HEMU-430X (standing for High-Speed Electric Multiple Unit 430 km/h eXperimental) is a South Korean high-speed train intended for a maximum speed of 430 km/h (267 mph). On March 31, 2013, it achieved 421.4 km/h in a test run, making South Korea the world's fourth country after France, Japan and China to develop a high-speed train running on conventional rail above 420 km/h.[3] The main new feature of the train compared to older South Korean high-speed trains is distributed traction. The commercial version of the train, tentatively named KTX-III, would have entered regular service in 2015 with a top speed of 370 km/h (230 mph), however as of 2019 the plan seems to be abandoned.[4]

HEMU-430X passing through Seodaejeon Station.
ManufacturerHyundai Rotem
Family nameHanvit
Number built1
Number in service0
  • TC: trailer car (unpowered driving trailer)
  • M: motorized intermediate car
  • MC: motorized trailer car (powered driving trailer)
Line(s) servedGyeongbu High Speed Railway
Honam High Speed Railway
Car body constructionAluminum, composite[2]
Train length147.4 m (484 ft)
Car lengthEnd cars: 23.5 m (77.1 ft)[2]
Intermediate cars: 25.1 m (82 ft)
Width3,100 mm (122.0 in)[2]
Height3,720 mm (146.5 in)[2]
Maximum speedPlanned in tests/design:
430 km/h (267 mph)
Planned in service (KTX-III):
350–370 km/h (217–230 mph)
WeightAxle load: max. 14 t (15.4 short tons; 13.8 long tons)[1]
Traction system18 three-phase asynchronous induction motors and permanent magnet synchronous motors
IGBT-based VVVF inverters[1]
Power output20 x 410 kW (550 hp) (8.2 MW or 11,000 hp)
Acceleration0.5 m/s2 (1.8 km/(h⋅s)) up to 150 km/h (93 mph)[1]
0 to...
  • 300 km/h (186 mph): 230 s and 11.67 km (7.25 mi)[1]
  • 0 to 350 km/h (0 to 217 mph) in 346 s and 22.27 km (13.84 mi)[1]
  • 0 to 400 km/h (0 to 249 mph) in 673 s and 56.98 km (35.41 mi)[1]
Electric system(s)25 kV/60 Hz AC overhead line[1]
Current collection methodPantograph[1]
UIC classification2'2' + Bo'Bo' + Bo'Bo' + Bo'Bo' + Bo'Bo' + Bo'Bo'
Braking system(s)Eddy current, regenerative, rheostatic, disc
Safety system(s)TVM 430, ATP, ATC
Multiple workingYes[1]
Track gauge1,435 mm (4 ft 8 12 in) standard gauge


The original 1991 plan for the Korea Train Express (KTX) high-speed rail system foresaw an operating speed of 350 km/h (217 mph) to enable a travel time under two hours between Seoul in the northwest and Busan in the southeast of South Korea, the terminuses of the first line.[5] Later, planned top speed was reduced to the 300 km/h (186 mph) maximum of existing high-speed trains on the market.[5] Korail then ordered high-speed trains on the basis of Alstom's TGV Réseau, the KTX-I, which started KTX service on April 1, 2004,[6] and operate at a top speed increased slightly to 305 km/h (190 mph) in November 2007.[7]

In a project South Korean government research institutes and rail industry companies launched in 1996 to fully localise high-speed rail technology, the know-how gained in the technology transfer for the KTX-I was used as the basis to develop the experimental train HSR-350x,[8] which was to be tested at up to 385 km/h (239 mph) so that the commercial version can have a top speed of 350 km/h (217 mph).[9] However, the maximum speed achieved in the HSR-350x tests was 352.4 km/h (219.0 mph) on December 16, 2004;[10] and the design and top speeds of the commercial version, the KTX-II (KTX-Sancheon) were set to be the same as those for the KTX-I.[11]

