[Alternative Bid for Construction of Seoul Subway Line No. 9 Lot 914]
2002.05.29 ~ 2002.09.09 / Seoul Metro, Daelim Industrial Co., Ltd.

Seoul Subway Line No. 9 connects the Gangnam Area of Seoul to the east-west rail network, and has a total length of 42.6km. Sambo Engineering provided design services for the 2,146m section of the line, located between Seocho and Gangnam Districts.

The original proposal was based on a construction method which caused disruption to the above ground traffic, and contained considerable economic risks. The issues were resolved by applying the results of the social cost analysis to determine the optimal construction method.

Tunnel safety was improved by modifying the alignment to bypass the Banpo Overpass, and Multiple Index (MI) for tunnel design was utilized to assess the tunneling methods. The main structures included stations 924 and 925, 3 drainage facilities, 4 ventilation and 2 air intake facilities, 1 pumping station, 440m of inflow and 700m of outflow pipes.