Formal Inquiries

Sutton Common report and recommendations

Rail Safety and Standards Board (RSSB) has issued its formal inquiry report into the circumstances that led to the derailment of the 1201 hrs Luton to Wimbledon passenger train near Sutton Common station on 31 August 2004.

The formal inquiry was convened under independent chairmanship and included representatives on the panel from the involved parties. As with all such inquiries the panel's task was to establish the immediate and underlying causes of the accident and make recommendations to prevent or reduce the risk of recurrence.

Sequence of events

Work to renew both tracks between Sutton and Wimbledon Chase started on 6 August 2004 and both lines were re-opened to normal traffic at 0503 hrs on 31 August 2004.

At 1342 hrs on 31 August 2004 the 1201 hrs Luton to Wimbledon Thameslink service, travelling at 37.5mph, became derailed on the Up Line between West Sutton and Sutton Common. After the line was blocked and the electric traction supply isolated the passengers were led safely the 150 metres to Sutton Common Station by the driver.

Following investigations and re-railing the line was re-opened the next day but there followed a number of closures in the following week due to on-going track problems.

Conclusions

Basic cause
The train derailed because the track alignment was not fit for the speed of the train (37.5mph within the current permitted speed of that section of line- 40 mph). The signaller failed to reach a clear understanding with the driver of the train on the need to examine the line whilst proceeding at caution and being prepared to stop.

Underlying causes
There was no satisfactory competence system for assessing signallers on non-routine or emergency situations.

No information about critical rail temperature or stress free temperature had been passed to the maintenance organisation. As a result of this there were no watchmen in place nor any emergency speed restriction at the time of the derailment.

The tamping of the track subsequent to de-stressing reduced the track’s lateral stability and invalidated the de-stressing. This stability was further reduced by inadequate ballast and lack of gluing. There was no process for controlling alignment and recording or reporting the invalidation of de-stressing.

Recommendations

The report makes recommendations for improvements in a number of key areas and these are summarised as follows:

• Produce and introduce a process for planning and implementing major projects and investment track renewal work.
• Review new Balfour Beatty Rail Services procedure for planning, monitoring and carrying out work and consider adopting it or a modified version for national use.
• Review new Balfour Beatty Rail Services procedure – Assessment of track for traffic – with a view to adopting it or a modified version nationally.
• Provide and implement a process for defining and controlling geometry on curves during track renewals.
• Define permanent way renewal technician competence requirements and introduce training and competence assessment processes to ensure the requirements are met.
• Review of the derogation that permits a range between 21- 27°C for natural de-stressing with a view to removing this range for new installations.

RSSB has issued a full copy of the report to each member of the Railway Group and the other organisations involved in the accident. All recipients of the report need to review the findings and recommendations and take actions where appropriate to address identified deficiencies within their own systems. RSSB will track the industry's response to this report.