Railway Infrastructure Robustness : Attributes, evaluation, assurance and improvement

Abstract: According to the European program Horizon 2020, multifaceted challenges in transportinfrastructure include 1) making infrastructure more resilient to keep pace with the increasing mobility needs; 2) reducing the impact of infrastructure on the environment;and 3) dealing with declining resources to maintain and upgrade transport infrastructure. New design and maintenance approaches must be developed to handle these issues, ascurrent methods are inadequate.In maintenance practices of railway infrastructure, most attention has been placed on RAMS (Reliability, Availability, Maintainability and Safety) study to meet asset safety and availability requirements. In Sweden, a popular development of the concept is RAM4S which incorporates supportability, sustainability, and security. However, the reality is more complex than these concepts suggest; various natural or operational uncertaintiescan cause “unfavourable” conditions requiring a quite different approach.Resilience studies can improve the ability of an infrastructure to withstand disturbances caused by uncertainties. To this point, most studies have considered extreme events,including natural events, like earthquakes or floods, and man-made events, like deliberateattacks on infrastructures. However, both naturally caused and operationally caused unfavourable conditions which do not belong to extreme events need to be studied as well. This represents a significant gap in the research.Robustness as a part of resilience has attracted much attention in recent years as it may be able to sufficiently consider those unfavourable conditions. In railway systems, however, robustness studies have mainly been aimed at timetable management to handle delays (including secondary delays) within the system. Yet according to statistics on total delays for the year 2015, from the follow-up system of the Swedish Transport administration (Trafikverket), LUPP, more than 30% of the root causes of delays are due to non-robustinfrastructures.To fill the above research gaps and support decision making of a railway infrastructure manager, the study described in the thesis conducts a holistic examination of railway infrastructure robustness considering its attributes, evaluation, assurance and improvement by investigating, exploring and developing new definitions and approaches. First, it develops a new road map for railway infrastructure robustness, including a novel definition and a framework. Its overview of robustness related topics results in a unique definition that identifies attributes of railway infrastructure robustness and clarifies the research boundaries between robustness and reliability, resilience, and risk. The study’s ground-breaking framework, named house of robustness management (HORM), is based on continuous improvement to support infrastructure robustness management in railway;HORM consists of robustness management goals and guidance, a continuous improvement process, and support systems through which assurance and improvement can be supported. Second, in addition to the qualitative evaluation of railway infrastructure robustness enabled by the road map, the study proposes a new quantitative evaluation approach by considering a dataset of “specified disturbance”, a corresponding “acceptable functionality”, and a dataset of weights of risk preference. Third, to apply railway infrastructure robustness to the development of sustainability, it provides a case study on energy efficiency optimisation in Sweden.This thesis consists of two parts. The first gives an introductory summary of the subjectand research, followed by a discussion of the appended papers, suggested extension of the research and conclusions. The second part consists of three appended papers. The first paper concerns the new road map including the definition and a framework. The second paper proposes a new quantitative evaluation approach for railway infrastructure robustness. The third paper is a case study on railway switches & crossings which will be further pursued under the topic of “green robustness”. The three subsequent papers develop the dependability improvement of railway infrastructure considering information logistics and risks, as well as maintenance cost.