Strike action means only a limited service will run on Docklands Light Railway over the weekend of the London Marathon.
Members of the RMT union employed by DLR operator KeolisAmey will walk out for four days from 4am on Friday.
Transport for London said limited services will prioritise getting runners in Sunday's London Marathon to the ExCeL centre in London to register for the event and for their supporters to travel to popular viewing points along the 26-mile route.
Millions of pounds are raised for charity at the London Marathon and we don't want to see the thousands of people who have signed up to run, or their supporters, disrupted. We urge RMT and KeolisAmey Docklands to continue with discussions to settle their dispute. If this strike goes ahead, we will work hard to provide as much of a service as possible over the four days with a particular aim of helping runners and supporters get to the starting line on Sunday.
RMT continues to push for a negotiated settlement in a dispute that is about turning the tide on outsourcing and ensuring workplace justice for this key group of London transport workers.