[Design/Construction Package for Improvement of Namsan 2nd Tunnel]
1997.05~1998.10 / Seoul Metropolitan Construction, Hyundai Construction

The Namsan 2nd Tunnel, connecting Yongsan and the Central districts of Seoul, was the first large-scale tunnel improvement project. Adoption of advanced construction technologies enabled improved technical level of services, decrease of design and construction period, and minimization of accidents. Sambo Engineering performed the detailed design for the 1,816 m section, which included the 1,621 m long tunnel. The project included removal and replacement of the internal structures, concrete lining, pavement, portals, maintenance office, ventilation ducts, electric equipment and fire safety equipment in the tunnel, as well as reinforcement of the walls and improvement of the aesthetics. During the removal of the ceiling concrete lining, the structure was reinforced, and an excavation method selected to minimize impact from the removal works. This improved the workability, economy, safety, and environmental friendliness of the construction. By using the HRB construction method, environmental damage, noise and vibration were minimized or prevented. Asphalt-concrete mix was used for road surface, and the median divider was raised by 30 cm to improve safety between the traffic directions.