Selection of operational criteria for a collision avoidance system

Abstract

In fallback situations as well as in construction sites collisions between rail vehicles are one of the major common accident causes. Common interlocking and train control systems support undisturbed operation. The GALILEO programme is Europe’s initiative to develop a civil global navigation satellite system that provides highly accurate and reliable positioning, navigation and timing services. GALILEO will provide real-time positioning services at the metre level as a result of improved orbits, better clocks, dual frequency and enhanced navigation algorithms as well as integrity information. For safety of life (SoL) applications, local elements can be integrated to provide more accurate positioning, communication and/or information services. For example, GALILEO Local Elements will be developed and adapted to meet specific requirements in rail transportation. This allows also for a modernization of automatic train control technology. This is advisable because of the still existing collisions between trains or other kinds of obstacles (construction vehicles, construction workers, pedestrians), even if comprehensive and complex technology is extensively deployed in the infrastructure which should help to avoid such collisions. Experiences from the aeronautical Traffic Alert and Collision Avoidance System (TCAS) as well as the maritime Automatic Identification System (AIS) have shown that the probability of collisions can be significantly reduced with collision avoidance support systems, which do hardly require infrastructure components. In this article an approach is proposed for a “Railway Collision Avoidance System - RCAS” consisting only of mobile ad-hoc components, i.e. without the necessity of extensions of the railway infrastructure. Each train determines its position, direction and speed using GALILEO and broadcasts this information via mobile radio, complemented with other important information such as dangerous goods classifications in the region of its current location. This information can be received and evaluated by other trains, which may – if a potential collision is detected – lead to traffic alerts and resolution advisories up to direct interventions, which is usually applying the brakes. The contribution presents a selection of the relevant scenarios for the application of RCAS. Low Traffic density lines are well suited as well as large construction sites and industrial networks. Specific application cases are shunting yards, where a very high number of moving objects are supervised.