Transformer fire near Tamachi halts Yamanote and Keihin-Tohoku lines

A fire in electrical equipment on the tracks near JR Tamachi Station has triggered a railway power outage and forced the suspension of service on the JR East Yamanote Line and the Keihin-Tohoku Line, snarling Tokyo’s morning commute and leaving thousands of passengers stranded.

Shortly before 8:00 a.m., a 119 emergency call reported flames on the tracks at Tamachi. Fire crews arriving on scene found a burned transformer in the track area, and the blaze was reported to be nearly extinguished about 30 minutes after it was first called in, according to the Tokyo Fire Department. Authorities say no injuries have been identified.

JR East halted trains on both lines in all directions and initially offered no timetable for resumption. Passengers were filmed disembarking from a Keihin-Tohoku train stranded between stations and walking along the tracks toward safety, assisted by firefighters and railway staff, footage shown by NTV. Social-media updates and live reporting from the scene documented heavy crowding at major transfer points as commuters sought alternate routes.

The disruption extended beyond the two lines that stopped. Service notices and operational updates indicated consequential delays on linked services, with the Tokaido Line expected to resume by 11:00 a.m. and operations on the Yamanote and Keihin-Tohoku lines expected to restart around 1:00 p.m. Some live updates cited knock-on delays on the Shonan-Shinjuku Line as passengers diverted across the network.

The scale of disruption is significant. The Yamanote Line circles central Tokyo and serves major interchanges including Shinjuku station, which handles roughly 3.5 million passengers a day at peak. The Keihin-Tohoku Line links central Tokyo with Yokohama and other southern hubs, meaning the outage affected both intra-city commuters and longer suburban flows. Anecdotal reports of increased pressure on buses, taxis, and other rail lines surfaced as commuters scrambled for alternatives.

The outage also prompted a market reaction. JR East shares fell about 3.6 percent in morning trading, the largest intraday drop for the stock since April of last year, reflecting investor concern about operational reliability and potential costs tied to service interruptions.

Investigators from the Tokyo Fire Department and JR East are examining whether the transformer fire caused the wider power failure or was a consequence of another electrical fault. Initial findings confirm flames and a burned transformer at the Tamachi trackside location and the suspension of service after the 119 call, but authorities say they have not concluded a definitive causal chain.

The incident highlights vulnerabilities in Tokyo’s densely interconnected rail grid, where a single trackside electrical fault can cascade across multiple high-capacity lines during peak travel. JR East is coordinating with emergency responders on recovery and has issued rolling operational updates to passengers.

Further reporting will need to quantify how many commuters were stranded, measure the full ripple effects on surface traffic and alternative transport, and track the outcome of the fire department and JR East investigation into equipment failures and response protocols. Regulatory scrutiny and potential demands for infrastructure upgrades are likely if investigators determine a preventable equipment failure or response shortfall contributed to the outage.