The bridge system includes the world's longest two-tiered bridge structure, spanning 13.1 kilometers total.
Construction required a decade of work, starting in 1978 and finishing in 1988.
The project features a mix of six distinct bridge types, including suspension, cable-stayed, and truss designs.
It was designed to withstand significant seismic activity, a necessity in the geologically active Japanese archipelago.
The bridge deck construction utilizes a dual-level system to separate heavy railway traffic from automobile expressway lanes.
It crosses five small islands in the Seto Inland Sea, utilizing them as anchor points for the bridge piers.
The total amount of steel used in the project exceeds 700,000 tons.
The Seto Ohashi Bridge is a multi-level double-deck suspension and truss bridge system spanning the Seto Inland Sea, connecting Okayama Prefecture on Honshu to Kagawa Prefecture on Shikoku. Completed in 1988, it consists of six bridges and four viaducts stretching over 13 kilometers, making it one of the longest two-tiered bridge systems in the world. The structure carries both the JR Seto-Ohashi Line railway on the lower deck and a four-lane expressway on the upper deck. It serves as a vital transportation artery across the islands of the Seto Inland Sea. The engineering design integrates suspension, cable-stayed, and truss bridges to accommodate the region's varying water depths and island geography. It remains fully operational and is managed by the Honshu-Shikoku Bridge Expressway Company.
The shoreline promenade within the Seto Ohashi Memorial Park in Sakaide.
Visit the Seto Ohashi Memorial Park at the Sakaide end for the best ground-level perspective.
Use the observation deck at the Seto Ohashi Memorial Museum to view the bridge structure without obstructions.
Monitor local wind conditions, as the bridge expressway can implement speed restrictions or closures during extreme weather.
Attempting to photograph the bridge from the highway lanes, as stopping on the expressway is strictly prohibited.
The bridge remains open 24/7, though expressway lanes may occasionally close for maintenance or during severe typhoon conditions.
