Wabtec modernisation agreement to rebuild Union Pacific AC4400s

Union Pacific has signed the Wabtec modernisation agreement to upgrade its AC4400 locomotives under a $1.2 billion contract, as outlined by Union Pacific.

Described as the rail industry’s largest locomotive modernisation investment, the deal builds on Union Pacific’s 2022 order, which is set for completion in 2026.

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Once the upgraded fleet is delivered, the railroad expects gains in operational efficiency alongside improved service reliability and network performance. Union Pacific CEO Jim Vena said the company remains focused on delivering the service it sold to customers, and that American-made locomotives are part of that effort.

He added that the redesigned units are expected to be “like new,” bringing improved fuel efficiency and enhanced reliability to support growth with current customers and help win new business.

AC4400 locomotive upgrade program targets

Wabtec says the modernisation programme will extend the lifespan of each locomotive, improve fleet standardisation and help Union Pacific take advantage of next-generation control and diagnostics technologies. Each upgraded locomotive is expected to deliver more than a 5% reduction in overall fuel consumption, a 14% increase in tractive effort and an 80% improvement in reliability, according to Wabtec’s press release.

Wabtec hardware and digital technologies package

Wabtec President and CEO Rafael Santana described the partnership as a steady, forward-looking investment for Union Pacific and its customers. He said the program enhances proven locomotive platforms with advanced propulsion, controls and diagnostics, delivering gains in performance, reliability and lifecycle value, while allowing the railroad to unlock more efficiency and capability from its existing fleet.

Under the agreement, the locomotives will be equipped with a suite of Wabtec hardware and digital technologies. Each unit will receive the FDL Advantage (FDLA) engine upgrade aimed at additional fuel savings, LOCOTROL® Expanded Architecture to support safe, efficient operation of longer trains, and the new Modular Control Architecture, enabling next-generation data, diagnostics and software capabilities.

Fleet scale, timeline and deliveries

Signed in the fourth quarter of 2025, the contract is Union Pacific’s fourth major modernisation order from Wabtec since 2018. Once completed, Union Pacific is expected to have more than 1,700 modernised locomotives available. All production will be handled at Wabtec’s US facilities, with deliveries set to begin sometime in 2027, as reported by Railway Gazette.

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