Like many formerly colonized countries, railways in Korea were the spearhead of colonialism. Every attempt by the Korean Empire to build its own railways failed, and the core rail network was ultimately constructed under Japanese imperialism to use Korea as a strategic bridge to the continent. Railways were both the centerpiece and the practical instrument of colonial rule. Even in Seoul today, three of the four bridges that make up the Hangang Railway Bridge, as well as Seoul Station?which marks its 100th anniversary this year?are products of Japanese colonialism.

Moreover, Korea's rapid economic growth was achieved alongside the expansion of expressways. The catalyst that transformed the southeastern farmlands of Seoul into the new urban center of Gangnam was the Gyeongbu Expressway, which opened in 1970. Beginning with that road, Korea's expressway network surpassed the railway network in length within a single generation and, even now in 2026, remains more than 20 percent longer. This is a phenomenon unseen even among other major automobile-oriented countries.

Meanwhile, railways in the Seoul metropolitan area and across Korea remained largely stagnant. After surpassing 3,000 kilometers of national operating track in 1961, it took another 61 years to exceed 4,000 kilometers. The metropolitan commuter rail network has yet to reach 1,000 kilometers, even 52 years after its launch in 1974. The gap was filled by the urban rail system built by the Seoul Metropolitan Government. The first-generation network, consisting of Lines 1 through 4, was built between 1974 and 1985 during Seoul's explosive growth period. The second-generation network, consisting of Lines 5 through 8, was constructed in the 1990s as Korea entered middle-income status and Seoul's population growth began to plateau. In the 21st century, a third-generation network, centered on Line 9 and the light rail lines, was added. Thanks to sustained investment, Seoul's urban rail network is now nearly twice as long as its urban expressway network.

However, because urban rail lines stop frequently to connect neighborhoods evenly throughout the city, they are far too slow to effectively serve either the metropolitan network linking Seoul with its satellite cities or the national network connecting Seoul with major cities across the country. Yet in the era of expressways, as competition with automobiles intensified, metropolitan and national rail networks became structurally prone to long-term deficits. Although only the state could build such networks, the government largely abandoned railway development during the high-growth decades of the late 20th century. Consequently, Seoul's metropolitan and national rail systems remain less developed than its urban rail network.

For example, trains traveling between Seoul and most parts of the country departed from and arrived at Seoul Station for nearly a century. This remained true until the introduction of high-speed rail in the 21st century. Even today, Seoul Station's status is irreplaceable. The combined scale of all other terminal stations is smaller than that of Seoul Station alone. Furthermore, valuable inner-city rail infrastructure was sometimes sacrificed, as seen when Seongdong Station (located near today's Jegi-dong) on the Gyeongchun Line was abolished in 1971. The metropolitan rail network also fell short of expectations. Even in the first-generation new towns, built 20 to 30 kilometers from central Seoul and requiring express services to the city center, only all-stop trains were operated, identical to the urban rail lines. This was because neither quadruple-tracks nor even adequate passing tracks could be secured.

These shortcomings become even more apparent when contrasted with other megacities. Compared with older megacities that have longer development histories, Seoul's capacity to handle national rail services is significantly lower. London has 11 stations comparable to Seoul Station (with its 15 platforms and 3 double-track through lines), Paris has 7, and Moscow has 9. In Chinese megacities, many of which began expanding their rail networks later than Seoul, major stations have been established in each cardinal direction, and many possess nearly twice the number of platforms and mainline tracks available at Seoul Station. The contrast is equally striking in metropolitan rail networks. Tokyo has 37 double-track railways crossing its boundary and connecting the suburbs with the city center, roughly twice Seoul's 18 as of 2019. London has 53 such corridors, nearly three times Seoul's number.

To better understand these differences, I collected relevant data and developed an index system to enable comparison among the rail networks of approximately 50 megacities worldwide, including Seoul. Think of it as treating each city as one of 50 students taking a course called "Railways," and evaluating the scale and structure of their networks based on the question of how well, and with what quality, they have built rail connections at urban, metropolitan, and national levels, given their respective conditions. In this "Megacity Railway Development Index," as of 2019, Seoul ranked roughly 20th. Metaphorically speaking, that is equivalent to a B-minus grade.

Ahead of Seoul are the developed nations that have been building railways since the early 19th century, namely, the megacities of Europe and Japan. Surrounding Seoul are the megacities of China and the United States. China's rail systems are expanding at an astonishing pace, while many American megacities struggle to modernize railway infrastructure that is more than a century old. Behind Seoul stand the giant cities of India, South America, and Africa. Even at this very moment, enormous populations are pouring into these cities, but the means of mobility required for these populations remain insufficient. While many cities continue to expand their rail networks incrementally, many others effectively abandoned theirs, leaving them unused and giving them an F grade.

Looking at the landscapes of world megacities through the lens of railways allows us to roughly sketch not only Seoul's past and present, but also its future. Having acquired railways since the final year of the 19th century and having secured a relatively generous standard-gauge track for connections with continental networks, Seoul was in a less favorable position than the imperial centers, China, or India, where railway networks were established from the early to mid-19th century. However, it was in a better position than colonies in Africa and Southeast Asia, which acquired networks in the 20th century that were fragmented and built quickly at low cost. Furthermore, thanks to the economic density concentrated in Seoul, consistent investment in urban and metropolitan rail proceeded even during the nationwide rapid growth era, when railways were largely abandoned, laying the groundwork for citizens to regard the railway as an indispensable means of mobility.

Upon these rail networks, Seoul's 21st century is flourishing. For centuries, the city maintained an overcrowded monocentric structure concentrated within the historic city walls. The opening of Line 2 created the space for Seoul to evolve into a polycentric city. Railways enabled not only major shifts in population and industry but also experiments in lifestyle and culture. Since much of the younger generation lives without cars, the spaces where these cultural experiments took place naturally emerged around railway stations. In the 1990s, Generation X culture made the Sinchon and Ewha areas shine along Line 2. In the 2000s, Millennial culture found its center in the Hongdae, Hapjeong, and Sangsu area, reinforced by the opening of Line 6 in 2000. In the 2020s, the cultural energy of the MZ generation gathers in Seongsu-dong, riding the Bundang Line, which connected with Line 2 in 2013. The cultural energy of the next generation will likewise flow along the rail network and gather somewhere else in Seoul.

Every city possesses its own strengths and weaknesses. Just as an ancient, long-standing tree bears many knots and asymmetries accumulated over time, Seoul's railway network has grown alongside the city's history and bears the marks of the many experiences accumulated throughout its growth, much like the knots of an ancient tree. From the end of the 20th century through the first quarter of the 21st century, despite historical limitations and its reputation as a declining industry, Seoul's railway has steadily accumulated investment. It carved out its own niche amid the powerful dominance of the automobile and prevented the city from suffocating under the immense pressure of tens of millions of daily commutes. Thanks to this accumulated rail network, Seoul has become the only city in Korea to achieve reductions in greenhouse gas emissions from the transportation sector. In the face of the polycrisis confronting our cities, including climate change, if citizens who continue to cherish and protect Seoul are to emerge, Seoul's railway will be at the very foundation of that effort.