Tadao Nakajima, a railway fan, was aiming for the Usui Pass between Yokokawa and Karuizawa on the Shinetsu Main Line. This film was taken in the cold of winter in December 1962.
Because the slope of the mountain pass is steep, an Abt method was adopted, in which a sawlike gear is moved to run the train.
It was also used for mountain trains in Switzerland, and was the only unusual method in Japan. When Mr. Nakajima heard the news about the switch to a new construction method, he and his friends went to shoot. In 1962, the year after this film was taken, the new method was adopted, but in 1997 the Shinetsu Main Line was discontinued with the opening of the Nagano Shinkansen. This is a very valuable historical record of the Abttype railway