South Korea's Tunnel Innovation: The NGCS Revolution

South Korea's Tunnel Innovation: The NGCS Revolution

South Korea's mountainous terrain and dense urban areas have driven the nation to become a world leader in tunnel construction. Faced with the challenge of maintaining safety and comfort within its extensive tunnel network, the country has adopted forward-thinking pavement preservation strategies that are setting new global standards.

Historically, asphalt was the common choice for paving South Korean tunnels. However, recognizing the long-term benefits of concrete, the Korea Expressway Corporation (KEC) began a pilot program in 2014, introducing the Next Generation Concrete Surface (NGCS).

Preliminary tests of the NGCS during the pilot project, conducted by the Korea Highway Traffic Engineering Institute, demonstrated noise reduction of up to 7.5 dB(A) and enhanced surface friction, contributing to a safer driving experience.

The KEC now mandates NGCS, which combines diamond grinding and grooving, for all highway tunnels 500 meters or longer, marking a significant commitment to performance, durability and safety. This transition to NGCS reflects the opportunities created when the IGGA works with industry and government agencies. 

South Korea’s advanced approach is exemplified by a wide range of new and existing tunnel projects:

Sangju–Yeongdeok Expressway.

On this route, 206,000 m² of NGCS has been installed across 14 newly built tunnels, supporting the growing trend of concrete surfaces on expressways.

Donghongcheon–Yangyang Expressway.

With more than 235,000 m² of NGCS in four of its long tunnels—including Korea’s single longest highway tunnel, the Inje Tunnel—this expressway sets a benchmark for major infrastructure standards in new construction.

Busan Sanseong Tunnel. 

This three-mile urban tunnel in Busan features 66,000 m² of NGCS, aiding in noise reduction and safety despite city-center constraints.

Yeongdong Expressway and National Route 42. 

These preservation projects illustrate the versatility of NGCS on older tunnels. For example, the Yeongdong Expressway, originally opened decades ago, was resurfaced with 80,900 m² of NGCS in preparation for the 2018 Winter Olympics, enhancing ride quality in challenging weather conditions. National Route 42’s upgrade included more than 32,000 m² of NGCS to address truck noise and improve vehicle efficiency.

Anseong–Guri Expressway.

Opened in 2024, this 72.2-km route features 18 tunnels (30 km combined); 12 of them, stretching 27 km, were surfaced with 570,000 m² of NGCS, with an additional 1.1 km Han River bridge also treated.

Paju–Yangju Expressway.

Of the 19.6 km highway, tunnels and bridges cover 13 km. Five tunnels and four bridges—totaling 8.5 km—were finished with 120,000 m² of NGCS.

Changnyeong–Miryang Expressway. 

Out of 28.5 km, about 14.7 km of the expressway are tunnels. Of the six tunnels, three (totaling 9 km) were surfaced with 130,000 m² of NGCS, while the rest were treated with diamond grinding for improved service.

Suri Tunnel (Seoul Ring Expressway). 

This 1.9-km, eight-lane tunnel underwent a significant upgrade, with 51,000 m² of NGCS enhancing a critical beltway around Seoul.

Importantly, while full-depth repairs of concrete pavements are rare due to the relative youth of the infrastructure, hundreds of tunnels have already benefited from diamond grinding or NGCS as part of routine and preventive maintenance. This approach is recognized not only for achieving smoother, quieter surfaces but also for raising the bar in tunnel safety and long-term durability.

Pavement Preservation: A Global Imperative

From the advanced highways of South Korea to the complex urban networks of Australia—and across to the United States’ critical corridors like the Monitor-Merrimac Memorial Bridge-Tunnel in Virginia and Florida’s Port of Miami Tunnel—proactive pavement preservation stands as a cornerstone of modern infrastructure.



In the American examples, diamond grinding and targeted concrete restoration have played a crucial role in extending service life, improving skid resistance, and maintaining a smooth, safe ride for all users. Globally, techniques such as diamond grinding and the adoption of advanced surfaces like NGCS are not merely routine maintenance; they are strategic investments that protect the value and reliability of our most vital transportation links. This commitment sustains the operational life of critical tunnels, enhances safety and ride quality, and ensures that these complex structures remain dependable connections for communities and commerce for generations to come.

Visit www.igga.net to stay informed about the latest developments in infrastructure preservation and engineering excellence.