Calculating the Exploitation Costs of Trains in the Spanish Railways

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May/June 2013 Copublished by the IEEE CS and the AIP 1521-9615/13/$31.00 2013 IEEE 89C o m p u t e r S i m u l a t i o n sEditors: Muhammad Sahimi, moe@iran.usc.eduBarry I. Schneider, nsfphyman@gmail.comand Gabriel Wainer, Gabriel.Wainer@sce.carleton.caCalCulating the exploitation Costs of trains in the spanish railwaysBy Eugenio Roanes-Lozano, Antonio Hernando, Alberto Garca-lvarez, Luis Mesa, and Ignacio Gonzlez-FrancoO perating the Spanish railway network is quite complex; it has several components to take into account, including two dif-ferent track gauges, two electrification systems, and four families of signal-ing systems (this doesnt include the narrow-gauge network, which we arent counting here). The Spanish railway infrastructure company is called Adif, and the passenger trains (and most of the cargo trains) are operated by Renfe Operadora.The Fundacin de los Ferrocarriles Espaoles (Spanish Railways Foun-dation) commissioned our research group to develop a computer tool that lets users comfortably navigate among these complexities. The correspond-ing software simulation package, called RutasOptiRed, was developed in 20102011, and was recently sum-marized in a previous article in CiSE.1 RutasOptiRed makes decisions easier regarding routes, rolling-stock selec-tion, and future infrastructure or vehicle investments.The Fundacin de los Ferrocarriles Espaoles was so happy about the package that we were given the oppor-tunity to develop its extension (Rutas-OptiRed-II) to treat the computation of consumption, emissions, and ex-ploitation costs for the different pieces of rolling stock. We developed this extension in 20112012, and present the results here. We detail the meth-odology of the calculations performed by the new package elsewhere.2,3Basic Information about the PackageBefore we detail some of the work we accomplished in the RutasOptiRed-II extension package, the following are some of the parameters that we had to consider. For information compar-ing how our system handles the com-plexities of the Spanish railways many components in contrast to other inter-national railway configurations, please see the sidebar Some Technical Spec-ifications of Railway Networks.Antecendents of This WorkAs summarized in the previous ar-ticle about RutasOptiRed,1 the Span-ish Railway Network managed by Adif is really complex (see Figure 1). First, the Iberian track gauge has tradi-tionally been 1,668 mm, while the new high-speed lines are being built in the so-called standard gauge (1,435 mm), and some lines are dual gauge (they have three rails). Moreover, two dif-ferent electrification systems are im-plemented: 3 kilovolt direct current (3 KV DC) for conventional lines and 25 KV alternating current (AC) for high-speed lines (1.5 KV DC is used in neighboring France, where the 25 KV AC is also used). Finally, four completely different families of sig-naling systems are used (and within each family, multiple versions exist).To avoid causing passenger trans-fers, different pieces of dual-gauge, multisignaling, bivoltage, trivoltage, and even hybrid rolling stock (Class 730)4 have been developed. There are appropriate devices, called cambiadores de ancho (gauge changeovers),5 that have been installed at certain junc-tions, to allow these dual-gauge trains to pass from the new network to the old one and vice versa.As detailed in our previous CiSE article,1 RutasOptiRed was able to compute accurate schedules for the different types of trains in a complex railway network, such as the Spanish one. It could look for the best route for a train, or the best train from an ori-gin to a destination passing through or stopping at other stations. The Spanish Railways Foundation ob-tained the information regarding the network and the characteristics of the rolling stock from its databases and Adifs comprehensive annual reports.6The package has a high rate of ac-curacy. For instance, RutasOptiRed package predicts a 6-hour 20-minute travel time for a series 730 hybrid multi ple unit in the MadridA Corua route (see Figure 2), while the real t ravel t ime on 31 October 2012 ranged between 5 hours 59 minutes The Spanish railway network has two different track gauges, two electrification systems, and four families of signaling systemsand the rolling stock includes hybrid trains. The new, extended package presented here finds the timings and best route for any piece of rolling stock and computes its consumption, emissions, and exploitation costs.CISE-15-3-CompSims.indd 89 6/7/13 3:55 PMC o m