Passenger rail services connecting towns outside London are suffering severe delays after a power cable came down in Essex on Monday evening.
Network Rail engineers are working on the line, which connects Norwich, Ipswich and London.
Engineers will add weights to the supporting struts of the overhead power lines, maintaining line tension throughout various weather conditions.
Network Rail said it hopes to have the work completed by 20.00 BST.
In a statement, the company said it was investing ВЈ150m in renewing 30 miles of overhead power lines between Liverpool Street station and Chelmsford.
Reduced services have been running out of Liverpool Street station for two days.
By staff writer
