On "Hitotsubashi" over the Nihonbashi River north of Palaceside Building in Takebashi, Tokyo, seismic work is scheduled through March 29. Visible so far is mainly signage; full anti-collapse reinforcement under the bridge with scaffolding comes next.
"Hitotsubashi," which gave the district its name, is said to derive from a single log bridge when Tokugawa Ieyasu entered Edo Castle. Tokugawa Yoshimune's son Munetada received a residence here and took the name "Hitotsubashi family" after this bridge.
The present bridge was completed in Taisho 14 (1925) as part of Great Kanto Earthquake recovery. Arch sections on both sides are abutments; the center is a steel girder bridge with "bridge lamps" atop end posts—a rare type today.
Eighty-seven years since completion. As part of Tokyo's seismic plan, the construction bureau says: "As is, in a magnitude-7 quake the bridge might fall—but after completion, 'It won't fall even in magnitude 7.'"