4 research outputs found

    Probabilistic Safety Analysis of High Speed and Conventional Lines Using Bayesian Networks

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    [EN] A Bayesian network approach is presented for probabilistic safety analysis (PSA) of railway lines. The idea consists of identifying and reproducing all the elements that the train encounters when circulating along a railway line, such as light and speed limit signals, tunnel or viaduct entries or exits, cuttings and embankments, acoustic sounds received in the cabin, curves, switches, etc. In addition, since the human error is very relevant for safety evaluation, the automatic train protection (ATP) systems and the driver behavior and its time evolution are modelled and taken into account to determine the probabilities of human errors. The nodes of the Bayesian network, their links and the associated probability tables are automatically constructed based on the line data that need to be carefully given. The conditional probability tables are reproduced by closed formulas, which facilitate the modelling and the sensitivity analysis. A sorted list of the most dangerous elements in the line is obtained, which permits making decisions about the line safety and programming maintenance operations in order to optimize them and reduce the maintenance costs substantially. The proposed methodology is illustrated by its application to several cases that include real lines such as the Palencia-Santander and the Dublin-Belfast lines.Grande Andrade, Z.; Castillo Ron, E.; Nogal, M.; O'connor, A. (2016). Probabilistic Safety Analysis of High Speed and Conventional Lines Using Bayesian Networks. En XII Congreso de ingeniería del transporte. 7, 8 y 9 de Junio, Valencia (España). Editorial Universitat Politècnica de València. 362-371. https://doi.org/10.4995/CIT2016.2015.3428OCS36237

    Review of the planning and distribution methodologies to locate hydrogen infrastructure in the territory

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    The member countries of the European Union (EU) have prioritized the incorporation of hydrogen as a key component of their energy objectives. As the world moves towards reducing its dependence on fossil fuels, alternative sources of energy have gained prominence. With the growing development of Fuel Cell Electric Vehicles (FCEVs), the establishment of an infrastructure for hydrogen production and the creation of a network of service stations have become essential. This article’s purpose is to conduct a methodical review of literature regarding the use of green hydrogen for transportation and the planning of imperative infrastructure in the territory of the EU, specifically Hydrogen Refueling Stations (HRS). In order to increase the acceptance of fuel cell vehicles, a comprehensive network of hydrogen refueling stations (HRS) must be built that enable drivers to refuel their vehicles quickly and easily, similar to gasoline or diesel vehicles. The literature review on this topic was conducted using the Web of Science database (WOS), with a variety of search terms proposed to cover all the key components of green hydrogen production and refueling infrastructure. The implementation of HRS powered by renewable energy sources is an important step in the adoption of fuel cell vehicles, and overcoming the obstacles that come with their implementation will require cooperation and innovation from governments, private businesses, and other stakeholders.Peer ReviewedPostprint (published version

    Alternate Double Single Track Lines

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    [EN] The paper discusses the advantages and shortcomings of alternate double single track (ADST) lines with respect to double track lines for high speed lines. ADST lines consists of sequences of double and single track segments optimally selected in order to reduce the construction and maintenance costs of railway lines and to optimize the timetables used to satisfy a given demand. The single tracks are selected to coincide with expensive segments (tunnels and viaducts) and the double tracks are chosen to coincide with flat areas and only where they are necessary. At the same time, departure times are adjusted for trains to cross at the cheap double track segments. This alternative can be used for new lines and also for existing conventional lines where some new tracks are to be constructed to reduce travel time (increase speed). The ADST proposal is illustrated with some examples of both types (new lines and where conventional lines exist), including the Palencia-Santander, the Santiago-Valparaíso-Viña del Mar and the Dublin-Belfast lines, where very important reductions (90 %) are obtained, especially where a railway infrastructure already exist.Moraga Contreras, P.; Grande Andrade, Z.; Castillo Ron, E. (2016). Alternate Double Single Track Lines. En XII Congreso de ingeniería del transporte. 7, 8 y 9 de Junio, Valencia (España). Editorial Universitat Politècnica de València. 527-536. https://doi.org/10.4995/CIT2016.2015.3426OCS52753

    Probabilistic safety analysis of railway lines

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    A new probabilistic safety assessment method applicable to conventional and high speed railway lines is presented. The main idea consists of reproducing the railway line items which are relevant to safety by means of a Bayesian network as an alternative to more limited event and fault tree structures. The model evaluates the probability of incidents associated with the circulation of trains along the lines with special consideration of human errors. To this end, all the line relevant elements, such as light and speed limit signals, rolling stock failures, falling materials, slope slides in cuttings and embankments, tunnel or viaduct entries or exits, automatic train protection systems and other elements are reproduced with a special consideration of human behavior and human error. Since driver’s attention plays a crucial role, its evolution and changes with driving time and due to other factors, such as seeing light signals or receiving acoustic signals are taken into account. The model updates the driver attention level and evaluates the probability of accident associated with the different elements encountered along the line. A continuously increasing risk graph with continuous and sudden changes is obtained indicating where actions must be taken to improve safety. This avoids waste of time and money by concentrating on the items most critical to safety. Finally, some illustrative examples are used to point out the models relevance.Depto. de Estadística y Ciencia de los DatosFac. de Estudios EstadísticosTRUEpu
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