三條大橋, road bridge over the Shinano River in Sanjo, Japan

Sanjo Ohashi is a 463-meter steel box-girder bridge over the Shinano River in Sanjo, Niigata Prefecture, carrying National Route 8 on the Sanjo Bypass. It has four continuous spans on the north side and three on the south, with a total width of 26.3 meters, including sidewalks of 3 meters on both sides.

The first Sanjo Ohashi opened in 1964 as part of the Sanjo bypass, a two-lane bridge about 330 m long. Traffic growth and flood-capacity problems led to its replacement: work began in 1995, and on 4 December 2003 a four-lane bridge of 463 m opened. The old bridge had no sidewalks.

The bridge carries National Route 8 across the Shinano River on the Sanjo bypass, a four-lane crossing completed in 2003. Its name links it to the Sanjo district on the city's western side, and the structure is a steel continuous box girder bridge with a total length of 463 m.

Sanjo Ohashi carries National Route 8 (also Routes 17 and 403) across the Shinano River in western Sanjo; the bridge is 463 m long with 3 m sidewalks on both sides. Upstream stands the Joetsu Shinkansen's first Shinano River bridge, downstream the Zuium-bashi of Niigata Prefectural Route 1. The bridge has four lanes and no special pedestrian restrictions.

The first bridge opened in 1964 as a two-lane structure, but its embankment across the left-bank floodplain shortened the span and narrowed the waterway. The replacement, finished on 4 December 2003, lengthened the bridge from about 330 m to 463 m and enlarged the river cross-section by roughly 1.3 times.