What speed did South Korea's HEMU-430X reach in 2013 testing?

South Korea’s HEMU-430X reached 421.4 km/h during testing in 2013.

The run was a major milestone for South Korean railway engineering. HEMU-430X—short for High-speed Electric Multiple Unit 430 km/h eXperiment—was developed as an experimental train intended to explore operation at around 430 km/h. Its record speed was recorded on conventional steel rails rather than a magnetic-levitation test track.

The train uses distributed traction, placing powered equipment along the train instead of concentrating most traction in separate locomotive cars. That arrangement can improve acceleration, weight distribution, and usable passenger space. The project involved the Korea Railroad Research Institute, Hyundai Rotem, and other Korean research and industrial partners.

The figure is a test speed, not the normal commercial operating speed of a passenger service. The “430” in the train’s name refers to its design target, while 421.4 km/h is the measured record achieved during the 2013 test campaign. It is also distinct from Korea’s in-service KTX trains, which operate at lower scheduled speeds.