This picture, taken by passenger Martin Stewart, shows the broken cable hanging over the track in Radlett station yesterday.
Severe delays have been predicted on Southeastern, East Midlands Trains and First Capital Connect until the end of the week.
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Some platforms have been taken out of service with disruption expected to continue until the end of the day.
The Met Office has extended its weather warnings for snow and ice to cover vast swathes of the country, including London and the South East.
A total of 270,000 documents is expected to be submitted to the inquiry.