To detect trains, track circuits are generally used in railway signaling systems, which sometimes malfunction due to the rust of rails or for other reason's. Moreover, there are some problems in the maintenance of track circuits. Therefore, a train detection device using microwave balises has been developed. It features non-contact with the rail and capability of tracking train detection. This device has greatly improved functions of train detection and tracing, because trains equipped with ID-balises and the device individually detect trains by using the ID-balises in contrast to the existing track circuits that detect only the "existence (0)" or "non-existence (1)" of a train. Therefore, the function of this device makes the composition of train control system simpler and improves the safety of train operation. Moreover, the train control system can be constructed at low costs because logical devices are not needed for the car-borne equipment.

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We present a new safety analysis method for railway signaling systems and introduce component fault occurrence probability vector, functional failure probability vector, correlation matrix between functional failures and component faults, mitigating matrix, and several other factors. By using these factors, we can estimate the risk of signalling systems, the effectiveness of safety measures, dangerous system failure probability and other related values. We also introduce a new automatic train control system and safety technologies, and evaluate the effectiveness of these technologies by calculating the elements of mitigating matrix.

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To improve the quality of software, formal methods are expected to be proper solutions. They enable rigorous analysis of systems specifications. In this report, we introduce formal methods into the specification of digital ATC track database. This specification defines the invariants to be kept at all times and a small set of operations. Proof obligations, which are items to be proved in order to verify the integrity of the specification, are then generated automatically. All of the proof obligations are mechanically proved to the fullest, although some proof obligations are proved interactively.

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Most railway companies protect track maintenance workers wholly relying on human attention to post train watchers, use safety manuals and implement safety guidance. It is reported that injuries and train accidents related to maintenance work are mostly caused by human errors. To support measures to prevent such injuries, therefore, we have developed a system to continuously provide track maintenance workers with information on the latest status of train operation in CTC sections.

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In recent years, radio telecommunications have become increasingly important for railway systems. We have studied methods for the calculation of radio propagation characteristics along railway lines, and proposed a new calculation method based on that of ORE A 133. We have also confirmed that the proposed method can calculate the radio signal strength along railway lines at sufficiently high precision in comparison with the conventional method. Furthermore, we have developed a radio propagation characteristics calculation program for easy application of the new method.

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In recent years, Digital Subscriber Line (xDSL) technology is attracting attention as a high bit rate data transmission technology using existing metallic cables. In this paper, we discuss the introduction of xDSL technology into railways as a data transmission method by metallic cables. First, we describe an outline of the metallic cable transmission systems in railway operation. Second, we list the subjects to be discussed for introducing the xDSL technology into railways, and report performance and field tests of xDSL transceivers. In these tests, we were able to prospect the xDSL technology and obtain part of basic data for introduction into railways.

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In the field of international standards such as IEC standards, safety is generally explained with risk. In the risk analysis process, it is a very important task to calculate the reliability of large-scale systems which include equipment and operators. As for the railway risk analysis, there are many cases that conventional techniques, such as event trees (ETs), and fault trees (FTs), which are broadly used as practical tools, can not be applied adequately. This is because, for the railway system, there are a number of subsystems with complicated dependencies. Then, we developed a new network-type reliability evaluation model, Typed State Influence Diagram (TSID), which can explicitly express such a complicated dependency.

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The Signalling and Telecommunications Technology Division (hereinafter referred to as "STTD") is now promoting research and development on low-cost and high-performance signalling systems and application of general-purpose telecommunications technology to railways. This special edition on signalling and telecommunications technology highlights the computer and microwave balise aided train control system (COMBAT) that uses radio for train detection and several other research results. This report introduces other systems that have been developed in recent years, but not included in this edition.

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