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.
More top news
London's Rio Ferdinand has announced his retirement as a professional footballer.
Two thousand women, and one very excited Barbara Windsor, put on their trainers today in a bid to raise money to fight cancer.
Two men have been jailed after a semi-automatic submachine gun was found hidden in a shoe box in a kitchen.