Shuto Expressway Route 9 Fukagawa opens in full
On 5 February 1980 (Shōwa 55), the Hakozaki JCT–Tatsumi JCT section of Shuto Expressway Route 9 Fukagawa opened, completing the route, and the Tatsumi JCT–Shin-Kiba section of the Bayshore Route opened the same day.
According to Wikipedia, on this day the Hakozaki JCT–Tatsumi JCT section of Route 9 Fukagawa opened, completing the whole route, and the Bayshore Route's section from Tatsumi JCT to the Shin-Kiba ramps also opened. As the ward's description of the place name says, "the Shuto Expressway Route 9 passes through" Shiomi. Shiomi was thus linked by expressway ten years before it had a station.
Sources
Confirmed in Wikipedia text