Hakozaki Junction

The most structurally complex junction on the Shuto Expressway, where the Inner Circular Route (C1), Route 6 (Mukojima Line), and Route 9 (Fukagawa Line) converge in Nihonbashi Hakozaki-cho, Chuo City. A right-turn rotary embedded within a four-tier elevated structure earned it the nickname 'King of Junctions'.

Three Routes, One Complex Node

In Nihonbashi Hakozaki-cho, Chuo City — where elevated expressway ramps fill the sky above the Sumida River — stands the junction the road-enthusiast community has dubbed the “King of Junctions.” The Inner Circular Route (C1), Route 6 (Mukojima Line), and Route 9 (Fukagawa Line) converge at a single point, making Hakozaki Junction both a vital hub in the Shuto Expressway network and one of its most notorious congestion spots.

Route 6 reached this location when the Edo-bashi Junction to Mukojima stretch opened on 21 March 1971. The junction took its decisive form on 5 February 1980, when Route 9 (Fukagawa Line) opened alongside the junction itself. The addition of Route 9 — the primary connection between central Tokyo and the bay area — transformed what had been a straightforward interchange into a three-route convergence. Engineers who built it called it “bakemono inter” (the monster interchange) from the outset, and the nickname has stuck.

The Rotary Inside a Motorway

Hakozaki Junction’s most distinctive feature is the Hakozaki Rotary, embedded in the lower levels of a structure that reaches four tiers when ordinary roads are included. The rotary runs one way clockwise, enabling vehicles to transfer between Route 6 and Route 9 via a loop that no conventional junction layout can replicate. Inside the rotary, a small rest area — Hakozaki Parking Area — provided a stop for long-distance drivers.

Equally unusual was the presence of traffic signals within the expressway itself. Installed to regulate merging flows, they operated for more than forty years before being removed in 2025. A major improvement programme carried out between 1994 and 1998 added a dedicated left-branch from the C1 inner loop to Route 9, easing the weave-merging congestion that had long made the junction a notorious bottleneck.

Summary

Hakozaki Junction took its present form on 5 February 1980, when Route 9 (Fukagawa Line) opened and the Inner Circular Route, Route 6, and Route 9 became fully interconnected in Nihonbashi Hakozaki-cho, Chuo City. Its four-tier structure and embedded rotary make it unlike any other junction on the Shuto network; the crossing ramps visible from street level remain a monument to the ambition — and the improvisation — behind Tokyo’s expressway system. A walk along the Sumida riverbank towards Hamachō offers a view of the stacked ramps that conveys the scale far better than any photograph.

Related: Inner Circular Route (C1) / Bayshore Route

Staying in central Tokyo? Rakuten Travel has hotels across Chuo City and Nihonbashi.