RAMS and LCC in rail track maintenance

Abstract: Railway infrastructure is a complex system. An important aspect of the rail infrastructure is that the assets have a long useful life. So once installed, it is very difficult to modify the initial design. Thus, the performance of the infrastructure depends on the maintenance and renewal decisions taken during its life cycle. In many countries, restructuring railways and increasing efficiency requirements cause a changing environment for infrastructure management. Responsibilities for parts of the railway system are often handed over to different players. In order to guarantee optimal long-term results for the railway systems, the effects of decision should be systematically evaluated. The infrastructure manager, responsible for design, construction, maintenance, renewal and upgrading the infrastructure, has a clearly defined role and is confronted by increasing performance of the associated partners. Due to increase in operation and maintenance costs, infrastructure managers are compelled to optimise budget, while reliability and availability have to be increased without endangering the traffic safety. A systematic approach is needed by the infrastructure manager for guaranteeing defined levels of performance. As in the current scenario, most of the maintenance and renewal decisions are based on past experience and expert estimations, a need for Life cycle cost (LCC) approach arises. A life cycle costing approach considering Reliability, Availability, Maintainability & Safety (RAMS) analysis will provide a way to optimise the maintenance strategy, considering the short term budget requirements as well as long term costs of ownership. To achieve overall RAMS and LCC objectives of the system, it is important to follow systematic RAMS/ LCC actions through out the life cycle of the system. One of the important phases of the track system life cycle is the operation and maintenance phase due to its long phase life where RAMS and LCC are to be optimised. The aim of this thesis is to develop an approach for making effective maintenance decisions based on RAMS and LCC analysis. The thesis looks into three aspects of RAMS and LCC analysis, i.e. defining RAMS and LCC in track maintenance context, applicability of RAMS and LCC in maintenance planning of track and uncertainty associated with LCC due to RAMS parameters. The thesis provides an approach for an effective RAMS and LCC analysis during operation and maintenance phase. The thesis also comprises of the state-of-the-art of RAMS and LCC analysis followed by infrastructure managers and railway manufacturers in Europe. This work has been done as a part of a European project. To realise the benefits of large investments on railway infrastructure, effective maintenance is required. An approach has been developed on how RAMS and LCC facilitates in taking effective maintenance decisions. An integrated maintenance management system along with RAMS management system and LCC management system is must for arriving at the correct decisions. The LCC modelling followed by Banverket (Swedish National Rail Administration) for re-investment and upgrading projects have been described. While taking decisions of maintenance on the track based and RAMS and LCC, uncertainty associated with LCC should be considered. The research presents the uncertainty associated with LCC estimation and defines an approach to calculate uncertainty in LCC estimation due to RAMS parameters. A case was study carried out on iron ore line (Malmbanan) that runs from Luleå to Narvik. The RAMS data were collected from different Banverket's databases. The study helps in calculating uncertainty associated with LCC and thereby act as a decision support tool for effective track maintenance.