Trains between Gloucester and Swindon are being disrupted after a landslip near Stonehouse blocked the lines.
Buses will replace trains with journey times being extended by up to 45 minutes.
Network Rail said engineers were currently on site to assess the damage and were working towards reopening the lines.
A spokesman said he expected it would be "a couple of days" before services completely returned to normal.
- Published3 January 2014
- Published1 January 2014