p u t e r S i m u l a t i o n s90 CoMputing in SCienCe & engineeringSome Technical SpecificaTionS of Railway neTwoRkSThe original RutasOptiRed package and its extension RutasOptiRed-II are completely independent from the network and the rolling stock of the Spanish railway system, and therefore could be applied to any other railway infrastructure network (with one or two track gauges) and any train operating company. Neverthe-less, the package is distinguished by its ability to deal with complex scenarios such as the Spanish railway system.1RutasOptiRed and its extension could clearly be used in a standard, single-gauge, single electrification system network, but then it wouldnt be so eye-catching. Re-garding track gauge (see http://en.wikipedia.org/wiki/Broad_gauge),2 the so-called standard gauge (1,435 mm) is the most commonly used: Continental Europe (except Finland), Britain, and North America have adopted it for the vast majority of their railway lines. But problems arise due to the use of different track gauges in different places around the world.For instance, the Spanish and Portuguese railway net-works use a broad track gauge usually denoted as Iberian gauge, which is 1,668 mm (formerly 1,672 mm) in Spain and 1,664 mm in Portugal (theyre compatible). But the new Spanish high-speed lines are built using the standard gauge (the first one, for MadridSeville, was inaugurated in 1992).3 Also the network of Spains northern neighbor France uses the standard gauge.During the tsarist era, Russia constructed its railway net-work with a track gauge of 1,524 mm (that was changed in the 1960s to 1,520 mm). This decision affected all the ter-ritories that then belonged to Imperial Russia, which have inherited this broad-track gauge (for example, Finland, Lith-uania, Latvia, Estonia, Ukraine, Belarus, and Kazakhstan).Japan has a situation similar to Spain. The traditional net-work was built in the narrow 1,067 mm track gauge, and meanwhile the high-speed lines have been constructed us-ing the standard gauge (the first one, Tokaido Shinkansen, between Tokyo and Osaka, opened in 1964).In Australia, three different track gauges can be found: 1,600 mm (also used in Ireland), the standard gauge, and the 1,067 mm gauge.When it comes to dealing with geographic variability, different track gauges affect both passenger and freight traffic. The traditional method for through-operation, is to raise the coaches or wagons and exchange the axles or bogies. For instance, this is the process followed for freight traffic at the border between Spain and France or between Poland and the countries that once belonged to Imperial Russia.To contend with such issues, several countries (includ-ing Japan) have track-gauge changeovers and dual-gauge rolling stock. For instance, the SUW 2000 is a Polish track-gauge changeover installed in 2003 at two routes between Poland and Lithuania and the Ukraine (that can be used by specific rolling stock).and 6 hours 14 minutes. The best route follows the NW high-speed line till beyond Segovia, turns West to the conventional line through Zamora and Ourense, and uses the new high-speed section Ourense-Santiago be-fore reaching A Corua.Goals of This WorkOnce we developed the original Rutas-OptiRed package, it was clear to us that the next step was to use the appli-cations data to evaluate the economic, energy, and environmental issues asso-ciated with each train and its route(s).The parameters chosen and the formulas used are adaptations to the Spanish case developed by Al-berto that can be found elsewhere.2,3 Garca-lvarezs works were based on Adifs annual reports data,6 and the methodology proposed in these works was assumed by the International Union of Railways (UIC) for comput-ing railway exploitation costs. There isnt much literature on this very spe-cific topic, but we do have a few re-lated references,711 and a simplified introduction to the topic (including an interesting comparison of exploitation costs per km) in different countries can be found at www.ferropedia.es/wiki/Costes_del_ferrocarril:_servicios.We should mention that in this extension of the package (RutasOpti-Red-II), only passengers traveling from the origin to the destination of the train are considered (that is, passengers boarding and getting off at intermedi-ate stations arent taken into account).Data File ChangesBecause of additional considerations (such as economic, energy, and envi-ronmental issues), we examined the current data with new parameters and collected more data about the trains, stations, and lines (see Figure 3).New Simulation ParametersThe parameters we considered in the GUI of the packages