Major rail disaster narrowly averted after two huge construction drills burst through tunnel wall Train driver noticed water pouring down onto the roof of his train Train sent to investigate stopped just as drills penetrated tunnel ahead Rail staff averted a possible major disaster today when two huge construction drills came through a tunnel wall on a major commuter route. The driver of a train from Moorgate in London to Welwyn Garden City in Hertfordshire saw muddy water pouring on to the roof of his 10.02am First Capital Connect (FCC) train north of Old Street station. He reported the incident and all rail services were stopped. Two construction drills came through the tunnel of the route from Moorgate to Welwyn Garden City A Network Rail (NR) mobile operations manager went to investigate the problem on board a special empty train from Moorgate at 11.05am. As the train approached at low speed, two large piling drills came through the skin of the tunnel of the Moorgate to Finsbury Park Northern City line. The train stopped in time but the driver was left shaken. The rail route, used by two million City workers every year, was closed for the incident to be investigated and for repairs to be carried out. The incident happened north of Old Street on the Northern City line from Moorgate to Finsbury Park. British Transport Police visited an office construction site above the line and the Rail Accident Investigation Branch were notified. FCC managing director Neal Lawson said: 'This was a serious incident that could have ended very differently had it not been for the vigilance and prompt reporting and actions of our drivers. We carry two million people a year on the Northern City Line and whoever is responsible for this must be held to account. Meanwhile, we have published details of alternative travel arrangements and are urging our passengers to check www.firstcapitalconnect.co.uk for the latest news but the line will be out of action for the rest of the day at least. NR said specialist tunnelling contractors had been sent to the scene to assess the damage. NR route managing director Phil Verster said: 'Our engineers are on site assessing the damage and we will restore the railway as soon as possible but unfortunately the line will remain closed for the rest of the day.' During tonight's peak, FCC services were ran in and out of King's Cross or Finsbury Park instead of Moorgate. Just two services had to be cancelled but six had to start from Alexandra Palace. The line is normally closed at the weekend and engineers will be working to reopen it in time for Monday morning's service.