International Journal of Railway Technology Volume 1, Issue 1, Pages 231-247, 2012. doi:10.4203/ijr t.1.1.11 ©Saxe-Coburg Publications, 2012 Wayside Train Monitoring Systems: A State-of-the-Art and Running Safety Implications A. Bracciali Dipartimento di Meccanica e Tecnologie Industriali Università degli Studi di Firenze, Italy Abstract The appearance of railway undertakings in Europe led to an enormous increase in rolling stock operators: mainly in the freight sector. To keep these vehicles under control, and to limit as much as possible the consequences of accidents arising from failures, fires, exceeded gauge, etc., it is necessary to consider the possibility (and the need) to check rolling stock conditions from stationary measuring equipment, i.e. at wayside train monitoring systems (WTMS). After the analysis of the literature on railway accidents, this paper aims to classifying safety-related and maintenance- related train-environment interactions, discussing the implications and the capabilities of existing WTMS systems. Keywords: railways, rolling stock, wayside monitoring, accidents, safety, review. 1 Introduction Safety, regularity and cost effectiveness have been mandatory requirements of railways since they were first invented. It is not surprising that the three mentioned characteristics, in the above mentioned order, were at the basis of all regulations and training every railway system around the world. Today we face a world that has dramatically changed in the last two decades. In Europe: after the Maastricht agreement, the free circulation of people and goods have become (or should have become) a reality that completely changed the approach to national railways as we used to consider them. The “White Paper on Transport” of the European Union introduced a package of measures to revitalise the rail sector through the rapid creation of an integrated European rail network. The objective was to speed up market integration by removing major barriers to cross- border services, guaranteeing a high level of safety on the railways, and reducing costs as a result of greater harmonisation of technical standards in the rail sector. 231 232 A. Bracciali – Int J Railway Tech, 1(1), 231-247, 2012 That document opened the market to new subjects previously unknown (Railway Undertakings, RU [1]) whose only goal was to make a profit from both passenger and freight services. As a counterpart, these new subjects did not have the engineering knowledge and safety culture of previously existing national railways. In general, more traffic means more vehicles, more mileage, increased use and, in mechanical terms, greater potential wear and fatigue problems. Higher efficiency measures also mean fewer personnel for ordinary inspections and checks, and a potentially higher risk of unexpected and undesired accidents arising from catastrophic failures of safety-related components. An improved design of vehicles is certainly possible because more advanced resources are available (finite element codes, experimental stress analysis, etc.), however they are not by themselves sufficient to ensure a priori that the aforementioned accidents cannot happen in practice. For some classes of vehicle, such as freight wagons, actual operational conditions are still largely unknown: i.e. real routes that the wagon will travel on are not predictable (if not for really a few instances), and loads cannot be safely predicted. Unlimited life approach, which was used until a few years ago, is today believed to be too conservative, but the practical applicability of damage accumulation arising from time-varying loads still suffers from the uncertainty of input parameters. An automatic and unmanned survey is necessary to maintain the leadership that the railways still have in terms of safety. This is possible today thanks to the advances in sensor technology, database size, and the computer network distribution throughout the European territory. Both web and satellite communications offer the possibility of checking the status of a network, or a fleet of vehicles, virtually from any position on Earth. This paper focuses on the requirements for wayside train monitoring systems: addressing their potential and limits, and therefore depict where the application is trivial or where it is still a matter of research and development. 