Yamasen Railway Bridge 山線鉄橋

A vermilion iron bridge spanning the Chitose River — the outflow of Lake Shikotsu — located in the lakeside area of Shikotsu Onsen. The bridge was originally erected in 1899 (Meiji 32) across the Sorachi River as a railway bridge, then relocated in 1923 (Taisho 12) for use by the Oji Paper Company's narrow-gauge industrial railway known as the "Yamasen" (Mountain Line). The original materials were retained, and its British-made double Warren truss structure is the only example of its kind remaining in Hokkaido. It is the oldest surviving active steel bridge in Hokkaido, holding considerable significance as an industrial heritage landmark.

The Yamasen served as a transport artery for timber, gold ore, and personnel, and was briefly open to general passengers before the line was closed in 1951. After closure, the bridge remained in place, and a three-year restoration project was completed in 1997 to address structural deterioration. The bridge was subsequently designated part of the "Modern Industrial Heritage Groups" by METI in 2007, and received the Civil Engineering Heritage Award from the Japan Society of Civil Engineers in 2018.

The bright vermilion bridge set quietly against the natural scenery of Lake Shikotsu makes for a striking and photogenic scene in every season, drawing visitors who want to capture its timeless image. It is one of the most rewarding stops during a visit to the Lake Shikotsu area.