The railway line between Bristol and Taunton, via Highbridge, is closed due to bridge repairs this week.
Network Rail says the closures are affecting trains running via Bridgwater and will be in place until the early hours of Saturday, as staff renovate four railway bridges.
Staff will also carry out improvements to track drainage, welding and grinding work, as well as installation of new pipe and inspection chambers.
Network Rail says replacement buses will cover all Great Western Railway journeys between Taunton and Weston-super-Mare and it has urged people to check before they travel.
Cross Country services between Bristol and Taunton will continue but will be diverted via Castle Cary, and take longer.
The works include the replacement of the deck, steelwork and masonry repairs, waterproofing and the repainting of the River Brue bridge and work to both the Somerset and Lympsham bridges.
A full replacement of the bridge span and masonry repairs will also be carried out at Middle Drove bridge, with new sections lifted into place by crane.
“This essential engineering work is needed to ensure the continued safe and reliable running of the railway,” Network Rail says. Follow-up work along the line is expected until June.
