Temporary closure of West Highland Line will enable essential upgrades
https://www.networkrailmediacentre.co.uk/news/temporary-closure-of-west-hig...
"Engineers will work around the clock from March 16 to complete the project before the line reopens for service on Monday 25 March."
"Buses will also replace trains from Tulloch, Roy Bridge & Spean Bridge stations to Fort William but there will be no services to Rannoch and Corrour during the closure."
So if you're planning on using the line to go walking to/from Corrour or Rannoch during this time, you might want to review your plans.