NS Completes 1,000th DC-to-AC Locomotive Conversion

Published: March 16, 2026

In October 2025, Norfolk Southern Railway reached one of the most significant mechanical milestones in modern North American railroading, announcing completion of its 1,000th DC-to-AC locomotive conversion, the culmination of a decade-long fleet modernization program centered at the railroad’s historic Juniata Locomotive Shop in Altoona, Pennsylvania.

The landmark locomotive — AC44C6M No. 4947 — officially rolled out of Juniata during September and was publicly highlighted in early October 2025, symbolizing Norfolk Southern’s transition from one of the last major holdouts of DC-traction technology into an industry leader in rebuilt AC-powered freight locomotives.

The completion of No. 4947 carries symbolic importance beyond fleet statistics. The Juniata Shops — originally built by the Pennsylvania Railroad in the 19th century — have now helped usher in one of the most technologically advanced locomotive fleets in North America. From steam construction to diesel rebuilding and now high-efficiency AC modernization, Altoona once again stands at the center of railroad mechanical innovation.

Norfolk Southern AC44C6M #4822, painted in a tribute to NS workers, rolls eastbound 20X through Ambridge, Pennsylvania on July 27, 2024. Doug Kroll photo.

A Program That Reshaped Norfolk Southern’s Fleet

Norfolk Southern launched its DC-to-AC rebuilding initiative in 2015, targeting large fleets of aging GE Dash 9-44CW locomotives. Rather than purchasing thousands of costly new locomotives, the railroad chose a strategy focused on rebuilding existing assets into essentially new machines.

Under the program:

Locomotives are completely stripped to the frame
New cabs, electrical systems, and traction equipment are installed
AC traction technology replaces legacy DC systems
Units receive modern software, diagnostics, and fuel-management tools

Each rebuild requires approximately nine weeks to complete and extends locomotive service life by at least 20 years while costing roughly half as much as a new locomotive purchase.

Work has been shared between:

Norfolk Southern’s Juniata Shops
Former Roanoke Shops
Wabtec facilities in Erie, Pennsylvania, and Fort Worth, Texas

Why Convert from DC to AC?

During the 1990s and early 2000s, most North American railroads embraced AC traction for heavy freight service. Norfolk Southern, however, continued ordering DC locomotives longer than its peers.

By the 2010s, the advantages of AC traction were undeniable:

✅ Greater adhesion and pulling power
✅ Reduced wheel slip
✅ Lower maintenance requirements
✅ Improved fuel efficiency
✅ Better performance on coal, intermodal, and merchandise trains

Modernized locomotives are reported to be:

Up to 25% more fuel efficient
40% more reliable
Capable of delivering significantly greater tractive effort than their DC predecessors

Today, nearly 80% of Norfolk Southern’s road fleet operates with AC traction, largely due to this rebuild effort.

The AC44C6M

The overwhelming majority of conversions emerge as AC44C6M locomotives — now the backbone of Norfolk Southern’s mainline power fleet. These locomotives retain the proven Dash-9 platform while incorporating modern AC propulsion, digital control systems, distributed power capability, and Trip Optimizer energy-management software.

Specifications

Specification	Details
Model	GE AC44C6M
Rebuilt From	GE Dash 9-44CW
Power Type	Diesel-electric (AC traction)
Horsepower	4,400 hp
Prime Mover	GE 7FDL-16
Wheel Arrangement	C-C
Traction Motors	GE 5GEB13B7 (AC)
Starting Tractive Effort	~200,000 lbf
Continuous Tractive Effort	~180,000 lbf
Maximum Speed	75 mph
Weight	~432,000 lb
Fuel Capacity	4,600 gal
Build/Rebuild Period	2015–present

Inside the Conversion Process

At Juniata, the transformation is extensive enough that crews often describe the finished product as a new locomotive wearing an old frame.

Major rebuild steps include:

Removal of cab, engine components, wiring, and trucks
Structural inspection and frame renewal
Installation of new AC traction trucks
Addition of updated alternator and inverter systems
New crew and auxiliary cabs
Installation of onboard diagnostics and emissions improvements
Testing and repainting prior to release

The result is a locomotive that performs comparably to newly built power but with dramatically reduced capital expense.

Economic and Environmental Impact

The DC-to-AC program has become central to Norfolk Southern’s long-term operational strategy.

Key benefits include:

Lower lifecycle ownership costs
Reduced fuel consumption — one of railroading’s largest expenses
Fewer locomotive failures and shop cycles
Reduced emissions through efficiency gains
Standardized fleet components simplifying maintenance

The program also highlights railroading’s growing emphasis on asset circularity, repurposing existing equipment rather than replacing it outright.

Additional Units

Despite surpassing the 1,000-unit mark, Norfolk Southern’s modernization effort is not finished. Company officials indicated that roughly 190 Dash-9 locomotives remained candidates for conversion, meaning additional AC44C6M rebuilds are expected through the later 2020s. With the milestone achieved, Norfolk Southern has effectively transformed its locomotive roster — proving that rebuilding legacy power can rival new production in performance, sustainability, and cost efficiency.

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