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

[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

A computer-aided model for the simulation of railway ballast by random sequential adsorption process

This paper presents a computer-aided multi-stage methodology for the simulation of railway ballasts using the Random Sequential Adsorption (RSA – 2D domain) paradigm. The primary stage in this endeavour is the numerical generation of a synthetic sample by a "particle sizing and positioning" process followed by a "compaction" process. The synthetic samples of ballast are then visualised in the Computer-Aided Design (CAD) environment. The outcomes of the simulation are analysed by comparison with the results of an experimental investigation carried out using a methacrylate container in which real samples of railway ballast are formed. A test of model reliability is carried out between the aggregates number and the grading curves of the synthetic sample and the real one. A validation is therefore performed using the ground-penetrating radar (GPR) non-destructive testing (NDT) method and the finite-difference time-domain (FDTD) simulation developed in a computer-aided environment. The results prove the viability and the applicability of the proposed modelling for the assessment of railway ballast conditions