Faults with railway bridges and tunnels could go undetected due to a backlog of safety inspections, a regulator has warned.
The Office of Rail and Road (ORR) said it has ordered Network Rail to make more progress in conducting overdue assessments of structures.
Failing to complete evaluations at required intervals “could lead to a safety issue” as faults go undetected or investigated, according to the ORR.
The ORR has been closely monitoring Network Rail’s progress in clearing the backlog of structure examinations since 2021.
It said in a statement: “Despite some pockets of good practice, overall there has been limited progress and some regions have seen the backlog increase.”
Network Rail has agreed to provide the regulator with a plan for dealing with the issue by the end of June.
Inspections of the condition of infrastructure such as bridges, tunnels and culverts, structures that allow water to flow under railway track, are required to ensure they are working as designed.
An inquiry by the Rail Accident Investigation Branch into a fatal train crash in Stonehaven, Aberdeenshire in August 2020 found the failure to ensure inspections were carried out on a drainage system contributed to engineers not identifying a construction fault which led to debris being washed onto the track and causing the derailment.
ORR chief executive John Larkinson said: “There are over 70,000 structures on the rail network, so we understand the scale of the job of inspecting these assets.
“Equally, we know this requires clear, robust and systematic examination plans, but previous attempts to get on top of the backlog of work have failed.
“Network Rail has accepted the need to do better and it must now deliver against the agreed workplan to clear the backlog.”
Network Rail safety and engineering director Martin Frobisher said: “Since the ORR first raised this matter in 2021 we have been developing and enacting recovery measures to ensure structure examinations are up to date.
“Between February and April 2023 there has been a 9% improvement in examination non-compliance.
“We recognise there is still work to be done to build on these improvements and we are liaising closely with the ORR to get back on track.”