first version were origin, destination, stops (optional), sta-tions in the desired route (optional), and the kind of train/all trains/best train.The new parameters we consid-ered in the extension arePMAthe expected average use (of the trains), expressed as a per-centage (for instance, 70 percent);FrDthe design frequency (for instance, 6), which is an initial ap-proximation to the frequency of the trains, not the final datum;mrotthe rotation minutes (for in-stance, 45);PPthe suggested price for the ticket (for instance, 35); andCISE-15-3-CompSims.indd 90 6/7/13 3:55 PMMay/June 2013 91viaj (v iajero is the Spanish for traveler)the expected number of origindestination passengers per year.Infrastructure and Station File ChangesPart of changing the way that we collect and store data to include new parameters involves changing the infrastructure file so that it has one more column: choosing the section (A1, A2, B1, or C1). This is a classification established by Adif for economic purposes, and it deter-mines the usage fee per kilometer (km) to be charged for trains using that line.The stations file also has another column: the rank of the station (E1, E2, E3, E4, and E5). This is a classi-fication established by Adif for billing purposes, too, and will determine the amount charged per passenger board-ing a train at the station.Train File ChangesThe train file now has 11 more columns: cfthe fixed cost per seat and min-utes of rotation;CV2the second variable cost that were considering (per minute and seat);CVDthe variable cost per km and seat (energy) using diesel traction;CVEthe variable cost per km and seat (energy) using electric traction;CV1A1, CV1A2, CV1B1, and CV1C1the four columns that take into ac-count the first variable cost regarding the aforementioned section types A1, A2, B1, and C1 (per km and seat);EDpkmthe energy consumed per km working in diesel traction;EEpkmthe energy (in kilowatts-hour, or kWh) consumed per km working in electric traction (kWh/km); andPLTthe number of seats in the train: PLT.We should further explain that the CV1 costs are the amounts charged by the company managing the net-work (Adif ) to the operating company (Renfe) according to the type of line. The CV2 costs are the sum of the ac-quisition costs, amortization costs, cap-ital costs, trains insurance costs, and the engineers and inspectors costs.There are two columns for each train regarding the energy consumed per km (CVD or CVE), because there are hybrid trains that have different data in those two columns (the rest of the trains will have data in only one of those columns). Hybrid trains, when-ever possible, should work in electric mode. As mentioned in earlier work,1 finding the timings and best routes in a complex dual-gauge railway network Spain, however, has the greatest experience and great-est number of track-gauge changeovers. There are two different train systems1: Talgo and Construcciones y Auxiliar de Ferrocarriles (CAF). Talgo trains3,4 are independent-wheel light trains (with only two wheels situated between every two coaches)either locomotive-hauled or pushed-pulledand many of them incorporate a dual-gauge system. The dual-gauge CAF trains3 are multiple units. The track-gauge changeovers are installed along the French border at the connections on both sides of the Pyrenees and in the country interior (with the latter connecting the high-speed network with the classic network). The first one began operating in commercial service for the Talgo RD (Rodadura Desplazable, or Variable Gauge) BarcelonaGinebra in 1969.4 Talgo trains have been sold, rented, or used in Spain, Portugal, France, Switzerland, Italy, the US, Germany, Argentina, Bosnia-Herzegovina, and Kazakhstan. It seems that a new BerlinMoscow service that takes ad-vantage of Talgos dual-gauge system will be in commercial service soon.5Regarding electrification systems, there were some experiences with three-phase alternating current (AC) in the beginning of the 20th century (in North Italy, Swit-zerland, the US, and a short part of a line in Spain with heavy mining traffic2). Today, four main electrification systems exist: 1.5 or 3 kilovolt (KV) direct current (DC), 15 KV 16 2/3 hertz (Hz) AC (used in Germany, Austria, and Switzerland), and 25 KV 50 Hz AC (the most frequent for high-speed lines).6 Higher voltages require lower intensities and, consequently, a lighter catenary (overhead line) as a thinner conductor cable can be used. In many countries such as France, Spain, Italy, and Belgium, two electrifica-tion systems coexist.Finally, different families of signaling systems exist. In the past, each administration developed its