The firm pleaded guilty to a safety offence following an investigation and prosecution by industry regulator the Office of Rail and Road (ORR).

Network Rail employees Michael Lewis and Gareth Delbridge were working on the track when a passenger train travelling from Swansea to Paddington struck them causing fatal injuries.

The train narrowly missed the a third worker.

The trio were carrying out track maintenance work without site or distant lookout protection to warn them of approaching trains, or a line block which would have prevented trains from travelling on the section of the track they were working on.

ORR’s investigation found systematic and wide-ranging safety failures by Network Rail in its measures to protect those working on or near the line from trains, resulting from inadequacies in its processes and management systems.

These were similar to the findings of ORR inspections in 2018 and 2019, and from other previous incidents, which led the safety regulator to take formal enforcement action to require Network Rail to improve track worker safety.

Since the accident at Margam there has been a step change in the management of track worker safety, with Network Rail almost entirely ending red-zone working when lines remain live during track work.

Richard Hines. HM Chief Inspector of Railways, said: “Our thoughts continue to be with the family, friends and colleagues of Michael Lewis and Gareth Delbridge.  I am deeply sorry for their loss.  The Court has imposed a fine of £3.75m which reflects the nature and gravity of Network Rail’s failings.

“The rail industry needs to do all it practically can to help each worker get home safely every day. Much progress has been made in reducing risk to track workers, with new protections introduced. The industry is committed to seeing these technologies implemented further and faster.

“This will require a relentless, collective, industry focus to continue to drive down risk to ensure that tragic incidents such as this are never repeated.”

Nick Millington, Route Director, Network Rail Wales & Borders, said: “We know that the tragic deaths of our colleagues, Gareth Delbridge and Michael ‘Spike’ Lewis, should never have happened on our railway and that has been reflected by today’s judgment.

“Over the last five years I have met regularly with Gareth and Spike’s families and our thoughts remain with them, and all those friends and colleagues who have been impacted by their deaths.

“Since this tragedy, we have continued to transform the safety of our workforce through the development of new technology and planning tools, which have almost entirely eliminated the need to work on the railway when trains are running.

“Today’s judgment reinforces why safety must always be our first consideration, and we will continue to do all we can to make our railways the safest they can be.”