Rail infrastructure company Network Rail (NR) has pleaded guilty to breaching safety regulations over the 2002 Potters Bar train crash which claimed seven lives.
A faulty set of points was to blame for the May 2002 crash when a West Anglia Great Northern express travelling from London to King's Lynn in Norfolk derailed just outside Potters Bar station.
Six passengers on the train were killed and more than 70 injured. A pedestrian also died after being hit by debris.
The plea was entered at St Albans Crown Court in Hertfordshire and the case was listed for sentencing at the same court on May 12.
The maintenance company involved was Jarvis while the overall responsibility for the track lay with NR's predecessor company, Railtrack.
Last year, the Office of Rail Regulation (ORR) launched proceedings against Jarvis and NR under the Health and Safety at Work Act.
Both companies were accused of failings over the installation, maintenance and inspection of adjustable stretcher bars which keep the moveable section of the points at the correct width for train wheels.
Earlier this month, the ORR said it was not proceeding with the prosecution of Jarvis which went into administration last year.