Railway Track Inspection and Maintenance Scheduling For Addis Ababa Light Rail Transit
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Date
2016-08
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Addis Ababa University
Abstract
Ethiopia has recently finished constructing the first Light Rail Transit (LRT), in the history of the country. Our new experience demands other pioneer countries’ huge experience on LRT track inspection methods, frequency and maintenance tolerance limits. In this study, different track safety standards, maintenance standards and best practices from the railroad industry are surveyed to keep the Addis Ababa LRT track performance satisfactory.
Rail failures generally occur from fatigue cracks that form and grow in the rail steel as a result of cyclic forces caused by the repeated passage of train over the rails which may cause a train to derail. There are many sources that influence Track defects and failure. These effects include bending and shear stresses, wheel/rail contact stresses, thermal stresses, residual stresses and dynamic effects
This study on scheduling inspection of railway track first addresses defects which affect the safe running of the railway. A list of the common defects which may be found whilst inspecting the permanent way are included. After defects are identified, prioritization are made based on their relative perceived urgency. To do that, inspection parameters are discussed with their tolerance limits compared in different railway manuals and standards. Then the unique features of AA LRT are described, such as its track specs, technical and rolling stock parameters. The effect of those unique features on track inspection are also explained. Finally, an optimum frequency of track inspection is provided for the Addis Ababa LRT considering the design and operational parameters of our new light rail and comparing it with other railway standards.
It was found that, different railway agencies has different track maintenance tolerance limits and frequencies of inspection based on factors like track class, track material properties, service defect rate, defect experience and defect growth rate. But in the case of AA LRT, since it is a new railway line, defect experience and defect growth rate are not considered to calculate optimum frequency of inspection. Accordingly, fixed schedule are provided based on the most commonly used standards.
Current track inspection methods, techniques and best practices in the railroad industry are covered in detail, including visual inspections, several automated and remote inspection options, so that the best inspection technology that suits the Addis Ababa LRT can be chosen to maintain a safe railway network. The cheapest and most efficient way is to catch problems before they get too large, and repair them before they cause a derailment. Inspection methods are chosen considering cost, efficiency, and availability with the specific conditions of the Addis Ababa LRT.
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Keywords
Railway Inspection, Inspection parameters, Inspection Frequency, Maintenance Priority, Track Defects, Tolerance limits