Search

Broken rails are the most frequent cause of freight-train derailments in the United States. Consequently, reducing their occurrence is a high priority for the rail industry and the U.S. Federal Railroad Administration. Current practice is to periodically inspect rails to detect defects using nondestructive technology such as ultrasonic inspection. Determining the optimal rail inspection frequency is critical to efficient use of infrastructure management resources and maximizing the beneficial impact on safety. Minimization of derailment risk, costs of inspection vehicle operation, rail defect repair, and corresponding train delay are all affected by rail inspection frequency. However, no prior research has incorporated all of these factors into a single integrated framework. The objective of this paper is to develop an analytical model to address the trade-offs among various factors related to rail defect inspection frequency, so as to maximize railroad safety and efficiency. The analysis shows that the optimal inspection frequency will vary with traffic density, rail age, inspection technology reliability, and other factors. The optimization model provides a tool that can be used to aid development of better-informed, more effective infrastructure management and accident prevention policies and practices. [ABSTRACT FROM AUTHOR]

Railways around the world are experiencing growth in traffic demand and the need to expand their network and line capacity. To accommodate the substantial demand, the conventional railway operator in Taiwan, the Taiwan Railways Administration (TRA), is interested in understanding the potential benefit of adopting various advanced signaling systems, such as hybrid or moving-block systems. In this study, the authors developed a set of analytical capacity models for conventional rail operations with advanced signaling systems, which were implemented in the busiest corridor in the TRA system. The empirical results show that advanced signaling systems generally have positive capacity effects. However, the benefit may not be substantial due to constraints from the station track layouts. Therefore, possible capacity improvement alternatives, such as improving track layouts and upgrading signaling systems, should be considered together to determine the optimal capacity improvement plan. The use of these proposed capacity models can help railway agencies with similar operational environments in their capacity management and resource planning projects. [ABSTRACT FROM AUTHOR]

This special issue is based on a selection of the four best papers from the Third International Seminar on Railway Operations Modelling and Analysis held in Zurich from 11 to 13 February 2009. The papers have been selected and reviewed by Board and other senior members of the International Association of Railway Operations Research (IAROR) and subsequently revised by their authors. The authors and their papers come from universities in Sweden, The Netherlands, Italy, Switzerland and Portugal. They represent valuable contributions to the current state of scientific and professional knowledge in the area of railway operations that can stimulate the broader application and further development of advanced analytical, combinatorial and simulation models. [ABSTRACT FROM AUTHOR]