Why it matters: The disruption is expected to last all day, affecting thousands of passengers travelling between East Anglia and the capital.
The big picture: Greater Anglia has implemented a revised timetable on several routes, including:
Norwich to London Liverpool Street: One train per hour between Norwich and Colchester
Ipswich to London Liverpool Street: Revised peak timetable
What's happening: Only one line between Colchester and Marks Tey is available, forcing trains to run at reduced speeds and frequency.
Network Rail engineers will be working on the overhead wires throughout the day
Pre-booked tickets for Wednesday will be accepted on Thursday
Ticket restrictions have been lifted
What's next: Passengers are advised to check the Greater Anglia website or app for specific train alterations before travelling.
Travellers whose journeys are delayed by 15 minutes or more may be entitled to compensation under the Delay Repay scheme.