own system, such as the French TVM (Transmission VoieMachine, or TrackTrain Communication), the Spanish ASFA (Anuncio de Seales y Frenado Automtico, or Signal Announcing and Automatic Breaking), and the German LZB (Linienzug-beeinflussung, or Continuous Train Control). Recently, however, the European Train Control System (ETCS)an automatic train protection systemwas designed to replace the existing national systems and improve interop-erability. Its gradual adoption has led to the coexistence of two different signaling systems (if not more) in several European countries.References1. A. Garca-lvarez, Automatic Track Gauge Changeover for Trains in Spain, 4th ed., Fundacin de los Ferrocarriles Espaoles [Spanish Railways Foundation], 2010; www.tecnica-vialibre.es/publicaciones/ficha_tec005.asp.2. J. Arenillas-Melendo, La Traccin en los Ferrocarriles Espaoles [Traction in the Spanish Railways], Via Libre, 2008.3. A. Garca-lvarez et al., Alta Velocidad en Espaa, Lneas y Trenes [High Speed in Spain, Lines and Trains], Va Libre, 2009; www.vialibre-ffe.com/noticias.asp?not=5556&cs=publ.4. M. Galn-Eruste and M. Cano-Lpez-Luzzatti, Talgo 19422012: De un Sueo a la Alta Velocidad [Talgo 19422010: From a Dream to High Speed], Patentes Talgo [Talgo Patents], 2010.5. Gauge-Changing Trains Ordered for MoscowBerlin, Railway Gazette Intl, 22 June 2011; www.railwaygazette.com/news/single-view/view/rzd-and-talgo.html. (no named author)6. List of Current Systems for Electric Rail Traction, Wikipedia.com, 2013; http://en.wikipedia.org/wiki/List_of_current_systems_for_electric_rail_traction#25_kV_AC.2C_60_Hz. (no named author)CISE-15-3-CompSims.indd 91 6/7/13 3:55 PMC o m p u t e r S i m u l a t i o n s92 CoMputing in SCienCe & engineeringeven with double-gauge sections (such as the Spanish one) isnt easy. In this extension, one of the complications consists in the computations related to the hybrid trains, because they have to check (and store) for each section along the chosen route how theyre working (the hybrids can run in electric mode in both the 3 KV DC and 25 KV AC electrification systems, and in diesel model when not in electrified lines).Characteristics of the Independent Costs FileThe new independent costs file fo-cuses on rolling stock, lines, and sta-tions. This file includes eight values (not columns of values):CV 3E1, CV 3E2, CV 3E3, CV 3E4, and CV3E5variable cost 3 (cost per passenger for each k ind of station),CV4variable cost 4 (marketing cost percentage); IVAvalue added tax (VAT); emiDCO2 emissions using diesel traction (CO2 kg/kWh); emiECO2 emissions using elec-tric traction (CO2 kg/kWh);CAcc accident s cost ( Euros/passengerk m);V Tvalue of t ime of travelers (Euros/hour); andOCE other ex ternal cost s of the ra i lway company (Euros/passengerk m).Similar to CV1 costs, CV3 costs are the amounts charged by Adif to Renfe for using the stations (something similar to airport charges). We track each trains energy consumption in the trains file, and then we calculate the CO2 emis-sions for each specific type of train.Our ApproachThe computations performed by the original package RutasOptiRed (best route, time to destination, length of the different sections along the route, and so on) are used by the extension Rutas-OptiRed-II. We denote the travel time for the desired route (in minutes) as min.In Figure 2, two new labels are no-ticeable above the schedule window of RutasOptiRed-IIs screen (this window was already present at RutasOptiRed). One of them, Recorrido ptimo (Optimum Route), would exactly cor-respond to the information provided in the original package. The other la-bel, Costes (Costs), switches the GUI Figure 1. Adifs railway network, November 2012 (courtesy of the Spanish Railway Foundation). The explanation and translation of the legend is as follows: Lneas convencionales (conventional lines); lneas de alta velocidad (high-speed lines).CISE-15-3-CompSims.indd 92 6/7/13 3:55 PMMay/June 2013 93to the new block of information (see Figure 3). We analyze this new block of information in the following section.New Computations (Not Economics-Related)We have several new computations that arent directly related to economics issues. For instance, now the package calculates kmethe mileage using electric trac-tion, in km (the whole mileage if its an electric train or the mileage along elec-trified sectionsthat is, under catenary [overhead lines]if its a hybrid train); kmdthe mileage using diesel trac-tion, in km (the whole mileage if its a diesel train or the mileage along non-electrified sections if its a hy-brid train); kmA1, kmA2, kmB1, and kmC1mileage of the route along type A1, A2, B1, and