Friction is the bond linking the tangential and normal forces at the wheel-rail interface. Modeling friction is the precondition for the wheel-rail adhesion calculation. In this work, the critical role of friction in the calculation of wheel-rail adhesion is discussed. Four types of friction models (Coulomb model, linear model + Coulomb model, rational model and exponential model) which are commonly used for the calculation of wheel-rail adhesion are reviewed, in particular with regard to their structural characteristics and application state. The adhesion coefficients calculated from these four friction models using the Polach model are analyzed by comparison with the measured values. The rational model and the exponential model are more flexible for defining the falling friction, and the adhesion coefficient calculated by these two models is highly consistent with the measured one. Though the rational model and exponential model describe the falling friction well, the existing friction models are not applicable for calculating adhesion after considering more realistic factors, such as thermal effect, contaminants and so on. Developing a novel and practical friction model to accurately describe the wheel-rail friction behavior is still an essential but challenging and significant task. This review provides a reference for the selection of existing friction models and generates fresh insights into developing novel and practical friction models.

The objective of this paper is to look at the problem of high-speed rail (HSR) passengers’ luggage and provide alternative solutions to improve luggage handling. A qualitative study is carried out to assess the current state of HSR practices, analyse existing issues with HSR passenger luggage and provide alternative solutions, including modification of the passenger unit, double-deck rolling stock, an additional train for transporting luggage, and repositioning of passenger seats. Four solutions are discussed that could solve the problem of HSR passenger luggage handling and evaluated from  four aspects namely passengers, railway operator, cost and passenger comfort level. The solution of additional trains for transporting luggage may be the preferred solution when compared with other options, without compromising the comfort of the passengers or the profit of the railway company.

The global COVID-19 pandemic is having a significant impact on the development of many aspects all over the world. As an important part of public services, rail transit requires effective response countermeasures to control the spread of COVID-19. Considering the current development of the epidemic situation, this article discusses the characteristics of COVID-19 transmission and identifies vulnerable areas to target in order to prevent and control the spread of the epidemic in the rail transit system. Countermeasures adopted to prevent the spread of COVID-19 are analyzed in terms of external and internal categories, which were classified into six groups: passenger service, case care, information, staff, equipment and operation management. An evaluation architecture was also constructed, which was established from the perspective of effectiveness, economic efficiency, acceptability, privacy and so on. The effect of implementing the measures was evaluated by a social survey, and their advantages and shortcomings were analyzed, which can be used to guide future epidemic prevention and control for rail transit systems around the world. It is important to formulate a reasonable work schedule according to local conditions, providing a reference for rapid response to future public health emergencies of international concern.

Failures of third rail insulators, which often impose problems that affect the serviceability of transit systems, rarely have been investigated. This study examines various aspects of third rail systems, identifies causes of insulator failures, and develops and categorizes preventive strategies. To accomplish the goals, the existing literature was reviewed and analyzed to identify various characteristics of third rails and insulators. Then, five transit case studies were analyzed to determine the characteristics of third rails, identify the causes of insulator failures, and evaluate the preventive strategies adopted by transit agencies. The results revealed that local environmental conditions cause degradation of insulators, with dirt build-up being the biggest contributor to failure. Performing maintenance and inspections of insulators at predetermined intervals was also shown to be very effective for preventing failure. The preventive strategies were classified into three categories: regular inspections; preventive maintenance programs; and regulation and safety, with regular inspections being the most frequently adopted. Findings of this study will serve as an appropriate source of information for practitioners who work with third rail systems and will help them adopt effective strategies.