Tokyo Bay Aqua-Line

The Tokyo Bay Aqua-Line spans 15.1 kilometers across Tokyo Bay, connecting Kawasaki with Kisarazu through a combination of undersea tunnel and bridge sections.

Construction of this transportation link began in 1986, with engineers developing advanced tunneling techniques to overcome the challenges of soft seabed and deep water conditions.

The Umihotaru rest area, positioned at the junction between tunnel and bridge sections, functions as a maritime observation point for Tokyo Bay marine activities.

The expressway reduces travel time between Kawasaki and Kisarazu from 90 minutes to 30 minutes, offering four traffic lanes with potential expansion to six lanes.

The tunnel section extends 60 meters below sea level and required the use of shield machines with a 14-meter diameter to excavate through complex geological formations.

Location: Kawasaki-ku

Location: Kisarazu

Inception: October 1, 1986

Official opening: December 18, 1997

Width: 22.9 m

Part of: 3環状9放射, Japan National Route 409

Website: https://umihotaru.com/company

GPS coordinates: 35.46306,139.87528

Latest update: September 23, 2025 16:53