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on which equipment fails and the train routes related to the failed equipment.
Several examples are described in section 4.1.3. Since it will be dicult to es-
timate the movement only by a desk study, we use the train trac simulator
to perform detailed estimation. This simulator is based on the programme
which was developed for evaluating a signalling regarding a minimum head-
way, recovery performance from delay and so on. The original programme
simulates movements of trains in reflection of train control and interlocking
function. In the new simulator, a downtime and impact on a route control
(e.g., all trains should stop, train runs through alternative route) can be set
for each equipment. The number of trains which can be operated during the
failure is obtained from the simulation.
In the next step, the expected loss is derived by a product of the loss of
fare revenue obtained in the first step and the failure rate of each equipment.
The failure rate corresponds to an indicator of reliability.
The expected loss of the whole system is obtained by summing the ex-
pected loss for each equipment. The resulting loss reflects factors of main-
tainability and reliability, and expresses the risk level of a train operation
service. Therefore, it is a kind of availability indicator.
4
Case Study of Applying the Method
4.1
Preconditions
Model of Line and Station We assume three types of model stations, as
indicated in Fig.3 and Table 1. Station A and Station B are common models
of high density lines, and Station C is a model of suburban lines.
Fig. 3. Models of Stations
Model of Signalling System We have assumed three types of signalling
systems for the case study. The model systems are outlined in Fig.4. The first
one is a conventional system consisting of track circuits, wayside signals, etc.
The second is a train control system based on radio communications, similar
to CARAT [1] or ATACS [2] in Japan.
The third one is a future system based on a new concept. We performed
basic experiment on the new system and have confirmed its feasibility. The
system is outlined in Fig.5 and has the following features.
