Sekinosawa-Viadukt, Railway bridge in Shizuoka Prefecture, Japan

The Sekinosawa Viaduct is a steel railway bridge on the Oigawa Railway's Ikawa Line, between Omori and Kanzō stations, spanning the Sekinosawa River. Its 114.0 m length combines a two-hinged braced steel arch over the central 84.0 m span with plate girder approaches, and it stands 70.8 m above the riverbed.

The viaduct was completed in 1954 as part of an extension of the Oigawa Railway into the more remote mountain areas of Shizuoka Prefecture. Its construction opened up communities that had previously been largely cut off from the rest of the region.

The Oigawa Railway is known for running steam locomotives on a regular basis, and crossing this viaduct on one of those trains is a draw for visitors from across Japan. The sound of the steam engine echoing through the valley adds something to the journey that a diesel train simply does not offer.

The bridge is best experienced from a train on the Oigawa Railway, and open-air observation cars on certain routes give an unobstructed view of the span from above the valley. Those wanting a ground-level view can approach on trails in the valley below, though the terrain is uneven.

The Oigawa Railway is one of the very few lines in Japan that still operates a rack-and-pinion section, where a toothed rail helps trains grip the track on gradients too steep for ordinary wheels. This section sits further up the mountain line, beyond the viaduct, but passengers on the same journey cross both.