The risk posed by construction activity nearby railway tunnels is under review after a major accident was narrowly averted when two massive construction drills burst through the walls of a tunnel as a train approached.

Islington Gazette: The scene of the incident near Old Street stationThe scene of the incident near Old Street station (Image: Archant)

The Rail Accident Investigation Bureau (RAIB) is looking into the incident on March 8, which took place just north of Old Street station below a building site at 99 East Road.

Just after 10am the driver of a train travelling from Moorgate to Welwyn Garden City reported water was gushing from the roof of the tunnel between Old Street and Essex Road stations.

A second empty train was sent along the line just after 11am to investigate the problem.

But as it slowly approached the area 420m north of Old Street, the driver and the Network Rail mobile operations manager who accompanied him, spotted two large metallic objects which had fallen from a hole in the roof of the tunnel – one of which was touching the live conductor rail.

These were later identified as two two-metre long sections of an auger drill which had penetrated the tunnel lining before falling onto the track.

Immediate checks linked the drilling operation to construction activity at 99 East Road, 13 metres above the top of the tunnel, where developer Protean Developments Ltd was building a seven-storey block, with commercial space on the ground floor and nine residential apartments above.

The RAIB’s investigation will review the information available to those responsible for the safety of the construction activity there, and the way in which the risk created by construction activities near to railway tunnels is currently managed.

The Health and Safety Executive and the Office of Rail Regulation are also investigating the incident.

The Gazette was unable to contact Protean Developments Ltd, and Ms Charlotte Ambrose from Charlotte Ambrose Architects who designed the building said she did not want to comment.

At the time of the incident, train operator First Capital Connect (FCC) managing Director Neal Lawson said: “This is 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.”