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We monitor Line 9 operation, systems, and facilities all the time during the operating hours. In case of
abnormalities, we follow swift measures to control and instruct the onsite office not only to prevent
accidents or minimize casualties and damages for the safety of customers and workers, but also to
normalize operation as quickly as possible. In between operating hours, we prepare for safe operation,
inspect monitoring systems, control onsite works, and address various safety-related issues.

Operation Control System is designed for safe operation and efficient management of rolling stocks and
consists of Total Traffic Control(TTC) System, Supervisory Control and Data Acquisition (SCADA) System,
Telecommunication System, and Automated Machinery Control System.

Operation Control Center performs “Driving Control” for general operation of rolling stocks,
“Signal/Telecommunication Control” for customer information, subway signals and telecommunication
systems, “Electrical Power Control” for stable power supply, and “Machinery Control.”

• Total Traffic Control(TTC) System

Total Traffic Control(TTC) in Seoul Metro Line 9 is designed for Operation Control Center to control and
monitors all 25 stations of Line 9 (Gaehwa-Sinnonhyeon), the depot, incoming/outgoing tracks, and
connections to Incheon International Airport Railroad. For these purposes, TTC’s application software
monitors subway operation in real-time, automatically controls operation according to schedules, manual
operation of driving operators, train tracking, and TTC facilities. It also supports continuation, stability,
speed, and convenience of operators. Traffic Control Computer (TCC) is the main server for TTC System
that steers all of the major operation tasks and is required to operate properly even with hardware or
software problems. The computer itself is built with redundancy for the auxiliary parts to take over the
operation without data losses in case of problems with the main parts.

Line 9 constantly transmits information on track conditions, the following station, destinations, and
stopping positions for operators to follow directions and prevent mistakes.

The Electronic Interlocking System automatically controls the course of rolling stocks to prevent collision. With electronic circuits and computers, it ensures safe operation of rolling stocks and shows better
performances than the traditional relay type or the systems of other subway likes. The most important parts of the system have adopted the high-reliability multiple connection type to improve reliability and safety of
operation.

The routes selected by the Electronic Interlocking System directly control subway operation to control
speed, stopping position, and inter-station operation. The courses are also built with the high-reliability
multiple connection type ensure backup in case of problems, as well as reliability and safety. Other safety features include maintaining appropriate distances between cars (safety distance). If another car
approaches within the safety distance or in any other abnormal situations, the car automatically stops for
the safety of passengers.

• Telecommunication System

Line 9 houses all data needed to control all essential power, signal, guiding, and security devices for the operation of rolling stocks in a system of digital optical transmission facilities. This means that all essential control signals for the operation of rolling stocks are transmitted through this line.

Telecommunication Facilities for Operation Control	Telecommunication Facilities for Management	Telecommunication Facilities for Maintenance	Telecommunication Facilities for Women and the Disabled
Digital Transmission Facilities	Electronic Exchange Facilities	Uninterruptible Power Supply	Call Phone
Wireless Facilities	Fax	Wayside Telephone	Guiding System
Video Transmission Facilities	Train Destination Indicator	Talk-Back Device
Control Phone Facilities
Automated Broadcasting Facilities
Paging Phone



• Supervisory Control And Data Acquisition (SCADA) System

Subways are powered by Korea Electric Power Corporation. Subway stations have exclusive substations and lines to supply alternating current (AC) at 22.9kV. Subway substations have dual transmission lines to maintain uninterruptible conditions under any circumstances. This means that other substations can
extend supply when a substation shuts down. Also, each station has electrical rooms to supply power to
the amenities. Even if a station is completely blacked out, emergency guiding lights will be always on to
guide passengers for safe evacuation.

SCADA System allows Operation Control Center to monitor and control the overall power system of Line 9. It not only controls sudden disconnections and switch functions in normal operations, but it also monitors various system conditions, protective relays, and other major equipment.

• Automated Machinery Control System

Automated Machinery Control System uses high-performance computers to remotely control and monitor
HVAC/ventilation, sanitary water supply/sewer, fire extinguishing, transport, and PSD (Platform Screen
Door) facilities in each station or tunnel. Line 9 Automated Control System is not only separately controlled by each Direct Digital Controller to maximize efficiency, but it also operates other advanced safety devices, such as enthalpy control (cooling efficiency), smoke control (prevents smoke from spreading in fire), and signal control.

In case of a fire, the signal detected by each station’s receiver is interlocked with Automatic Control System
to enter smoke control mode. This triggers smoke control fans and other fans above the tracks to operate to
discharge smoke. This system operates automatically in case of a fire.