In mountainous Japan, whose ground is not solid enough, use of the 'distributed traction system,' in which motive power is distributed to each of the train-cars, as in electric train-cars and diesel train-cars, rather than the 'concentrated traction system,' in which a locomotive pulls passenger train-cars, is more suited.
地盤が悪く山がちな日本において列車を高速運転するには、機関車が客車を牽く「動力集中方式」よりも、電車・気動車のように編成の各車両に動力を持たせる「動力分散方式」の方が適している。