Performance Investigation on AA-LRT Automatic Train Protection System
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Date
2019-06-07
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Addis Ababa University
Abstract
Railway signalling system consists of the system, the device and means by which trains are operated safely and efficiently. Signalling enables the movement of trains to be controlled in such a way that the existing tracks are utilized to the maximum while maintaining the safety of passenger, rolling stock and the staffs. As part of signalling automatic train control system, the Automatic Train Protection (ATP) is applied to assure the safety of train movement by preventing collisions and derailments.
In this paper a feared event model (ATP not available) of the Addis Ababa Light Rail Transit (AA-LRT) signal Automatic Train Protection system (which is an intermittent type) is developed from system composition and configuration using a Fault tree. The in-depth analyses of the Reliability, Availability, Maintainability and Safety (RAMS) of the AA-LRT signal intermittent-Automatic Train Protection (iATP) system is performed using the signalling system detailed design data and maintenance data. The signal iATP system is composed of different subsystems in series like the Line-side Electronic Unit (LEU), Beacon (B), Trackside Radio Equipment (TRE), Carborne Controller (CC), Driver Machine Interface (DMI), Beacon Antenna (BA), Onboard Antenna (OA) and Odometer (OM).
Mathematical model of the signal iATP subsystems have been developed using Markov process. The selected study methodologies which are quantitative and analytical data analysis methods are evaluated and graph is plotted for different time intervals. Hence the reliability and maintainability of every subsystems are evaluated with graph to investigate their performance at different time intervals.
The analysis from this thesis shows that the reliability of the LEU, Beacon (B), TRE, CC, DMI, BA, OA and OM are 0.9753, 0.9975, 0.9048, 0.9512, 0.9875, 0.9631, 0.9559 and 0.9875 respectively after 2500 hours of operation, the reliability of the entire signal iATP system after 2500 hours of operation is 75.16 % and the maintainability of the LEU, Beacon (B), TRE, CC, DMI, BA, OA and OM after one hour are 0.9092, 0.8997, 0.8646, 0.9257, 0.9391, 0.8891, 0.8775 and 0.8891 respectively according to the design and maintenance data.
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Keywords
intermittent-Automatic Train Protection, Reliability, Availability, Maintainability, Safety, Fault tree, Markov process