Transport for London (TfL) is advising customers using the Docklands Light Railway (DLR) that further planned strike action by the RMT union will affect services over a four day period starting this Friday. The strike is due to start at 04.00 on Friday 20 April and end at 03.59 on Tuesday 24 April. It has been called by the RMT over a dispute with KeolisAmey Docklands, who operate the DLR on behalf of TfL. Plans are being developed with the aim of operating a limited service over the four days, which coincide with the London Marathon on Sunday 22 April. Where possible, depending on staff numbers, limited services will be prioritised to enable participants in the London Marathon to travel to ExCeL to register ahead of the event, and for runners and their supporters to reach the race line in Greenwich and on the Isle of Dogs on Sunday. However, customers are advised to check the TfL website for the latest information and to plan ahead, looking at alternative options for their journeys. Extra bus services will be deployed along the DLR network over the four days and TfL Travel Ambassadors will be on hand to provide travel information and advice to customers. All other TfL services will be operating as usual, however there will be road closures around the London Marathon route from early Sunday morning. The Jubilee, Central, District and Hammersmith & City lines in East London are expected to be busier than usual and stations including Canary Wharf, Canada Water, London Bridge, Canning Town, Bank and Stratford may be exceptionally busy. Customers are advised to check before they travel and allow extra time for their journeys. Further information on what services may operate will be communicated ahead of the strike and posters, digital boards and announcements in London Underground and London Overground stations will keep customers informed of the levels of service. Mark Davis, TfL's Interim General Manager of the DLR, said: "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. Bus, Tube and rail services will operate as normal and we will have extra buses running along the DLR route. Customers are advised to check before they travel and allow extra time to make their journeys, while our Travel Ambassadors will be on hand to provide information and advice and help keep London moving."