Summary Safety Investigation Report

Transcription

1 Investigation Body for Railway Accidents and Incidents Summary Safety Investigation Report Collision between a work train and the rear of a passenger train Linkebeek, Monday 3 November 2014 December 2015

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3 SUMMARY On Monday 3 November at around 13:14, a passenger train left Braine-l Alleud for Aalst according to the established timetable. The train stopped at its regular stops at various stopping points (including Waterloo, Rhode-Saint-Genèse). After crossing Holleken, the train started up the slope in direction of its stop at Linkebeek. At around 13:24, the passenger train was unable to stop in time and came to a standstill after the major stop signal (green) which was at the end of the platform. Several minutes later, a work train made up of a single locomotive, coming from Monceau, was assigned a route to Schaerbeek. This work train took a portion of the line (L.124) and followed the passenger train. At Holleken, the driver of the locomotive encountered a restrictive double yellow signal (IY-L.1). The study of recordings showed that the driver reduced his speed before passing this signal. He initiated the descent towards Linkebeek at a reduced speed. He braked so as to stop at the next stop signal. Despite the engaging of the emergency brake, the locomotive passed the signal at danger (red) and collided with the rear of the passenger train. The driver of the passenger train immediately sent a GSM-R alarm. At 13:30, traffic was stopped on the line (L124). Twenty passengers were evacuated to nearby hospitals. All passengers (superficial cuts and bruises) left the hospital that day. The train personnel were treated at the scene. There was no damage to the infrastructure. The damage to rolling stock was limited. Zone du début de freinage Repeater warning signal Zone where the driver confirms the restriction of the signal Zone of complete wheel slip (emergency braking) Closed signal Collision Warning signal (double yellow) 3 How the braking of the work train (locomotive) occurred

4 In the hours that followed the accident, the tracks between the stopping points at Holleken and Linkebeek were inspected. The Investigation Body (IB) noted that the upper side of the rail head was extremely clogged up and covered in a black, viscous grime: partially crushed, blackened leaf residue. The slippery condition caused by the leaves on the rails is a complex and multiple problem in which purely physical elements as well as biological factors can play a role: numerous studies have tried to answer the question. A study by Ulf Olofsson and alii 1 has determined the effect of the different forms of clogging present on the track on the coefficients of friction: the coefficient of friction showing the lowest score concerns the rails clogged up with wet leaves. The infrastructure manager has a forecasting procedure thanks to an adhesion index on the tracks and has forecasts prepared by an external service. The model of forecasts used did not allow the adhesion problems that occurred on 3 November 2014 to be predicted. The infrastructure manager has devised a cleaning programme. The frequency of cleanings as well as the location of areas to be cleaned are determined in advance according to experience acquired. The zone between Linkebeek and Holleken was identified as a risk zone and several cleanings take place each week. However, the cleaning procedures did not foresee cleaning of the tracks going downhill. The IB found that the day before and on the day of the accident, adhesion problems were occurring at the scene of the accident and in the area around it; however, they were not all reported by the drivers. In the statistics, we mainly find adhesion problems occurring in traction movements, which often cause delays. These adhesion problems seem to be systematically reported. The statistics contain noticeably less reporting of adhesion problems when braking. 4 1 Tribology of the wheel-rail contact aspects of wear, particle emission and adhesion Ulf Olofsson et alii, Department of Machine Design, KTH Stockholm; Department of Mechanical Engineering, Sheffield University

5 When there is braking associated with adhesion problems, the wheels of a train will slip on the rails. The driving cab of the locomotive was not equipped with a warning system for adhesion problems. Thanks to his experience and knowledge of the stock, a driver should be able to recognise it and should adapt his driving accordingly. The analysis of recordings shows that the train driver was driving safely but that did not prevent adhesion problems under the circumstances on the day of the accident, which was also in a downhill stretch. Adapted equipment and adequate actions could allow the braking power to be restored. An ABS system aims to automatically prevent the wheels from locking up. The locomotive on the work train did not have such a system. The locomotive was equipped with a system for sanding the rails. This is not used during braking: the instructions given during training and the procedures established for drivers can be confusing. Nozzle of the sanding system The Investigation Body has studied the various systems that allowed the consequences of the collision to be limited. The mechanisms for shock absorption as well as the limited speed of the buffering train prevented the passenger train from derailing, the bodywork from being permanently damaged and the passengers from being seriously injured. 5

