THE Tamar Valley Line between Plymouth and Gunnislake will be closed Monday to Friday, May 1 to 5 and May 8 to 12 inclusive, to allow Network Rail to undertake essential maintenance work. The normal rail service will operate at weekends. While these works are being undertaken First Great Western will operate a special bus service, departing at times differing from the normal rail services. Customers are advised to check before travelling and to leave extra time for their journeys.