Foreigners are struck by how clean a subway system can be when it carries 6.6 million passengers a day. Those who have ridden the New York, London and Paris subways tend to react most strongly.
Seoul's subway lines 1 through 8 carried 2.41752 billion passengers in 2024, or an average of 6,605,250 a day, the Seoul Metropolitan Government said on the 6th. That places it among the world's largest subway systems, alongside New York and Tokyo. Maintaining cleanliness on that scale is what has drawn attention from major cities around the world.
CNN described the Seoul subway as "impeccably clean, efficient and safe," reporting that many experts rank it as the best subway system in the world. On TripAdvisor, travelers who have used the London, Paris, New York and Tokyo subways have left a string of reviews saying Seoul is by far the cleanest of them. Some wrote that it is "cleaner than my own home" and that "even the restrooms are impeccable."
At the heart of the system's cleanliness are platform screen doors. Starting with Sadang Station in 2005, the city installed the doors at stations one by one and completed work at every Seoul subway station in 2009. In the United States and Europe, by contrast, most stations still lack them.
The doors block the path through which pollutants and dust from the tracks flow onto platforms as trains pull in. City measurements showed that fine dust concentrations at subway stations fell about 20% to 86.5 micrograms per cubic meter after installation, from 106.7 micrograms before. Platform noise dropped 7.9% to 72.1 decibels from 78.3 decibels.
The gap also shows up in infrastructure. In a survey comparing subway systems worldwide, only two — Shanghai and Seoul — offered accessibility facilities for people with disabilities at 100% of their stations. New York stood at 25%. The Seoul subway won the top prize in the ticketing technology category at the 2024 Transport Ticketing Global Awards in London and also received a Red Dot Design Award, earning international recognition for both technology and design.
Behind the cleanliness is structural investment. Although the Seoul subway opened more than 50 years ago, it has continued to add advanced features such as platform screen doors, Wi-Fi, heated seats and real-time crowding information. Unlike subways in Western countries with longer histories, Seoul built out its network relatively late, allowing it to be designed to modern standards from the start — an advantage, according to analysts.
