The first impression that people visiting Seoul by train encounter is the bustling Seoul Square and the busy interchange center with numerous cars. Under an ambitious plan to integrate around 10 bus stops near Seoul Station, the Seoul Station Bus Transfer Center was completed in 2009, accommodating over 90 bus routes and attracting an average of over 50,000 visitors daily.
 
However, both passengers and vehicles using the transfer center face many inconveniences. Bus platforms are scattered in various locations, causing confusion. Bus routes using platforms 5 and 6 cause severe traffic congestion as they turn around. Pedestrians are exposed to dangerous situations, having to cross a road over 110 meters wide, and are vulnerable to adverse weather conditions such as heavy rain, cold waves, and air pollution.
 
The aim of this project is to redevelop the vicinity of the transfer center to address the aforementioned issues. It involves relocating the above-ground lanes and concourse and covering them with a massive structure to improve traffic flow and pedestrian environment. The underground space will be expanded by extending Line 1 and enhanced for transfer convenience, while also accommodating commercial facilities to improve profitability and serve the users. The central part of the underground space will incorporate Sunken areas to allow natural lighting.
 
The structural design aims to minimize vertical members so that there is no interference with the movement of the ground level and at the same time develop ways to control the deflection of the roof level in large spaces. It is designed to satisfy serviceability by gradually taking steps from panel division/cutting, introduction/addition/deformation of truss, and utilization of new members. In addition, an Excel table was created to determine the buckling safety of the column and the bending/shear safety of the beam, and based on that, the tree column and the beam cross-section of the underground level were designed.
 
Environmental design focused on the solar radiation of platforms and the illumination of underground areas. At first, photovoltaic panels were installed on the roof to block the sunlight and produce electric power. Multi-Objective Optimization determined their location. Then, an optimal design was selected by comparing several Pareto optimal sets. An environment-evaluating index for the outdoor condition was used during the process.
 
Construction management (CM) aims to develop strategies to realize the project. Programs and business structures are planned to secure the necessary funds for the project. Based on this, the cash flow of the program is reviewed, and investment indicators are derived to assess the feasibility. Considering the constraint that traffic flow should not be disrupted during the construction period, major construction processes and schedules are established, and process charts are created.