Rail passengers are facing major disruption today because of the late finish of improvement works.
Southern Railways has said that the overrun of work delayed rail lines being treated to remove the build up of ice.
This has meant that trains are unable to operate between Lewes and Haywards Heath in both directions, and so buses are operating between Haywards Heath and Lewes.
Passengers travelling towards London from West Coast stations can travel via the Arun Valley line between Barnham and Three Bridges. Passengers from East Coast stations can travel via Eastbourne and Hastings and then via South Eastern Trains services via Tonbridge to London Bridge and Charing Cross stations.
Trains are unable to operate between Horsham and Dorking and also Reigate and Redhill. Buses have been arranged to operate on these routes.
Southern service between South Croydon and Milton Keynes has been suspended passengers should travel via Victoria and Euston.