PyeongChang Behind the Scenes: Underground Works for Public Transportation

The GangNeung tunnel in its finishing stages (Photo: Korea Rail Network Authority).

The Olympic Games always shine a light on the host city and country, and on their ability to host such an event. The XXIII Winter Olympic Games in PyeongChang, South Korea, have come to an end, and as the glare fades, we can look back at some of the infrastructure work that was done to make the games possible.

Located in Gangwon Province with its capital at Chunchen, the county of PyeongChang is bounded on the east part by the East Sea (Sea of Japan). The province’s harsh landscape is dominated by Taebaek Mountains where many ski resorts exist as well as Buddhist temples.

As part of Korean government’s effort to expand transportation infrastructure for the Olympics, Korea’s high-speed railway system, known as Korea Train eXpress (KTX), has been extended to PyeongChang for the Olympics by constructing new line: GyengGang Line.

Due to the mountainous topography of Gangwon Province, the KTX extension project consisted of construction of 34 tunnels, totaling 76 km in length, including two major tunnels: DaeGwanRyeong tunnel and GangNeung tunnel.

DaeGwanRyeong Tunnel

The DaeGwanRyeng tunnel, 21.7 km in length, was constructed by drill-blast and is the longest railway tunnel in Korea and the eighth longest mountain tunnel in the world. In order to minimize environmental impact to Taebaek Mountains, the tunnel was constructed at an average cover depth of 400 m with a maximum depth of 700 m.

The tunnel excavation work began in June 2012 and was completed in November 2015 with a total construction cost of $500 million (USD). This project was separately awarded to three consortiums: Hyundai E&C, Halla Corporation, and Samsung C&T, by Korea Railway Network Authority (KRNA), the owner, on a design-build basis.

GangNeung Tunnel

GangNeung tunnel is the last tunnel to have been completed along the stretch of the extension project. The total length of the tunnel is 2.8 km and runs across the GangNeung city center. A 1.2-km long section is an underwater tunnel excavated though the riverbed of NamDaeChun river using an 8.4-m diameter slurry shield TBM with an average depth of 37 m.

This project was awarded to Samwhan Corporation consortium by Korea Railway Network Authority (KRNA), the owner, on a design-build basis. The tunnel excavation work began in November 2015 and was completed in October 2016 with a total construction cost of $120 million (USD).

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The new GyengGang Line is now 120.3 km long and operates from Seoul to GangNeung and connects Incheon International Airport to GangNeung station within two hours, providing more than 50% time saving compared to other transportation options.

This article was contributed by the International Tunnelling and Underground Space Association (ITA).

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