C1 lines (in km); andPAseats offered per year (see the following formula).PA = passengers per year/average expected utilization percentage =viajPMAIts worth noting here that kme and kmd must be carefully computed in case the train is hybrid, because we must check whether each section along the route is electrified and take that into account.Total CostsThe total cost per seat (CTP) for a certain route and train is given by the formula= + + + + ++ + =CTPcf mrot CV kmCVE kme CVD kmdCV mins CVCV PMAPP CV PMA CGG( 12 ( 3(origin)3(destination))4 ) .i A A B Ci i1, 2, 1, 1The costs per passenger (CTV) and per train (CTT) can be immediately obtained from the CTP by dividing by the average expected utilization percentage (PMA) or multiplying by the number of seats (PLT):CTV =CTPPMACTT = CTP PLT.Figure 2. Calculation with RutasOptiRed-II of the travel time for a series 730 hybrid multiple unit in the MadridA Corua route (6 hours 20 minutes).Figure 3. Economic, energy, and environmental computations associated with the route computed for a series 730 hybrid multiple unit on the MadridA Corua route.CISE-15-3-CompSims.indd 93 6/7/13 3:55 PMC o m p u t e r S i m u l a t i o n s94 CoMputing in SCienCe & engineeringProfitsThe revenue per passenger (IPV) for a certain route using a certain train is IPV = PP 100/(100 + IVA), and the profit per passenger (BPV) is BPV = IPV - CTV. We can easily compute the amounts per seat and per train as we did in the previous section. Energy and EmissionsThe electric energy consumed per train in kWh (EECT), for a certain route, is EECT = kme EEpkm. The diesel energy consumed per train in kWh (EDCT), for a certain route, is EDCT = kmd EDpkm. Therefore, the total CO2 emissions produced per train (emiCO2T) are emiCO2T = EEC emiE + EDC emiD.We can also easily compute these amounts per seat and per train.Other Costs CalculatedThe package calculates several other costs, such as those related to the cost of passengers time, the cost derived from accidents, and other external costs. Because of space constraints, however, we wont go into detail about them.Implementation and ResultsWe implemented RutasOptiRed-II in Visual Basic, as RutasOptiRed. It has been designed to execute under Windows XP or Windows 7, where we extensively tested it. If you run it under Windows XP, NetFramework must be installed before running the package. We tested RutasOptiRed-II with real data f rom Renfes 2012 rol l ing stock and Adifs 2012 net-work (which has more than 700 sec-tions). RutasOpti Red-II returns the results for one train in tenths of a sec-ond, as did RutasOptiRed.To see some of our results, lets re-turn to the functions noted in Figure 3. Figures 4 and 5 show some of the available output.In Figure 4, the different available labels are clearly visible: Distancia recorrida (Distance reroute), Tiempo empleado (Time used), Beneficios y Costes (Profits and Costs), Energa y Emisiones (Energy and Emissions), Coste de Accidentes (Accidents Cost), and Otros Costes Externos (Other External Costs). In Figure 4, the label Distance reroute has been chosen. Meanwhile, in Figure 5, the label Energy and Emissions has been chosen.W e believe that the possibilities of RutasOptiRed have been greatly improved with this exten-sion. Its a specific-purpose package that can be really useful in a complex scenario such as the Spanish railways. We know of no similar tool. In the fu-ture, we plan to use this package with other railway networks. Figure 4. Detail of the window in the lower right side of the screen in Figure 3. Here, the distances computed by the package are detailed: of the 641.7 km of the route, 238.2 were covered using the electric engines fed from the overhead line (catenary) and 403.5 were covered using the diesel engines to feed the electric engines. Moreover, 236.1 km were routed along lines of type A1 and 405.6 along lines of type C1.Figure 5. Detail of the energy consumption computed by the package in the example of Figure 3. Per train, 2,820.29 kilowatts-hour (kWh) of electricity and 12,157.46 kWh of diesel energy are consumed per travel route. The CO2 emissions per train are 32,977.20 kg. Below these figures, the amounts per seat and per passenger are specified.CISE-15-3-CompSims.indd 94 6/7/13 3:55 PMMay/June 2013 95AcknowledgmentsRutasOptiRed was partially funded by the research project Ref. 362-2010 (signed between the Fundacin de los Ferrocarriles Espaoles and the Uni-versidad Complutense de Madrid) and by the research project OptiRed: Desar-rollo del marco regulador del transporte de viajeros por ferrocarril en Espaa (funded by the Spanish government; www.proyecto-optired.es/english/principal.asp). Its