Global SAE-A Group
Seoul 923
Subway Station
The most challenging subway project ever. The construction site for Line 9 was just 15 centimeters from existing Line 3.
Despite difficulties at every turn, we completed the Express Bus Terminal Station with outstanding technology and construction expertise, marking the beginning of Phase 3 of the Seoul Metro.
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Location
Seocho-gu, Seoul
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Completion
DateJuly 2009
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Client
Seoul Metro
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Project
OverviewTotal Length(1.78km)
- Main line: Underground box structure via open-cut method 557.5m, Tunnel 850m
- Main line: Opening 172.5m, Tunnel 200m
- Main line ventilator: 7 locations
Challenging the impossible
Challenge
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ChallengeChallenging the impossible
Go beyond limits, achieve the impossible, and prove world-class construction.
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World Class Proven in Numbers
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First in the world to apply
TRcM and CAM
1st
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Gap from Line 3
15cm
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Total
construction cost
180billion won
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Transfer line(Subway Lines 3, 7, and 9)
3
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Total construction period
80months
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Construction section
1,780m
Seoul 923 Subway Station is a complex transfer station located in Banpo-dong, Seocho-gu, Seoul.
As a large-scale transportation hub where Lines 3, 7, and 9 meet, it was the most difficult project in Korea to build a new Line 9 tunnel with only 15cm from the existing Line 3 tunnel. Based on creativity and passion, Ssangyong E & C created another legend by simultaneously applying TRcM and CAM methods for the first time in the world
Total Design Concept
A precise and beautiful civil engineering structure
made by human
During the construction of the Seoul Subway Station 923 located beneath the Gangnam underground shopping mall, tunneling was chosen over open-cut method due to the sensitive location.
Different techniques were applied for the soft ground above and bedrock below to secure a large space. Notably, high-precision jacking of 2-meter-diameter steel pipes ensured both construction stability and a clean finish.
Precise & Beautiful civil engineering
Total design concept applied for the first time in Korea
This is Korea’s first case to introduce the concept of 'total design', integrating architecture, lighting, signs, benches, and flooring into one unified design language.
The project enhances user experience through harmonious function and aesthetics, with refined colors and forms offering visual comfort—significant as it unifies previously fragmented design elements into a consistent style.
Overcoming Complex Soil and Rock Layers with Precision
Using existing methods, construction at intervals of only 15 cm was nearly impossible. To minimize the impact on surrounding facilities, we applied the TRcM method of installing walls and excavating a tunnel, building a tunnel-type structure.
The CAM method, used alongside TRcM for the first time in Korea, involves pressing 10–13 large 2m-diameter steel pipes along the subway path, filling them with rebar and concrete to form a support structure, then excavating beneath.
To withstand the high pressure generated during the hydraulic insertion of the steel pipes, a 1,000-ton reaction wall was constructed at the launch base, enabling safe and efficient construction even within confined spaces.
To block groundwater inflow during the construction of steel pipes, we installed a waterproofing wall, and minimized settlement that could affect surrounding structures by installing both drainage pipes and reinforcement grouting.
Ssangyong E&C's awards draw international acclaim
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2009
Brunei Medal from UK Institute of Civil Engineers
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2009
Selected as Good Design (GD)
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2009
Korea Civil Engineering & Architecture Awards (Civil Engineering Category Excellence)
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2009
The Annual Civil Works Awards (Grand Prize)
* Brunei Medal from UK Institute of Civil Engineers
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