Rail passengers travelling on lines between London Liverpool Street and Ipswich could face delays on Sunday while track replacement work is carried out.
Greater Anglia has announced that all lines will be blocked between Chelmsford and Colchester and between Witham and Braintree, affecting lines towards Ipswich.
A bus service will replace trains between Ingatestone and Colchester, Witham and Braintree and between Chelmsford and Colchester stations.
A spokesman said a revised timetable would also be operating on Sunday between Ipswich and Norwich.
Shuttle train services are being set up between Marks Tey and Sudbury, Colchester and Clacton, Thorpe-le-Soken and Walton-on-Naze and between Manningtree and Harwich Town stations.
Passengers have been advised to check travel details before setting off on Sunday.
For more information on timetable changes see here.
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