The aim to develop commercial trains with a top speed of 350 km/h (217 mph) was taken up again in the project to build another experimental train, the HEMU-400X (High-speed Electric Multiple Unit - 400 km/h eXperiment), which was launched in July 2007.[12] The six-year project schedule was originally set to last until July 2013, and involved 100,000 km (62,000 mi) of test runs with speeds reaching 400 km/h (249 mph).[2][13] The project is led by the Korean Railroad Research Institute (KRRI) and Hyundai Rotem, and also involves the Korea Institute of Construction & Transportation Evaluation and Planning (KICTEP),[12] 20 other companies, 13 universities, and one other organisation.[2] The project budget was set at 97.11 billion won, with a government contribution of 69.2 billion won.[2]

Following a call by Nam-Hee Chae, the president of the Korea Railroad Research Institute, for proposals for a generic name for Korean-made high-speed trains,[14] on April 5, 2007, Chae announced the name Hanvit (Hangul: 한빛),[15] which means a streak of intense light in Korean.[9] Under the new naming scheme, HEMU-400X is also called Hanvit 400.[15]

The preliminary design was presented to the public in May 2009.[16] A full-scale mock-up of an end car was first shown in June 2009 at the RailLog 2009 exhibition in Busan.[17] Detailed designs were presented in October 2010,[1] when the prototype was expected to be completed in 2011 and start line tests in 2012.[18]

HEMU-430X prototype

A prototype, named HEMU-430X was unveiled in May 2012. The unit is expected to undergo around 100,000 km of testing up to 2015.[19]

Technical details

In contrast to the articulated passenger coaches between traction heads configuration of the KTX-I, HSR-350x and KTX-II trains, the 6-car HEMU-400X is fitted with distributed traction: traction equipment is underfloor and all axles of all four intermediate cars are powered.[20] The detailed plans released in October 2010 changed the trailing end driving trailer of the experimental train into a powered car, deviating from the planned commercial version.[1] The new high-power configuration is to provide for higher acceleration:[2] the 8-car commercial configuration was calculated to reach 300 km/h (186 mph) in less than four minutes and less than 12 kilometres (7.5 mi); the top test speed of 400 km/h (249 mph) is to be reached in 673 seconds and 56.98 kilometres (35.41 mi).[1] Similarly to JR East's Fastech 360 programme, the plan is to develop and test both asynchronous induction motors and permanent magnet synchronous motors in the train.[2]

Research in the G7 programme showed that the bulk of the longitudinal aerodynamic resistance (drag) of the pantograph and the largest component of vertical aerodynamic forces (lift) acting on it derive from the contact shoe.[21] For the HEMU-400X, researchers developed an aerodynamically optimised contact shoe cross section that reduced drag by about 40% and lift amplitude by about 25% in comparison to the contact shoe of the KTX-II pantographs.[21]

The train is designed with active suspension for increased ride comfort.[2] To save weight, in addition to aluminum, composite materials are to be used in the carbody.[2] The development of new transformers, batteries and a number of other electric system components also focuses on reducing weight and size.[2] The train is also intended as basis for Rotem to compete in high-speed train tenders abroad, and is designed to conform with European high-speed rail standards.[2]

Nose styling was designed using a genetic algorithm, starting with the hybridization of the nose shapes of existing French TGV and German ICE high-speed trains.[22] A double-deck configuration was also considered.[22]

In the experimental train, the first two cars will test first class seating, the fourth car will be fitted out with a bar and special passenger compartments, the fifth car will test standard class seating.[1] Data acquisition equipment for the on-board measurements are foreseen in the third and sixth cars.[1]

Commercial version (KTX-III)

KTX-III, the commercial derivative of HEMU-400X, is expected to enter service in 2020.[16] In normal 8-car, 197.6 m (648 ft) configuration, KTX-III would consist of two driving trailers at either end and six motorized intermediate cars giving 9.84 MW of power,[1] with an option of extension to 10 cars.[16] The second, fourth and seventh cars will house transformers, each connected to inverter groups on the neighbouring third, fifth, respective sixth car.[1] The end cars will house the batteries, while pantographs will be installed on the extreme intermediate cars.[1]

The goal for maximum operating speed was originally 350 km/h (217 mph), which was expected to enable Seoul-Busan travel times of 1 hour 50 minutes.[16] In plans released on October 2010, planned service speed was raised to 370 km/h (230 mph).[1] In the default configuration, the first two cars will be first class with 2+1 seating, the third car will house a bar and special passenger compartments with facing pairs of 3 or 2 seats, the fourth to eighth cars will be standard class with "3" seating, with foldable seats offering altogether 378 seats.[1]


