RAIL users are being warned of longer journeys this month as work to improve drainage on a Somerset line take place.

Network Rail is carrying out “vital drainage improvements” at Somerton Tunnel, meaning some routes will change – including bus replacement services.

The upgrades aim to reduce the risk from flooding on the line between Castle Cary and Taunton, which the body called “essential work to protect this key South West rail route”.

Running from December 8 to 14, the work around Somerton Tunnel will mean some trains take different routes – and journey times will be longer.

Trains between London Paddington and Plymouth or Penzance will use an alternative route, extending journey times by at least 15 minutes.

Some trains will continue to run between London Paddington and Westbury or Castle Cary from Monday to Friday only.

Trains via Castle Cary for Bristol Temple Meads or Weymouth are unaffected on all dates, while replacement buses will operate between Castle Cary and Taunton on all dates.

Replacement buses also run between Pewsey and Swindon on weekends.

The new drainage system will channel rainwater safely away from the tracks, reducing the flood risk in what Network Rail called a “vital rail corridor between Castle Cary and Taunton”.

Jordan Welsby, GWR station manager for Castle Cary, said: “This is a really important investment in the long-term reliability of our railway. While some services will be affected, trains will still run to London, Bristol, Yeovil and Weymouth from Castle Cary.

“If your usual train is affected, replacement buses will be running – but please allow extra time as bus journeys will take a little longer than the train.”

Jason Pankhurst, Network Rail senior programme manager, added: “Over seven days we’ll be installing a completely new drainage system to take rainwater away from the tracks. This vital work will significantly improve the railway’s resilience in this area and reduce future flood disruption.

“We’re sorry for the temporary inconvenience and really appreciate passengers’ patience while we future-proof this important route.”