Union Pacific has signed a $1.2 billion agreement with Wabtec to modernize its fleet of AC4400 freight locomotives. The program will cover 1,700 units, representing about 24% of Union Pacific’s total locomotive fleet. The railroad aims to extend asset life while improving fleet performance and system reliability. The agreement ranks as the largest locomotive modernization contract in the rail industry.
Wabtec will complete the modernization work at its facilities in Erie, Pennsylvania, and Fort Worth, Texas. The companies executed the contract in the fourth quarter of 2025, continuing a modernization relationship that began in 2018. Each locomotive will receive an FDL Advantage engine upgrade, distributed power capability through LOCOTROL Expanded Architecture, and a modular control system supporting advanced diagnostics and software integration.
Union Pacific expects the upgraded locomotives to reduce fuel consumption by more than 5% and increase tractive effort by 14%. The railroad also anticipates an 80% improvement in reliability, supporting higher fleet availability and network efficiency. Production will begin after completion of Union Pacific’s prior modernization order, with deliveries scheduled to start in 2027. Once complete, the railroad will operate more than 1,700 modernized locomotives across its freight network.