Union Pacific, Wabtec Ink $1.2B Deal To Modernize AC4400 Fleet

Published: February 16, 2026

OMAHA / PITTSBURGH — Feb. 2026 — Union Pacific has signed a $1.2 billion agreement with Wabtec to modernize a significant portion of its GE AC4400 fleet, doubling down on the strategy of rebuilding proven high-horsepower road units rather than replacing them outright. Announced February 4, 2026, the deal is being billed by the companies as the largest locomotive modernization investment in rail industry history and is expected to produce measurable improvements in fuel efficiency, pulling performance, and day-to-day reliability.

Union Pacific AC4400CW #6758, then nearly new, leads Powder River Basin coal at Logan, Wyoming in October, 1996. Warren Calloway photo.

What Union Pacific is buying—and why it matters

Under the agreement, Wabtec will deliver a package of hardware, controls, and digital upgrades intended to make UP’s AC4400s perform “like new,” extending useful life while standardizing systems across a modernized fleet. Union Pacific CEO Jim Vena framed the purchase as a service-driven investment: a more dependable locomotive fleet supports the railroad’s ability to deliver the service it has committed to customers—and to compete for new business.

Wabtec’s CEO Rafael Santana emphasized the lifecycle math behind rebuild programs: modernizing existing platforms with updated propulsion, controls, and diagnostics can unlock meaningful performance gains while maximizing return on assets the railroad already owns.

The upgrade package: engines, distributed power, and next-gen controls

While the companies did not publicly break out unit counts, they did outline the core technology suite going into each locomotive. According to the joint announcement, each modernized AC4400 will receive:

FDL Advantage (FDLA) engine upgrade, aimed at improving fuel efficiency and extending the life of the GE 7FDL prime mover platform in UP’s legacy fleet.
LOCOTROL® Expanded Architecture, Wabtec’s distributed power (DP) platform, designed to support the safe and efficient operation of longer trains by better coordinating power throughout the consist.
Modular Control Architecture, described as a foundation for next-generation onboard data, diagnostics, and software—essentially turning these legacy locomotives into more digitally enabled assets that can be monitored, tuned, and troubleshot with far greater precision.

Taken together, the companies project the modernized locomotives will deliver more than a 5% reduction in fuel consumption, a 14% increase in tractive effort, and an 80% improvement in reliability—a trio of metrics that directly translate into fewer failures on the road, fewer recrews, less rescue power, and more consistent velocity through UP’s network.

Timing and scope: Deliveries begin in 2027

The agreement was signed in the fourth quarter of 2025, with production at Wabtec’s U.S. facilities and deliveries beginning in 2027, according to the companies.

A key headline figure is what the deal implies about Union Pacific’s total rebuild program. Once this order is completed, UP says it will have more than 1,700 modernized locomotives in its fleet—an enormous slice of road power that will share more common systems, diagnostics, and operating characteristics.

Notably, UP has not confirmed the exact number of AC4400s included in this latest modernization tranche. Railway Age reported that, based on previously disclosed totals and the “more than 1,700” figure, the publication estimates the latest order could be roughly 670 units, though that remains an informed estimate rather than a stated number from the railroad.

The AC4400: a workhorse platform built for heavy freight

Union Pacific’s target fleet, the GE AC4400CW, is among the most successful AC-traction freight locomotive designs of the modern era. The model—rated at 4,400 horsepower and built in large numbers beginning in the 1990s (UP's first began arriving in October and November, 1995)—brought AC traction’s high-adhesion advantages into widespread North American service, making it well-suited for heavy tonnage and mountain grades.

For UP, the AC4400s represent a deep pool of proven frames, trucks, and electrical systems that can justify a second (or third) life when paired with modern controls and efficiency upgrades. Modernization also offers a practical path to improving performance while managing capital spending: rebuilding is often faster to scale than acquiring entirely new fleets, and it can reduce complexity by standardizing systems across multiple legacy sub-fleets.

Building on earlier orders: UP’s long-running modernization pipeline

This isn’t UP’s first major commitment to rebuild programs with Wabtec. The companies say the 2026 agreement is Union Pacific’s fourth major modernization order since 2018.

The most directly comparable milestone is UP’s 2022 modernization order, which Railway Age described as a program to upgrade 600 locomotives—including 525 AC4400s and AC6000s, plus 75 Dash 9 units—with work scheduled to be completed in 2026.

That timeline matters because it suggests a “rolling pipeline” strategy: as one tranche nears completion, the next tranche is contracted, allowing UP and Wabtec to keep facilities, labor, and supply chains aligned around predictable rebuild volumes.

Why rebuilds are surging across the Class I landscape

Beyond UP’s internal fleet strategy, the timing of the announcement reflects a broader industry trend: North American railroads are actively upgrading and replenishing fleets with more efficient, digitally enabled power. Reuters noted that U.S. rail operators have been ramping up fleet modernization, supported by broader infrastructure investment dynamics, as they seek to replace or refresh aging locomotives with models that deliver better fuel economy and performance.

From an operating standpoint, the promised gains—fuel burn, tractive effort, and reliability—hit three of a railroad’s most important levers at once:

Fuel remains one of the biggest variable costs in railroading. A fleet-level fuel efficiency gain of “5%+” becomes substantial when applied to hundreds of high-utilization road units.
Tractive effort supports heavier trains and more consistent handling, which can reduce the need for additional helper power and improve throughput on key corridors.
Reliability reduces unplanned downtime and the cascading network impacts of failed power—often the hidden cost that hurts velocity, crews, and customer confidence.

Where the work happens

Wabtec states production will occur at its U.S. facilities. While the companies didn’t list specific shops in the press releases, Trains noted UP locomotives undergoing modernization at Wabtec’s facility in Fort Worth, Texas, underscoring the domestic footprint behind the “American-made” message highlighted by UP leadership.

What to watch next

The two biggest open questions are unit count and cadence—how many AC4400s are included, and how quickly Wabtec can push modernized units out the door beginning in 2027. If UP ultimately modernizes something close to the estimated figure suggested by Railway Age, the project would represent one of the most significant single-platform refreshes ever undertaken by a U.S. freight railroad.

For now, the key takeaway is clear: Union Pacific is betting that modern electronics, upgraded engines, advanced distributed power architecture, and richer diagnostics can turn late-20th-century horsepower into a 21st-century fleet—delivering measurable operating gains without waiting for the long lead times (and higher price tags) of brand-new builds.