  1. "High Speed Trains". Hyundai Rotem. October 2010. Archived from the original on 2011-07-22. Retrieved 2010-11-23.
  2. "최고시험속도 400km/h 동력분산식 차세대 고속열차 개발(HEMU-400X)". Korean Rail Technology (in Korean). January–February 2009. Retrieved 2010-11-13.
  3. "차세대 고속열차 최고시속 421㎞ 기록".
  4. "[단독] 2000억 틸팅열차·해무열차, 사실상 차량기지에 방치" [200 billion tilting trains, Hemu trains, virtually left at the rail yard]. JoongAng Ilbo. October 2, 2018.
  5. Cho, Nam-Geon; Chung, Jin-Kyu (2008). "High Speed Rail Construction of Korea and Its Impact" (PDF). KRIHS Special Report Series. Korea Research Institute for Human Settlements. 12. Archived from the original (PDF) on 2011-05-29. Retrieved 2010-11-14.
  6. "SNCF International in South Korea" (PDF). SNCF. May 2008. Archived from the original (PDF) on 2011-07-24. Retrieved 2010-08-27.
  7. "KTX 속도 시속 5km 빨라진다". JoongAng Ilbo (in Korean). 2008-11-26. Archived from the original on 2011-07-13. Retrieved 2010-11-05.
  8. Lee, Hisung; Moon, Dae-Seop (2005). "Next Generation of Korea Train Express (KTX): Prospect and Strategies" (PDF). Proceedings of the Eastern Asia Society for Transportation Studies. 5: 255–262. Retrieved 2010-09-01.
  9. Kim, Kihwan (May 2008). "Korea develops high-speed ambitions". International Railway Journal: 35–36. Retrieved 2010-11-04.
  10. "Trans-Korean Railway" (PDF). Korean Rail Technology. 1: 4–5. May–June 2005. Retrieved 2010-11-04.
  11. "KTX 개통 5주년 보도자료" (in Korean). Rail Safety Information System. 2009-04-01. Archived from the original on 2010-11-11. Retrieved 2010-11-13.
  12. "400 km/h High-Speed Train to be Unveiled by 2012". Next-Generation High-speed Rail Technology Center. 2009-09-21. Archived from the original on 2011-07-22. Retrieved 2010-08-28.
  13. "Project Overview". Next-Generation High-speed Rail Technology Center. Archived from the original on 2011-07-22. Retrieved 2010-09-01.
  14. "HSR350x looking out for name". KRRI. 2006-05-04. Retrieved 2010-11-21.
  15. 한국형고속열차 네이밍 (in Korean). Chae, Nam-Hee. 2007-04-05. Archived from the original on 2011-07-08. Retrieved 2010-11-20.
  16. "[주간조선] KTX 진화를 거듭하다". The Chosun Ilbo (in Korean). 2009-06-09. Retrieved 2010-09-02.
  17. "Korean high-speed train business team visits Brazil". Newsletter. Hyundai Rotem. August 2009. Retrieved 2010-11-24.
  18. "Korea's HEMU-400X high speed train to roll in 2011". Railway Gazette International. 2010-10-27. Retrieved 2010-10-30.
  19. "Experimental 430 km/h high speed train unveiled", www.railwaygazette.com, 18 May 2012
  20. "Development of EMU prototype train technology (II-1)". Next-Generation High-speed Rail Technology Center. Archived from the original on 2013-01-12. Retrieved 2010-09-01.
  21. Lee, Yeongbin; Rho, Joohyun; Kwak, Minho; Lee, Jaeho; Kim, Kyuhong; Lee, Dongho (2009). "Aerodynamic Characteristics of High Speed Train Pantograph with the Optimized Panhead Shape" (PDF). Proceedings of the 7th IASME/WSEAS International Conference on Fluid Mechanics and Aerodynamics. pp. 84–88. Retrieved 2011-02-16.
  22. "차세대 고속열차 HEMU-400X 차량 디자인". Korean Rail Technology (in Korean). January–February 2009. Retrieved 2010-11-13.
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