Safety-based maintenance for geometry restoration of railway turnout systems in various operational environments

Turnout system is one of the most critical infrastructures in the railway operations. As high demand in railway operation, the railway operators have to increase the axle load, traffic density and speed of the operation. These would be able to give high impact to the turnout system as increasing the vibration level and noise when the rolling stock crossing the turnout. Therefore, any failure in turnout system can cause negative impact to the operation in scope of maintenance cost and catastrophic consequence effect from the failure could happen such as major derailment. Safety-based maintenance (SBM) approach is an effective maintenance that takes safety into account in the maintenance by analysing the probability of the failure occurrence and severity of the consequence. Safety analysis is to ensure that the probabilities of the failure occurrence and the consequence from the failure such as death or injury and damage or loss of property can be minimised as to a level that is as low as reasonably practicable (ALARP). In this study, SBM and ALARP will be used to demonstrate the optimisation of geometry restoration activities of the railway turnout, which is essential for the safety requirements and quality standards. The failure behaviour in different operational environment such as effect of temperature, humidity, snow, dust, corrosive environment and natural calamity will be analysed to form fault tree analysis and establish a safety-based maintenance approach that is practical and useful for railway industry.