Passenger trains were diverted to another branch of the Northern Line while trains were cleared from the Charing Cross branch and that part of the line was closed for most of the day.
A passenger on the train in front of the engineering train described the experience to the BBC. Tom Redfern said: "As soon as we pulled away the driver came on the tannoy and said, 'There is an emergency, will everyone move towards the front of the train'. "There was a ripple of panic. I went from half asleep to a big adrenaline rush. I thought, 'Is this it?'"
The train went through all stations until Moorgate trying to keep ahead of the other vehicle.
Mr Redfern said: "We went full speed. We knew the situation was dangerous because we were going fast. Even by the driver's voice, we could tell it was serious."
London Underground are obviously making a full investigation as to how the incident took place and hopefully we will get to hear the results. I'll be keeping watch on the Rail Accident Investigation Branch site which investigates railway accidents and incidents on UK railways to improve safety.
As you may have also heard the RMT are going on strike in a row over staff cuts and safety. They were quite to make a statement after Friday's incident and said: "This horrific failure comes against a background of a systematic reduction in safety-critical jobs and safety procedures as a direct result of TfL's financial cuts programme. In the light of this morning's events it is essential that TfL call a halt to their cuts plans and bring an end to the dilution of Tube safety."
When the votes for strike action went through Bob Crow said its members would not "sit by while the tracks are turned into a death trap".
At the time London Underground's strategy director Richard Parry accused the RMT of "scaremongering". Now this (Friday 13th) accident has come at a time where Bob Crow must be thinking he's right. Whether there'll be any more public sympathy to the strike remains to be seen.