Report 17/2017: Partial collapse of a wall onto open railway lines, Liverpool
Partial collapse of a wall onto open railway lines, Liverpool, 28 February 2017.
At about 17:38 hrs on Tuesday 28 February 2017, 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 fell into the cutting in at least two separate falls, the last of which occurred at 18:02 hrs.
No trains were struck by the falling debris and there were no injuries. The overhead wires on some of the tracks were brought down and all lines were blocked by the debris. This led to severe disruption of train services. The lines were closed until 8 March 2017, during which time repairs were made to the wall, the overhead electrical supply system and the track.
The investigation found that there had been developments on the leased property adjacent to the cutting, which included the addition of a soil embankment immediately 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. The increase in ground level caused the wall to be subjected to higher loading. Heavy rainfall may also have played a role in triggering the collapse. 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 did not have a suitable risk prioritisation process in place for retaining walls, such as the one that collapsed, that have a high potential safety consequence in the event of a failure.
The RAIB has made two recommendations to Network Rail. The first relates to being aware of those of its walls which have a potentially high safety consequence in the event of failure. The second is for Network Rail to review its assessment procedures for such walls, the use of open source data to identify changes in land use, and the provision of information on property boundaries to structures examiners.
Animation
This video is a 3D model created from aerial images captured on the day following the wall collapse:
3D model of wall collapse close to Liverpool Lime Street station
Response to recommendations:
- RAIB will periodically update the status of recommendations as reported to us by the relevant safety authority or public body
- RAIB may add comment, particularly if we have concerns regarding these responses.