an older or pre-existing rail line, as opposed to any newer line servicing the same area / the non-bullet train JR railway lines, the regular train lines as opposed to the shinkansen

wire diameter

underground line, specifically an underground cable or wire

X-ray (short wavelength electromagnetic radiation) / X-ray (photograph made with X-rays)

(geography) Arctic Circle (one of the five major circles of latitude)

coastline, shoreline / a railroad that follows a coastline

fuse (cord)

steel wire/cable

finish line

(geography) a tropic