Scalable and relocatable interlocking device

Author: Natsuki Terada
Day: Aspect Day Two
Session: Architecture

Most of interlocking devices are installed at stations. When a
trouble happens, maintenance staffs must go to the station to
repair the device where the interlocking device is installed.
Especially when interlocking devices are severely damaged by
lightning and/or disasters, it takes a lot of times to resume the
interlocking functions. In addition, when an interlocking device is
being replaced to a new device, a lot of works are required. For
example, the cables are usually connected directly with physical
devices such as track circuits, signal lights, point machines, etc.
These physical devices must change their connections into new
interlocking devices. After the connections are changed, many
verification processes are required. These maintenance and
replacing works will be especially difficult for the small railway
company, which has a limited number of staffs. It is required to
develop a mechanism to provide “Interlocking as a Service.”To
reduce the cost to replace and resume the interlocking functions,
interlocking devices should be separated from physical devices.
Then, interlocking functions will be realized under cloud
computing environment. When main interlocking functions are
separated from physical devices, it is expected to reduce the cost
of maintaining and/or replacing the interlocking devices. In
addition, this technology may open a business of “Interlocking as
a Service.”We draw an image of interlocking systems
implemented on cloud computing environment as follows.
Interlocking functions are implemented at the interlocking center,
which is a kind of data center operated by service provider
including signaling device manufacturer for small railway
operator, or by railway operators themselves. The interlocking
center can be placed relatively safe from disasters. When network
is affordable, the interlocking center can be distributed. Physical
devices such as track circuits and point machines will be
connected to the interlocking center via networks. The terminals
with physical devices will be installed at stations. The terminals
require fail-safe functions in case there is no command from
interlocking center. We consider two kinds of terminals; the one is
installed at signal houses as seen by traditional signaling
equipment, has the network interface and connected to physical
devices by cables. The other is implemented within the physical
devices. In this case network function is also implemented within
the physical devices. Radio connection is also possible. In this
case control commands will be directly issued to the physical
devices. When there is a trouble for some part of physical devices
or cables, temporal service is possible using radio based
connections.When the interlocking functions are implemented on
cloud computing environment, the cost of maintaining interlocking
devices will be reduced, because most of the maintenance work
will be executed at interlocking center. It is also expected to make
the interlocking devices resilient to the disaster, by moving the
function to the safe place against the disaster and/or preparing
redundant interlocking center. In addition, the cost of replacing
interlocking devices will be reduced in large amount, because the
replacement of interlocking devices will be possible just by
switching one virtual machine of interlocking functions to another.