On 6 April 2011, an assistant track section manager (ATSM) employed by Network Rail discovered a structure (Bridge 94, on the main line between Birmingham and Gloucester) supporting the track which he believed to be collapsing. He was on site to check a hole in the ballast under sleepers on the down main line, first identified during a routine track inspection eight days previously, which had reappeared despite being filled with clean ballast.
The ATSM arranged for track maintenance staff to attend site during the evening to monitor the track. They discovered that ballast was falling into a watercourse under each passing train, and reported the failure to Network Rail’s fault control. Staff on site arranged an emergency speed restriction, followed by the diversion of trains onto other lines to bypass the failing structure. There were no injuries, but severe disruption continued until after emergency repairs were complete 36 hours later.
Nobody had inspected the part of the structure where the failure occurred since 2001 because neither Railtrack/Network Rail nor their structures examination contractor recognised the need for staff who were trained and equipped to enter a confined space to examine this structure. Consequently the condition of the part of the structure supporting the track was unknown.
RAIB has identified one learning point from this incident: the importance of undertaking reconnaissance visits as an integral part of the planning process for detailed examinations.
RAIB has also made recommendations to Network Rail that focus on improving the awareness of structures which are not easily visible from track level, and improving the structures examination regime.
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.