extension, RutasOptiRed-II, was partially funded by the research project P116130304 (signed between the Fundacin de los Ferrocarriles Espa-oles and the Universidad Politcnica de Madrid) and by the research project OptiRed: Desarrollo del marco regula-dor del transporte de viajeros por ferro-carril en Espaa.References1. A. Hernando et al., Optimal Route Finding and Rolling-Stock Selection for the Spanish Railways, Computers in Science & Eng., vol. 14, no. 4, 2012, pp. 8289; doi:10.1109/MCSE.2012.80.2. A. Garca-lvarez, Costes Operativos de los Servicios de Transporte de Viajeros por Ferrocarril: Parte I [Operating Costs of Passenger Transport Services by Rail: Part I], Fundacin de los Ferrocarriles Espaoles [Spanish Railways Foundation], 2011.3. A. Garca-lvarez, Relationship between Rail Service Operating Costs and Speed, International Union of Railways (UIC), 2010; www.uic.org/download.php/publication/527E.pdf.4. M.P. Mar t n-Caizares and N. Gonzlez-Franco, Serie 730 de Renfe, el Tren Dual Talgo Todo Terreno [Series 730 of Renfe, Dual Talgo All-Terrain Train], Va Libre, no. 553, 2011, pp. 412; www. vialibre-f fe.com/noticias.asp?not= 7337&cs=mate.5. A. Garca-lvarez, Automatic Track Gauge Changeover for Trains in Spain, 4th ed., Fundacin de los Ferrocarriles Espaoles [Spanish Railways Founda-tion], 2010; www.tecnica-vialibre.es/english/publications/file_tec005.asp.6. Adif, D.E. Circulacon. Tomos I & II [Executive Board of Traffic. Volumes I & II], CIRculaciones por TRAmos (CIRTRA) 2009 [Circulations by Sections], ann. report, Adif, 2010.7. N. Adler, E. Pels, and C. Nash, High-Speed Rail and Air Transport Competi-tion: Game Engineering as a Tool for Cost-Benefit Analysis, Transportation Research Part B, vol. 44, no. 7, 2009, pp. 812833; doi:10.1016/j.trb.2010.01.001.8. G. de Rus, J. Campos, and G. Nombela, Economa del Transporte [Transport Economics], Antoni Bosch, ed., Rustica, 2003; www.antonibosch.com/libro/economia-del-transporte. 9. O. Fridh, Perspectives for a Future High-Speed Train in the Swedish Domestic Travel Market, J. Trans-port Geography, vol. 16, no. 4, 2008, pp. 268277; doi:10.1016/j.jtrangeo. 2007.09.005.10. K. Kottenhoff, Evaluation of Passen-ger Train Concepts: Practical Methods for Measuring Travellers Preferences in Relation to Costs, Proc. 3rd KFB Research Conf., KTH (The Royal Inst. of Technology); www.transguide.org/KFB/3rd_KFB_research_conference/Kottenhoff.pdf.11. P. Vignes and L. Debosque, La Main-tenance du TGV SE: Exprience de Huit Annes dExploitation [Mainte-nance TGV SE: Eight Years of Experi-ence Operating], Revue Gnrale des Chemins de Fer (RGCF) [General Rev. of Railways], vol. 108, nos. 78, 1989, pp. 3350.Eugenio Roanes-Lozano is currently an associate professor in the Algebra Depart-ment at the Universidad Complutense de Madrid, Spain. His research interests include the applications of computer algebra to arti-ficial intelligence (AI), transportation engi-neering, and education. Roanes-Lozano has a PhD in mathematics from Seville University and a PhD in computer science from the Polytechnic University of Madrid. Contact him at eroanes@mat.ucm.es.Antonio Hernando is currently a lecturer in the Intelligent Applied Systems Depart-ment at the Poly technic Univers i t y of Madrid. His research interests include AI and modeling. Hernando has a PhD in computer science from the Polytechnic University of Madrid. Contact him at ahernando@eui. upm.es.Alberto Garca-lvarez is currently the Ex-ecutive Director of Passengers for Renfe. His research interests include energy consump-tion and railway operations. Garca-lvarez has a PhD in transport infrastructures and engineering from the Polytechnic University of Catalunya. Contact him at albertoga@ renfe.es.Luis Eduardo Mesa is currently a researcher in the direction of research, training, and sci-entific collaboration at the Spanish Railways Foundation. His research interests include energy consumption and railway operations. Mesa has an MS in geography from the Complutense University of Madrid. Contact him at observatoriodelferrocarril@ffe.es.Ignacio Gonzlez-Franco is currently a researcher in the direction of research, training, and scientific collaboration at the Spanish Railways Foundation. His research interests include energy consumption and railway operations. Gonzlez-Franco has an MS in industrial engineering from Vigo Uni-versity. Contact him at igonzalez@ffe.es.Selected articles and columns from IEEE Computer Society publica-tions are also available for free at http://ComputingNow.computer.org.CISE-15-3-CompSims.indd 95 6/7/13 3:55 PM

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