This map shows Korea’s longest expressway tunnel, 11-km-long Inje Tunnel, part of the Dong Hongcheon-Yangyang Expressway, now under construction.

To make Korean construction history, it is imperative to use the latest technologies and mobilize the industry’s best and safest workers. A little more than six years have passed since ground was broken for a project to build the 11 km-long Inje Tunnel, the nation’s longest expressway tunnel and the 11th longest one in the world. Next June, the tunnel, part of the Dong (East) Hongcheon-Yangyang Expressway now under construction, will be open to public traffic.

Despite the unprecedented sweltering heat that has hit the nation of late, construction crew members are putting final touches on the construction of what is dubbed a historic masterpiece to be remembered as a legacy of Korean construction history. 

A NewsWorld editorial team, escorted by an official of Daewoo E&C, recently toured the construction site to take a look at what is going on in the giant tunnel. 

Our team snuck into the tunnel aboard an SUV through a 1.4 km-long slide shaft that will be used for firefighting vehicles and will also supply fresh outside air into the tunnel. During our tour, construction crews were paving and putting the final products on the wall of the tunnel.

Construction crews are putting final touches on the giant Inje Tunnel.

The Inje Tunnel is going to set many records for the Korean construction history: mobilizing 45,000 workers for the construction of the tunnel, double the average of 22,000 and costing some 534 trillion won to construct, four times more than the average of 120.5 trillion won. The tunnel has a slide shaft in place that has contributed to halving its construction period from five years to two and half years. 

“I’m so honored to be involved in the construction of the 11-km-long Inje Tunnel, promising to be the nation’s longest expressway tunnel,” said Lee Yong-woo, general manager of Daewoo E&C and head of the construction site.

Chung Yeon-hoon, deputy general manager of the construction site, said, “I’m very thrilled to create a new thing.” He has been staying in the construction site for more than seven years since its groundbreaking to witness all the developments of the project. “At an early stage, I’d felt vagueness and the pressure in the heat, wondering what to do, but now I’m very proud of having almost achieving it.” Progress is now standing at 90 percent, he said. 

True to the hype of being the nation’s longest expressway tunnel, five consortium contractors have teamed up to make the Inje Tunnel, one of the nation’s best and safest tunnels. Daewoo E&C, the leader of the consortium, has a 50 percent stake in the project, which costs 520.1 billion won to build.  

It is noteworthy that the tunnel will be outfitted with outstanding and advanced ergonomics design features. 

Also installed are systems designed to ensure motorists’ safety and prevent possible disasters, General Manager Lee said. One of the outstanding features is choosing a slight curve instead of a straight line in order to prevent motorists’ dozing off while passing through the tunnel, equivalent to driving a distance between the Seoul Tollgate of the Gyeongbu (Seoul-Busan) Expressway and Shingal IC. The measure is based on the outcomes of an ergonomics simulation surveys of motorists. 

Dignitaries attend a ceremony to celebrate the penetrating of the Inje Tunnel under the Baekdu  Daegan on April 14, 2011.

The tunnel is designed with four landscape lightings to improve the safety of motorists. It is also outfitted with such ergonomically designed facilities as anti-freezing systems and remotely-controlled fog detection systems. 

The 1.4 km-long slide shaft and two vertical shafts are major features that are designed to prevent such disasters as fires. They will be in an integrated smoke exhaust mode. The tunnel has superb, advanced anti-disaster equipment and systems in place, ranging from fire detection to fire-fighting and smoke exhaustion to the prevention of secondary accidents and relief. At an initial stage, photo sensor fire detectors and detection systems for tunnel accidents are activated. Sprinklers are in place along the whole of the tunnel. There are also 10 pieces of foam mixing equipment, designed to address fires caused by petroleum vehicles and other large-scale fire accidents. Six automatic dampers and high-pressure precision sprinkler systems are in place to prevent secondary car pile-ups. 

Cross-passages for vehicles are in place to conduct salvage and rescue actions. Ten emergency cars in common ducts are in standby mode. Firefighting vehicles will be allowed to use the slide shaft to make it to accident sites quicker, while the slide shaft will be also used as a temporary shelter for motorists. Large-size vehicles will be diverted in the opposite direction through cross-passage ducts in the case of an emergency. Passages with double-layers doors for motorist will be installed at 37 locations. 

A top priority for Daewoo E&C’s is eco-friendliness in order to ensure the protection of the Baekdudaegan, a mountain range and watershed-crest-line that runs through most of the length of the Korean Peninsula, Deputy General Manager Chung said. 

Lee Yong-woo, general manager of Daewoo E&C and head of the construction site, gives a briefing on the progress of the construction of the Inje Tunnel. (Photos: Daewoo E&C, NewsWorld)

The passage of the tunnel is optimized based on geological features and the protection of the Baekdudaegan. The tunnel, passing through a maximum depth of 556 meters below the mountain range, is designed to go below only one stream. Such facilities as ventilation systems will be installed at a maximum of 500 meters from roads and residential areas. The tunnel is part of a project to build an expressway connecting Dong Hongcheon and Yangyang, which costs about 2.4 trillion won. When the expressway is opened to traffic as planned, it will serve as a shortcut between the Seoul metropolitan area and the East Coast. 

Motorists will likely see travel time between Seoul and Yangyang be shortened from the current two hours and 20 minutes to one hour and 30 minutes. The construction of the expressway will have an effect of saving 186 billion won in logistics costs annually and reinvigorating regional economies in inland areas of Gangwon-do and the East Cost. It will also boost the tourism industry in such tourist attractions as Mt. Seorak, Naksan Beach and the Naerin Stream.