Network Rail is to face criminal prosecution over the 2007 rail crash in Grayrigg, Cumbria, that killed one passenger and injured almost 90.
The company, which is responsible for maintaining the track where a Virgin Pendolino train was derailed, is accused of breaking health and safety laws over the crash.
The Office of Rail Regulation said yesterday that it had begun criminal proceedings against the company, two months after an inquest found that badly maintained points were to blame for the crash.
Margaret Masson was killed and 86 people were injured, 28 of them seriously, when all eight carriages of a London-to-Glasgow service left the track at 95mph on 23 February 2007.
Mrs Masson's family placed the blame at the door of Network Rail after a former employee, who was responsible for maintaining the "degraded and unsafe" set of points, told the inquest into her death that he had warned his bosses about the "shambles". David Lewis said his team was overworked, understaffed and poorly equipped to carry out its work.
The Office of Rail Regulation said the proceedings were a result of Network Rail's "failure to provide and implement suitable and sufficient standards, procedures, guidance, training, tools and resources for the inspection and maintenance of fixed stretcher bar points".
The Office's safety director, Ian Prosser, said: "Following the coroner's inquest into the death of Mrs Masson, I have concluded that there is enough evidence, and that it is in the public interest, to bring criminal proceedings against Network Rail for a serious breach of health and safety law which led to the train derailment."
The first hearing is due to take place at Lancaster magistrates' court on 24 February. Network Rail's network operations managing director Robin Gisby said: "Network Rail has not hidden from its responsibilities. The company accepted quickly that it was a fault with the infrastructure that caused the accident. We again apologise to Mrs Masson's family.
"Since the derailment, we have worked closely with the authorities, conducted comprehensive and detailed investigations and made substantial changes to our maintenance regime."
The maximum penalty a magistrates' court can impose for the offence is a fine of £20,000, meaning it is likely the case will be committed to the Crown Court. Last year, Network Rail was fined £3m after admitting safety breaches involving a set of points which led to the Potters Bar crash in 2002, in which seven people died.