2 Train-side monitoring and wayside monitoring Safety can be achieved by monitoring both vehicle and infrastructure conditions. It is, in fact, from the interaction of the two that risks may generate a danger to people travelling on the train, and to people living close to railway lines. When the number of employees was large enough (and computers were still in the cradle), patrolling was the usual way to check the integrity of the railway network. Large efforts were made, starting in the 1960s, with the first Shinkansen monitoring train (called Doctor Yellow) [1]. Nowadays most infrastructure owners have one or more recording trains (see, for instance, the Network Rail New Measurement Train (NMT) [3]; the SNCF TGV Iris 320 [4]; the RFI Archimede; and Y1/Y2 trains [5]): there are also companies that offer diagnostic services by means of measuring trains (see i.e. the Dutch company Eurailscout [6]). These measuring trains have the dual purpose of both reducing the number of people Wayside Train Monitoring Systems: A State-of-the-Art 233 needed to visually check the conditions of the track, and to guarantee that the infrastructure quality level is sufficient to ensure the safe running of trains throughout the network, the latter being a duty of the (state based) infrastructure owner. It can be said that the field of network conditions monitoring, which is outside the scope of this paper, is well established and that a number of competing companies offer complete subsystems including hardware (sensors, signal conditioners) and software (visualization, storage and data management applications) to check track geometry, rail wear, overhead line conditions, and so on. One of the dual aspects of track monitoring is vehicle inspection. This was traditionally carried out in workshops at fixed times or distance intervals, but, for the reasons described in the introduction, this is not automatically done by national railways anymore. With the revision of the Directive on Railway Safety in Europe, the EU introduced the term “Entity in Charge of Maintenance” in 2008 [7]. This “Entity in Charge of Maintenance” must ensure that all wagons assigned to it in the national vehicle registers are serviced in accordance with the regulations in force [8]. 3 Railway disasters analysis and prevention The European Railway Agency has a research project which has gathered information about serious accidents for the period 1990-2009. The project identified 402 serious accidents: of which 385 were not previously known to the ERA (Figure 1). The archive contains fatal train collisions, derailments and fires, level crossing accidents with on-train fatalities, and other accidents with four or more fatalities. For a project brief see [9], while the full document can be downloaded from [10]. In twenty years of service in Europe, there were 100 such disasters with 979 fatalities, and 1343 injured people. Figure 1: Accidents in Europe with five or more fatalities since 1990 [9] 234 A. Bracciali – Int J Railway Tech, 1(1), 231-247, 2012 This official and authoritative source of data classifies accidents in six categories listed below in alphabetical order (for each the total number of fatalities and injured people is reported): • Accident to person caused by RS in motion (fatalities: 24, injured: 3); • Fire in rolling stock (fatalities: 21, injured: 10); • Level-crossing accident (fatalities: 349, injured: 143); • Train collision with an obstacle (fatalities: 32, injured: 120); • Train derailment (fatalities: 269, injured: 417); • Trains collision (fatalities: 284, injured: 650). It is important, for the scope of the present paper, to assess which of these accidents happened because of either track or rolling stock direct failure, or for reasons arising from failures in their interaction. At a first glance, some accident classes are most likely a result of human behaviour (accidents to persons caused by rolling stock in motion, level-crossing accidents); some others to signalling related problems (trains collisions); and some other to infrastructure problems not directly related with track specific features (train collision with an obstacle, as fallen trees, landslides, etc.). There are apparently only two classes which are interesting in this context: fire in rolling stock, and train derailment. Fatalities arising from derailment are 27.4 % of the total number of fatalities; it is, therefore, interesting to look in more detail at the reasons for the most important accidents in this category. Figure 2 shows that the derailments, sorted by the number of casualties, were mostly brought about by reasons which were related not to the direct running dynamics of the vehicles, but to other infrastructure failures, excess speed, or broken components. Avoidable Date Country Place Fats. Inj. Reason with WTMS? 03/06/1998 DE Eschede 101 87 Broken composite wheel No 29/06/2009 IT Viareggio 32 27 Broken axle No 02/12/1994 HU Szajol station 31 54 Switch set incorrectly No 31/03/1997 ES Uharte Arakil station, Pamplona, Navarra 18 40 Speed excess No 05/05/1997 PL Reptowo, Szczecin 12 40 N/A N/A 15/11/1992 DE Northeim 11 0 Fallen steel bar caused derailment Probably Yes 06/03/1998 FI Jyväskylä 10 8 N/A N/A 06/02/2000 DE Brühl 952Speed excess No 12/01/1997 IT Piacenza 830Speed excess No 20/07/2002 IT Messina, Sicily 82Track conditions No 10/05/2002 UK Potters Bar 732Points equipment failure No 21/08/2006 ES Between León and Palencia. 76Speed excess No 30/11/1992 NL Hoofddorp 56N/A N/A 11/09/1994 EL Tithoréa 50N/A N/A 27/02/1995 ES San Sebastian 533N/A N/A Figure 2: Derailments in Europe with 5 or more fatalities since 1990 (data reprocessed from [9]) The biggest ever disaster in modern railways, the Eschede derailment in 1998, was caused by the failure of a “composite wheel”, i.e.