There is disruption on the Greater Anglia line between Liverpool Street and Norwich due to a signalling problem.
Trains are currently unable to run through Colchester.
Replacement buses are in service between Witham and Ipswich, and Colchester and Clacton.
Abellio, who run the Greater Anglia rail line, has been named Train Operator of the Year at the annual national Rail Business Awards.
Greater Anglia train operator Abellio says it's made real steps in customer service and punctuality in its first year in charge.
Greater Anglia have apologised for the delays that have disrupted services today