the emu100 "electric express" was formally introduced on 15 august 1978 at a fare of nt$1.32 per kilometer. the first services operated between taipei and taichung (via coast line), and as electric catenaries were erected, switched to operating via mountain line. as the service was extended to chiayi and tainan, the service was formally christened "tze-chiang limited express". as electrification progressed, the service was eventually extended to between keelung and kaohsiung.