Tunnel failure put Brighton and Hove train commuters lives at risk

Thousands of commuters from Brighton and Hove were put at risk by poor maintenance in the Balcombe Tunnel, according to an official report.

The Rail Accident Investigation Branch of the Department for Transport said that a roof structure was hanging inches above fast-moving trains after bolts or studs had worked loose and fallen out.

Its report said that missing bolts meant that beams or girders, which were holding up a large tray to keep water off the electric rail, were at risk of striking a train.

Loose bolts could have worked free, smashing the driver’s window with potentially “severe consequences for the driver”.

And if more bolts had fallen out or loosened further, the huge drip tray could have crashed into a train.

An anonymous railway engineer told the BBC that the result could have been fatal.

One 40ft-long steel tray had 18 bolts – or one in five – missing and a further five were loose. A further 28 bolts in the tunnel had loose or missing nuts.

The official report said that one of the beams was hanging just a foot above passing trains. But the estimate made “no allowance for movement of the structure under the aerodynamic loading caused by passing trains so the actual clearance was probably less than this”.

The report said: “It is probable that the end connections of further beams or possibly other parts of the catchment tray structure would have failed if aerodynamic loads had continued to be applied by passing trains.

“The failure of another connection would have resulted in greater deflection and might have caused partial collapse of the structure.

“If a transverse beam had deflected sufficiently to have been struck by a train, it is probable that the beam would have detached from the structure, creating significant risk to trains.

“A stud of this size hitting the windscreen of a train travelling at 90 mph would also risk severe consequences for the driver.”

The problem was highlighted a number of times but nothing was done until a maintenance crew from Brighton raised the alarm early on the morning of Friday 23 September 2011.

The line was closed immediately, causing rush-hour chaos and preventing commuters from being able to travel by train to and from London.

Emergency repairs were carried out in the 170-year-old tunnel, which is more than half a mile long and has a speed limit of 90mph.

The Rail Accident Investigation Branch report criticised Network Rail. The track and infrastructure company has employed an insufficiently qualified and inexperienced engineer and had given him inadequate support.