# Analysis, Evaluation and Simulation of Railway
## 1 Introduction  
Different policies for improving Energy Efficiency (EE) are a cumber stone for sustainability objectives both for the European Union (EU) and for other countries worldwide. Transportation explains a high percent of the final use of energy, and should have considerable potential for improvement. For this reason, in last decade sustainability is also an important issue for the main associations of the railway sector, such as the International Union of Railways (UIC) and the Community of European Railway and Infrastructure Companies (CER) [1; 2]. For these associations, and taking 1990 consumption baseline, the objectives are: Fifty percent reduction in the intensity of energy use (energy per passenger and km, i.e., kWh/pkm, or energy per ton and km, i.e., kWh/tkm) in 2030 (0.09 kWh /pkm), and sixty percent in 2050. In terms of environmental objectives, a reduction in emissions of 75% in 2050 is foreseen. To limit the expansion and dominance of road-based transportation, and to increase the market share of the so-called eco-friendly transport modes (railways and maritime transport), different countries are working in different working areas: For instance, Poland through a model of national intermodal transport [3], or the One Belt One Road Initiative (OBOR) of China, and,especially, the OBOR container freight trains operating since 2011 between Europe and China. Around 13,000 trains have been operated in the last eight years [4]. Railway transportation has several advantages that explain its development in the last decade both in the passenger sector (for instance, the development of 25,000 km of high-speed infrastructures in China [5]), but mainly in the freight sector: Short time (one-third of shipping), no weather influence, high safety, green environmental protection, and its complementarity with shipping transportation (and the development of new harbor infrastructures around the world [5]). An important remark for railways is that passenger transport is cost-effective in some countries, but only for high-speed services (for example in Spain). Freight transport produces profits and predominates in some countries (Canada and the USA), or is operated with high capacity factors (up to 90% in the North Rail Express Freight service, in the north of Europe), in the case of Deutsche Bahn (DB) in Germany (the largest market for freight). For instance, the freight operator DB Cargo will raise its rail traffic volumes in Germany by 70% by 2038-2050 [6]). But it is also known that conventional passenger and freight services very much rely, on a great deal, upon of subsidies from their governments (e.g., China Railway Express [5]). This can be improved through better use of energy (an important cost for the operation of railways) with energy management systems that look for optimal management in railway system, while integrating all energy resources of the system [7,8]. The objectives of different associations and operators in the medium and long term involve the integration of technologies and procedures that have the potential to reduce the impact of the transportation sector on the overall energy demand. Especially, improvements in the following items are considered by international associations (e.g., UIC) and railway operators (e.g., DB), but also by authors in this work:  
_Improvements of efficiency in locomotives with internal combustion engines (ICE):_ Diesel-electric haulage is a well-known technology, but this alternative has a considerable uncertainty in the future because electric traction has a considerable superiority (more power, efficiency, or lower maintenance costs). Nowadays, diesel locomotives still are in excess in some countries and are used more and more at a minimum level. Nevertheless, they are necessary because railway systems usually have a significant percentage of non-electrified routes. The idea is optimizing efficiency, through storage and regenerative braking, and, besides, to study the possibilities of static and dynamic storage and generation.