hit before the full impact of the strike takes effect on Wednesday and Thursday. And there could be some lasting disruption during Friday morning's rush hour.
The dispute is over the planned closure of most Underground ticket offices with the loss of 950 jobs.
Transport for London is planning extra bus and river services but many commuters will face a difficult journey. RMT and TSSA members make up almost 50% of London Underground's workforce. Talks to try to settle the dispute continue at the conciliation service ACAS.