6 The analysis of the sequence of events, the technical analysis and the analysis of the safety management system carried out with the support of various external experts have allowed conclusions to be drawn. According to the hypothesis retained by the Investigation Body, the direct cause of the collision in Linkebeek was due to the late stopping of the work train due to the very low adhesion between its wheels and the rails, essentially caused by the presence of dead leaves on the tracks. The very low adhesion between the wheels and the rails had the consequence that the work train slipped past the signal at danger. The abnormally deteriorated operating conditions were made possible by the combination of the presence of dead leaves on the tracks and light precipitation at the moment of the accident. The absence of an ABS system on the locomotive, the non-use of its sanding installation and the slope also contributed to the accident. The presence of grease in the contact zone between the wheel and the rail was not proven: the results of laboratory analysis of the samples taken by the infrastructure manager were not pertinent for the investigation: they were not taken from the bearing surface of the track. In any case, the results of these analyses indicate a contamination of the sides of rail head by lubricant from the greasing of the rolling stock flange. 6

7 The Investigation Body identifies three causes that were indirectly responsible for the collision: the lack of cleaning of the tracks on the slope allowed the clogging up of the tracks and the accumulation of this dirt, the lack of reporting by the drivers to the infrastructure manager of the adhesion problems encountered earlier that day, the late identification of the extent of the adhesion problems during the hours and days preceding the accident. As an underlying cause, the Investigation Body points to an incomplete identification of the risks associated with the danger of poor adhesion, in particular the risks of collision due to adhesion problems when braking (downhill). The Investigation Body formulated 5 recommendations for a better identification of adhesion problems and a reinforcement of preventive measures. An additional recommendation is intended to encourage collaboration between railway undertakings and the infrastructure manager so as to consult one another concerning problems of contamination of the tracks by grease. 7

8 RECOMMENDATIONS Generally speaking, the recommendations of the investigation body must be addressed to the Safety Authority (DRSI) and written as goal-oriented. The recommendations do not constitute a prioritisation. It comes down to the DRSI in consultation with the infrastructure manager and the railway undertakings to transform them into «solution-oriented» recommendations. An effective management of the risks is only possible if they put in place a process centred on three basic dimensions: technical component: tools and equipment human component: skills, training, staff motivation organisational component: procedures and methods allowing definition of the relationship between the different tasks. N Observations and conclusions of analysis 1 The adhesion problems on 3 November 2014 were mainly caused by the presence of dead leaves on the track. Recommendation on the direct causes of the accident The DRSI should check that the infrastructure manager manages the vegetation along the tracks so as to avoid the adhesion problems caused by fallen leaves. N Observations and conclusions of analysis 2 The sloping tracks had not been cleaned; as a result the tracks were dirty and the dirt was accumulating. Recommendation on the indirect causes of the accident The DRSI should make sure that the infrastructure manager prepares traceable guidelines for the cleaning of the tracks by taking into account the findings in the report. The DRSI should make sure that the infrastructure manager implements a system allowing the measurement and analysis of the quality of cleaning. The DRSI should make sure that the infrastructure manager improves the efficiency of the forecasting system for the slippery condition (adhesion) of the tracks. 3 The adhesion problems encountered earlier in the day were not reported to the infrastructure manager. The DRSI should make sure that the railway undertakings immediately report to the infrastructure manager the urgent information concerning the adhesion problems. 8

9 N Observations and conclusions of analysis 4 The seriousness of the adhesion problems during the hours and days preceding the accident were not identified in time. Recommendation on the indirect causes of the accident The DRSI should make sure that the infrastructure manager gives instructions to its services in order to respond in a timely manner to adhesion problems. The DRSI should ensure that the railway undertakings and the infrastructure manager cooperate to guarantee an efficient exchange of information. N Recommendation on the underlying causes of the accident 5 The risks of poor adhesion are not clearly identified and monitoring is based on the criteria number of minutes of delay and number of incidents which cause delay. The DRSI should ensure that the infrastructure manager and the railway undertakings jointly identify all the risks associated with adhesion problems and outline concrete objectives for ensuring that the identified risks are managed. The DRSI should ensure that the infrastructure manager and the railway undertakings take the appropriate correctional measures to be able to measure and analyse all the adhesion problems based on criteria allowing evaluation of the true extent of adhesion problems. N Observations and conclusions of analysis 6 The sides of the rail heads were contaminated by the lubricant from the greasing of the rolling stock wheel flange. Recommendation on additional findings The DRSI should ensure that the railway undertakings evaluate the correct operation and the correct adjustment of the greasing system of the wheel flanges. The DRSI should ensure that the infrastructure manager and the railway undertakings identify all the risks associated with the greasing of the wheel flanges and define specific objectives to ensure that the risks identified are efficiently managed. 9

10 Investigation Body for Railway Accidents and Incidents