KTX

KTX (Korea Train eXpress, Korean: 한국고속철도) is the first high-speed rail system in South Korea, and is operated by Korail. Construction began on the high-speed line from Seoul to Busan in 1992. KTX services were launched on April 1, 2004.

The KTX services now radiate from Seoul Station toward destinations across the nation, competing against SRT services from Suseo station, except Jungbunaeryuk Line which depart from Pangyo station.

The current maximum operating speed for trains in regular service is 305 km/h (190 mph), though the infrastructure is designed for 350 km/h (217 mph).

The initial rolling stock was based on Alstom's TGV Réseau, and was partly built in Korea. The domestically developed HSR-350x, which achieved 352.4 km/h (219.0 mph) in tests, resulted in a second type of high-speed trains now operated by Korail, the KTX-Sancheon, which entered into commercial service in 2010.

The next generation experimental electric multiple unit prototype, HEMU-430X, achieved 421.4 km/h (261.8 mph) in 2013, making South Korea the world's fourth country after Japan, France and China to develop a high-speed train running on conventional rail above 420 km/h (260 mph). It was further developed into commercialised variants, namely KTX-Eum and KTX-Cheongryong, with respective maximum service speeds of 260 km/h (160 mph) and 320 km/h (200 mph), which entered into KTX services in 2021 and 2024, respectively.

The Seoul–Busan axis is Korea's main traffic corridor. In 1982, it represented 65.8% of South Korea's population, a number that grew to 73.3% by 1995, along with 70% of freight traffic and 66% of passenger traffic. With both the Gyeongbu Expressway and Korail's Gyeongbu Line congested as of the late 1970s, the government saw the pressing need for another form of transportation.

The first proposals for a second Seoul–Busan railway line originated from a study prepared between 1972 and 1974 by experts from France's SNCF and the Japan Railway Technical Service on a request from the IBRD. A more detailed 1978–1981 study by KAIST, focusing on the needs of freight transport, also came to the conclusion that separating long-distance passenger traffic on a high-speed passenger railway would be advisable, and it was adopted in the following Korean Five Year Plan.

During the subsequent years, several feasibility studies were conducted for a high-speed line that aimed to reduce the travel time between Seoul and Busan to just 1 hour and 30 minutes. These studies yielded positive results. In 1989, after receiving the green light for the project, the necessary institutions were established to oversee its preparation. These institutions included the Gyeongbu High Speed Electric Railway & New International Airport Committee and the High Speed Electric Railway Planning Department, which was later renamed the HSR Project Planning Board. By 1990, the planned travel time between Seoul and Busan had been reduced to 1 hour and 51 minutes, and the project was scheduled to be completed by August 1998. and costs were estimated at 5.85 trillion South Korean won (₩) in 1988 prices, 4.6 trillion of which were to be spent on infrastructure, the remainder on rolling stock.