During the evening of 14 November 2009, the foundations of a Victorian bridge carrying the railway over the River Crane near Feltham in West London failed without warning, causing part of the bridge to subside. The first indication of a problem was a track defect reported by a train driver crossing the bridge on the up line. Track maintenance staff, called to the site, immediately blocked the up line to all traffic when they became aware of a serious defect with the bridge. The down line was blocked shortly afterwards.
A total of 21 trains crossed the failing bridge between the first report and closure of the line. There was no derailment and no injuries occurred.
The immediate cause was that the east abutment of bridge 48 was undermined by scour - the removal of material by the action of flowing water.
The causal factors were: the obstruction of the watercourse, which channelled the flow towards the east abutment, increasing its velocity and making it more likely that scour would occur; Network Rail being unaware of the obstruction and therefore not taking action to mitigate the risk of scour; and the vulnerability of the east abutment of the bridge to undermining by scour.
A contributory factor was the lack of a mechanism to encourage members of the public who were aware of the obstruction to report it to Network Rail.
RAIB has made five recommendations to Network Rail concerning the management of structures, and one recommendation to the Environment Agency concerning notification to railway infrastructure owners when obstructions are found against a structure.
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.