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Rail Investigation Summary

​This is a collation of some of the world’s railway formal inquiry reports. It includes a brief incident synopsis, along with the main causes and recommendations from each investigation.

Readers may find some of the actions and recommendations useful to their own operations.

Co-ordinated by Greg Morse,Operational Feedback Specialist, RSSB.


UK: Derailment due to a landslip, and subsequent collision, at Watford, 16 September 2016

Czech Republic: Freight train SPAD derailment at Kralupy nad Vltavou station, 5 April 2017

Some of the key issues raised and/or suggested by the stories in this edition:

  • Earthworks
  • Risk assessments
  • Corporate memory retention
  • Driver error (distraction)
  • Lack of train protection
  • Signal sighting

10 August

UK: Derailment due to a landslip, and subsequent collision, at Watford, 16 September 2016

Full report External link

Just before 07:00 on Friday 16 September 2016, a London-bound service struck a landslip at the entrance to Watford Tunnel and derailed. The train came to a halt in the tunnel about 28 seconds later, with the leading coach partly obstructing the opposite line.

Around nine seconds later, the derailed train was struck by a passenger train travelling in the opposite direction. The driver of the second train had already received a radio warning and had applied the brake, thus reducing the speed of impact.

Both trains were damaged, but there were no serious injuries to passengers or crew. However, RAIB notes that, had the first train been derailed only a short distance further to the right, the consequences would have been much more severe.

The landslip occurred during a period of exceptionally wet weather. Water from adjacent land had flowed into the cutting close to the tunnel portal and caused soil and rock to wash onto the track. The site had not been identified by Network Rail as being at risk of a flooding-induced landslip. Such a landslip had occurred at the same location in 1940 External link, also causing a derailment. Drawings from the 1940s relating to a structure subsequently constructed to repair the slope were held in a Network Rail archive, but were not available to either Network Rail’s asset management team or the designers of a slope protection project (which was ongoing at the time of the accident). As a consequence, the project made no provision for drainage.

Both trains were crewed by a driver and guard. The drivers each contacted the signaller to inform him of the accident and request the evacuation of passengers. The guards checked on their passengers to confirm that there were no casualties, and made regular announcements to keep them informed.

RAIB has identified the following key learning points:

  • Staff planning new works should ensure that pre-construction record searches are always undertaken. They can reveal essential safety information such as identifying the full range of functions intended to be performed by existing structures.
  • This investigation shows how the availability of working GSM-R radio equipment, and the prompt use of its railway emergency group call function by train drivers and signallers, can provide vital protection for trains during or following an incident if used immediately.

Action taken

Network Rail plans to undertake a full drainage asset survey. Effective implementation of this work should identify circumstances, such as the face wall at Watford, in which historic records suggest a need to provide drainage at locations where none is currently maintained.

Slope protection works have been completed on the north approach to Watford Tunnel. Loose material has been removed and rock-fall netting installed over the failed area.

Network Rail also intends to undertake some local reinstatement to the drainage in the vicinity of the landslip to better capture and contain water from the third party. Timescales for this work are currently unknown.

Network Rail’s London North Western (LNW) control offices have been instructed to hold an emergency meeting after a forecast for rainfall has been upgraded to amber or red at short notice.

LNW geotechnical and drainage teams have also started a programme to review cutting slopes and tunnel portals to identify any water concentration features and the adequacy of any associated drainage arrangements.


  • Network Rail should implement measures to improve surface drainage (e.g. by provision of a suitable drainage system encompassing the crest), in the vicinity of the 2016 Watford Tunnel landslip. It should also investigate whether it is necessary to take steps to manage sub-surface flows which were observed during this accident and could reoccur during a future event.
  • Network Rail should review, and if necessary, improve its process for identification of localised water concentration features which can channel significant amounts of water onto the railway with the consequent risk of slope failure. This review should include:
  • Using current Network Rail processes to analyse the washout and earthflow risk for the slow lines cuttings at Watford to determine whether this correctly identifies the landslip site as a high-risk location; and
  • Verifying that the process has been applied to all relevant track alignments including those such as at Watford where there are closely spaced multiple alignments.
    • The Rail Delivery Group (RDG), in conjunction with RSSB, should:
  • Commission research into the ways in which guidance can be provided to derailed trains. This should include consideration of:
  • How the design of bogies and bogie mounted equipment can assist in limiting the lateral deviation of passenger trains during a derailment;
  • Practice in other countries (e.g. Japan);
  • How specially installed infrastructure features can achieve the same effect at high-risk locations
  • Potential design requirements for the retention or enhancement of such features on new trains or infrastructure; and
  • The potential benefits and drawbacks of such measures.
  • If such features, whether existing or additional, are shown to have a net beneficial effect in reducing risk by limiting lateral deviation, RDG/RSSB should:

  • Share this information with the relevant Standards Committees; and
  • Record and disseminate the design requirements with a view to their incorporation into future standards.
    • Siemens, in conjunction with the relevant rolling stock owning companies, should review and improve the physical security and/or location of emergency equipment1 carried in driving cabs
    • Network Rail should improve emergency arrangements for its infrastructure by:
  • Reviewing with relevant organisations and, where appropriate, improving its processes in order to minimise the time taken during emergencies to contact organisations providing fire and rescue and ambulance services; and
  • Considering and, where necessary, implementing liaison with the local fire and rescue service including participation in joint site inspections at access gates which may need to be used by the emergency services where appropriate.
  • 29 August

    Czech Republic: Freight train SPAD and derailment at Kralupy nad Vltavou station, 5 April 2017

    Full report External link

    At 15:22 (local time) on 5 April 2017, a freight passed at signal at danger at Kralupy nad Vltavou station, entering a section of line occupied by a regional passenger train. There were no reported injuries.

    The investigation report noted that the driver had been distracted by watching persons traverse a level crossing. It added the absence of train protection as a contributory factor, although the recommendations imply an additional signal sighting issue.


    • The Czech National Safety Authority (in co-operation with the infrastructure manager) should replace the ground-mounted signal (see above) with a postmounted signal to improve sighting.

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