The KTX high speed train zips along near Banwol Station, Ansan, Gyeonggi-do.
OK, it’s not exactly the shinkansen tearing past Mt. Fuji. On the other hand, it’s better than getting kicked in the nuts.
The spot is a place KORAIL is now promoting as a “famous photo spot,” with posters in many of Seoul’s subways. If by “famous photo spot,” they mean “need to cut through somebody’s farm and hike through bushes and thorns along a barbed wire fence to a spot above a tunnel where you might be able to poke your camera through the fence and take a shot if you don’t mind the overgrown vegetation in front of you,” then yes, it’s a “famous photo spot.”
And no, there are no signs pointing to the spot. Or even a proper path. The locals are friendly enough and try to point you in the right direction, but very few of them seem to know where the actual point is exactly. If you’re thinking of taking this shot—and until KORAIL cleans up the vegetation on top of the tunnel and perhaps builds a proper path and/or viewing platform, I’m not sure I can recommend it—the “path” is in back of a chicken farm on the other side of a railroad culvert near the Banwol Reservoir.
For those keeping score at home, Korean Wikipedia says Korea has 1192.9 km of high-speed rail. Current KTX trains operate at a maximum of 305 km per hour, but the development of the next-generation HEMU-430X makes Korea only the fourth country in the world with trains that can run at 420 km per hour or above.