Bertolotti completed the first of eight battery shunting locomotives ordered by Milano metro operator ATM in early September, and the vehicle went on display at InnoTrans 2026. The Italian manufacturer disclosed the completion date to Railway Gazette International at the Berlin trade fair, where the machine stood as the public reference point for a traction programme that now spans three operators.

The numbers behind the display matter more than the stand itself. The e² Formula carries a continuous power rating of 1 MW and can haul trains of up to 2 900 tonnes at speeds of up to 30 km/h — enough tractive capability, on paper, to recover a failed metro set on gradient and move rolling stock across a depot throat without a catenary connection.

Who supplies what?

ABB supplies the critical electrical chain. The Swiss-Swedish group provides the lithium titanate oxide battery pack, the traction converter and the traction motor. Lithium titanate chemistry trades energy density against fast charging and long cycle life, a compromise that suits shunting duty cycles, where locomotives work in short bursts and return to a charge point between shifts, rather than sustained mainline running.

The locomotive is fitted with automated couplers and standard UIC/FS drawgear. That dual equipment allows the same machine to couple with metro stock and with conventional rail vehicles — a practical requirement for rescue operations, where the shunter may have to attach to a disabled train of either configuration.

How large is the order book?

The ATM fleet is one of three e² Formula commitments Bertolotti has in hand.

• Eight locomotives for ATM, the Milano metro operator, for shunting and rescue duties. The first was finished in early September; the manufacturer did not state a delivery schedule for the remaining seven.
• Eight locomotives for EAV, the Napoli regional operator, under a €24.4m contract confirmed in July 2026 — roughly €3m per unit, a useful yardstick for what battery shunting traction of this class costs in the current market.
• Two locomotives for RTM, the Marseille metro operator, under an agreement finalised in June, with an option for a third.

Eighteen firm units across three cities, plus one option, is a modest but geographically diverse book for a specialist builder. Notably, two of the three customers are metro operators, suggesting the battery shunter's economics currently clear the investment hurdle in depot environments — where distances are short, ventilation is a cost factor and diesel exhaust is unwelcome — more readily than on open freight yards.

What is not being said?

The InnoTrans presentation answers fewer questions than it raises. Bertolotti gave no charging time, no battery capacity in kilowatt-hours and no expected range between charges — the three figures an operator needs to judge whether a 1 MW rating translates into usable working hours. The chemistry choice implies fast charging is part of the design case, but the manufacturer has not published the figures to verify that.

ATM has not said when the eight locomotives will enter service, nor which depots they will work. The completion of the first unit in early September demonstrates that the build programme is real and moving; it does not yet demonstrate fleet-level reliability, which only months of depot operation can establish.

The €24.4m EAV contract price provides the only public cost signal, and it covers a separate order that may differ in specification from the ATM machines. Any comparison across the three contracts remains an estimate until the Marseille and Milano values surface.

Does 2 900 tonnes hold up?

The headline tractive claim deserves scrutiny of a different kind. Moving 2 900 tonnes at 30 km/h on flat, straight depot track is a modest duty for a 1 MW locomotive; the same mass on a gradient or through tight curves, where metro rescue work actually happens, demands more of the traction system and the adhesion available. Bertolotti did not publish gradient-specific performance, so the figure should be read as a level-track rating rather than a guarantee for every recovery scenario ATM might face.

The automated couplers narrow that risk in one respect: faster, safer coupling during a recovery reduces the time a failed train blocks the line, whatever the load being hauled.

What comes next?

With the first ATM unit complete and the EAV build running in parallel to a July 2026 contract confirmation, the next verifiable milestone will be entry into regular depot service in Milano — the point at which charging behaviour, availability and rescue performance can be measured rather than promised.