Tokyo Metro’s Tozai Line gets a new energy-saving drive system from December 2026
Tokyo Metro is preparing a major under-the-floor upgrade for part of its ageing Tozai Line 05-series fleet. The first trainset using a new synchronous-reluctance motor system and ultra-compact inverter is due to enter passenger service in December 2026, with nine trainsets planned by fiscal 2030.
The short version: this is a propulsion and power-electronics upgrade, not a timetable change. Tokyo Metro expects roughly 20–30% lower energy use than the equipment being replaced. The first upgraded 05-series set is planned for normal passenger service in December, and the programme is scheduled to expand to nine trainsets by FY2030.
What Tokyo Metro has announced
On 8 October, Tokyo Metro and Mitsubishi Electric announced that the Tozai Line’s 05-series will receive a new main-circuit package combining SynTRACS synchronous-reluctance motors with an ultra-compact VVVF inverter. The companies describe the combination as a world first for a railway main-circuit system.
The underlying motor technology is not starting from zero. Tokyo Metro and Mitsubishi previously tested SynTRACS on the Hibiya Line 13000 series, including long-term evaluation in commercial service. Tokyo Metro says that earlier system delivered about an 18% energy-saving effect compared with a conventional induction-motor system.
Why the Tozai Line version is different
For the 05-series renewal, Tokyo Metro expects a larger 20–30% energy-saving effect. The new motor is also about 9% lighter while delivering roughly 22% more output than the motor being replaced.
The inverter is the other major part of the story. Using silicon-carbide power devices and a higher-performance CPU, the new VVVF unit is about 81% smaller by volume and 43% lighter than the previous equipment. That matters on an existing train because under-floor space is already crowded: smaller equipment makes a retrofit easier without redesigning the whole vehicle.
When passengers will actually see it
Tokyo Metro says the first upgraded 05-series train is scheduled to begin commercial passenger operation in December 2026. By fiscal 2030, the plan is to have the system on nine trainsets.
This is not a replacement of every Tozai Line train at once. The 05 series will continue to operate alongside other Tozai Line rolling stock, so passengers may encounter an upgraded set without being able to choose it from the normal timetable. Tokyo Metro has not announced a separate passenger timetable, fare, stopping pattern or service-frequency change for the new equipment.
What riders may — and may not — notice
For most passengers, the immediate change is likely to be subtle. This is a traction-system renewal underneath the train rather than a new interior, new station or new route. The biggest gains are expected in energy efficiency, equipment weight, cooling demand and the practicality of extending the life of existing rolling stock.
There may be differences in traction sound or acceleration feel, but Tokyo Metro’s announcement does not promise a particular passenger-experience change. Treat claims about a quieter or faster ride as speculation until the upgraded train is actually in service and operating data are available.
The hardware in plain English
A synchronous-reluctance motor produces torque by exploiting differences in magnetic resistance inside the rotor. Compared with the induction motors commonly used on railways, the design can reduce rotor heat losses and improve efficiency.
For each 10-car trainset, the announced configuration uses 16 motors, each rated at 250 kW and weighing 551 kg, plus 16 inverter units weighing 140 kg each. The inverter controls the power supplied to the motors; shrinking and lightening that equipment is especially useful when fitting modern electronics into older train bodies.
Why this matters beyond one train
The Tozai Line is one of Tokyo’s busiest metro corridors, and fleet renewals happen over long cycles. If the projected energy savings are achieved in daily operation, the benefit repeats every time an upgraded train accelerates, cruises and brakes over years of service.
The bigger engineering point is that Tokyo Metro is trying to get more efficiency from existing 05-series vehicles rather than waiting for an entirely new fleet. A successful retrofit could give other operators another option when balancing energy reduction, equipment space and the cost of full rolling-stock replacement.
What to watch next
The key milestone is the first commercial run in December 2026. After that, the practical questions are whether Tokyo Metro confirms the expected energy savings in ordinary Tozai Line operation, how quickly the remaining eight planned trainsets are completed, and whether the same compact package is adopted elsewhere.
For travellers, there is nothing special to book or change today. Keep using the normal Tozai Line timetable and fare system; the upgraded train is a fleet-technology change rather than a new service product.