Network Rail (NR) is facing an unlimited fine after its lawyers said they would plead guilty to health and safety breaches leading up to the fatal Grayrigg train crash.
Margaret Masson, 84, from Glasgow, died from multiple injuries after a Virgin Pendolino London to Glasgow express train crashed on the West Coast Main Line near the Cumbrian village of Grayrigg on February 23 2007.
A further 86 passengers and two crew were injured, 28 seriously, when the 300-tonne locomotive derailed at 95mph after hitting a faulty set of points, with all nine carriages of the Class 390 tilting train coming off the tracks.
The firm's lawyers appeared at Lancaster Magistrates' Court for breaching health and safety law, following criminal proceedings started by the Office of Rail Regulation (ORR).
Network Rail, which is responsible for track maintenance, is facing a charge under section 3(1) of the 1974 Health and Safety at Work Act. Stretcher bars holding the moveable rails a set distance apart when the points are operated failed, causing the train to derail.
Network Rail chief executive David Higgins said later: "The Grayrigg derailment in 2007, resulting in the tragic death of Mrs Masson, was a terrible event. Within hours of the event it was clear that we were responsible, that the infrastructure was at fault, so it is right that we plead guilty. We again apologise to Mrs Masson's family for the undoubted grief this has caused them."
He went on: "While there were faults at hand in 2007, we have been determined to recognise what we got wrong and put it right. An event like this affects everyone in the company, and especially those with responsibility for the track.
"Since the accident, much has changed in the way we plan and carry out maintenance work, with new systems put in place to improve the quality and safety of our railway. We have one of the safest passenger railways in Europe and safety will always be our number one priority."
A spokesman for the Office of Rail Regulation (ORR) said: "Our thoughts are with the family of Mrs Masson and all those involved in this incident. ORR will do everything it can to ensure that the prosecution proceeds as quickly as possible."
The case was sent to Preston Crown Court where NR will face a fine, unlimited in amount, when sentence is passed on April 2.