Mainline train services between Norwich and London are being severely disrupted due to an earlier train failure caused by the severe weather conditions.
National Express East Anglia (NXEA) said a train had broken down earlier between Manningtree and Colchester causing major delays and cancellations.
A NXEA spokesman said trains were moving slowly but there were delays of up to two hours on services.
Passengers are advised to check their journeys before travelling.
Jonathan Denby, from NXEA, said a number of factors had combined to cause disruption to their services, though the low temperatures were the main cause.
"There have been incidents of equipment on trains freezing up and [the build up of] compacted snow on the trains and then getting into the equipment," he said.
He said icicles were forming under bridges and making contact with the overhead power cables which was causing them to trip out.