The large tonnage mines use railway transportation as a system for mineral transportation. The rolling stock health condition study and improvement not only reduce the lifecycle cost of the assets but also ensures safe, reliable, punctual, and efficient transportation. The remaining useful life estimation is an efficient approach to condition-based maintenance, prognostics, and health management. This paper aims to predict the remaining life of a mining rolling stocks in the presence of operational environmental effects. In this study, the operation and failure data were obtained from Malmbana, LKAB, Sweden, a Swedish Railway Company, considering the effective operational factors. The failure behaviour of the railcar was evaluated and then the proportional hazard model was used to estimate the conditional reliability functions and accordingly the remaining useful life at the various initial survival time. Finally, the reliability-based time interval is applied to plan the maintenance operations. Results of this study show that the operator’s skill level and the maintenance quality had a significant influence on the reliability performance. By considering the proposed PM plan according to the desired reliability level, the remaining lifetime of the rolling stock will be improved by 78.10%, on average.