For the next ten weeks, train services for passengers travelling southbound from Cheddington in Buckinghamshire will be disrupted.
Northbound services from Cheddington are unaffected.
The disruption is due to work being carried out on platform 4 at the station, and is required after a maintenance inspection identified that the supporting structure on platform 4 required urgent repairs.
The work is expected to take up to ten weeks to complete.
While Platform 4 is closed, London Northwestern Railway advises that passengers travelling south should use Leighton Buzzard or Tring stations. A rail-replacement shuttle bus service will operate between Leighton Buzzard, Cheddington, and Tring.
Passengers whose journey is delayed by 15 minutes or more because of the platform closure can claim compensation by visiting www.lnr.uk/delayrepay
Passengers travelling to Cheddington from the north should change at Leighton Buzzard, then catch the shuttle bus to Cheddington.
Lawrence Bowman, LNR customer experience director, said: “The safety of our passengers and staff is our top priority and we are working with Network Rail to carry out these essential repairs as quickly as possible.
“London-bound trains will be unable to call at Cheddington on weekdays during the work and we are advising passengers to use Tring or Leighton Buzzard stations instead.
“I would like to apologise to our customers for the inconvenience while these repairs are carried out. I urge anyone whose journey is delayed by 15 minutes or more to claim compensation via Delay Repay.”
James Dean, West Coast South route director for Network Rail, said: “I'm sorry for the disruption closing Platform 4 at Cheddington station will cause, but urgent repairs are needed to make sure we can keep passengers safe.
“We will be working closely with London Northwestern Railway to keep you updated on progress. We urge passengers to check with LNR and National Rail Enquiries for the latest updates on their journeys.”
