Gangnam Intermodal Transit Center is more than just an underground transportation station that will house three high-speed train lines and two subway stations in southern Seoul. For acclaimed architect Dominique Perrault, it is more of a social project.

“It is not a project to build an underground tunnel. Architecture is part of culture. The space should be a quality public space where people want to come, not a damp and dark underground space,” the architect said in an interview with The Korea Herald in Seoul on Oct. 28. He spoke in French with a Korean interpreter.

The project, which won an international competition in 2017, has been mired in trouble as its construction costs have far exceeded the city budget, which was set at around 600 billion won ($463 million), according to Seoul-based Junglim Architecture involved in the project. The total cost for the project, including the engineering works, is around 1.5 trillion won.

Although the primary function of the space is a transportation hub, the 167,000-square-meter underground station is also a public space, and will feature a large square on the ground, a huge exhibition space and a multitude of spaces for work. Some 600,000 people are expected to use the underground space daily.

For Perrault, the natural light that permeates the underground space is the key which will differentiate the underground space from other such spaces.