Network Rail is being urged to put more safety measures in place following the partial collapse of a wall near Liverpool Lime Street this year.
The Rail Accident Investigation Branch (RAIB) has released its report into the 28 February incident, which prompted the closure of train lines at the site until 8 March.
At around 5.38pm on the evening of the incident, part of a wall at the top of a cutting 20 metres above the four-track railway line between Liverpool Lime Street and Edge Hill stations collapsed.
Around 170 tonnes of masonry and other debris are said to have fallen into the cutting in at least two separate falls, the last of which occurred at 6.02pm.
During the incident no trains were struck and there were no injuries, however overhead wires on some of the tracks were brought down and lines were blocked which prompted severe disruption of rail services.
According to the RAIB, investigators found there had been developments on the leased property next to the cutting, which included the addition of a soil embankment behind the top of the wall.
A small portion of the developed land was owned by Network Rail and was not part of the leased property.
With the increase in ground level causing the wall to be subjected to higher loading, and heavy rainfall also having potentially played a part in triggering the collapse, the RAIB suggests that information recorded by Network Rail during its routine examinations was “insufficient to detect the developments on adjacent land and the infringement of its property”.
The investigation also found that Network Rail didn’t have a suitable prioritisation process in place for retaining walls that have a high potential safety consequence in the event of a failure.
The RAIB is now recommending that Network Rail increases awareness of such walls, and also reviews its assessment procedures of them, along with the use of open source data to identify changes in land use and the provision of information on property boundaries to structures examiners.
Simon French, the RAIB’s chief inspector of rail accidents, says: “The signs that a dangerous situation was developing had been there for a long time. Network Rail’s examination system did not pick up the significant changes that were taking place behind the wall due to earth moving activities undertaken by the occupier.
“Similar changes in land use can occur anywhere, especially in areas of urban regeneration. Although I recognise that it can be challenging for the railway industry, it is vital that Network Rail carries out regular and effective checks for activities on its boundaries that may endanger the integrity of its structures. Changes in technology mean that tools, such as aerial surveys, to improve the way in which such information is gathered and analysed, are now readily available.
“RAIB has made recommendations for the railway industry to put in place systems that will reliably detect threats to high risk structures, and cause prompt and appropriate action to be taken, to avoid a danger to the line. I hope that this investigation will result in a significant change to the way that the railway manages risk from its neighbours.”
Responding to the report Priti Patel, head of safety for Network Rail’s London Northern Western business, says: “Safety is our top priority. The RAIB recommends improvements which we will carefully consider.”