In the early 2000s, Norfolk Southern, equipped with one of the largest fleets of GE DASH 9 series locomotives, found itself at a crossroads. With escalating traffic levels demanding more horsepower for efficient train movement, a critical decision loomed. The aging DASH 9s forming the backbone of their fleet were due for overhauls, prompting the need for a strategy to keep the traffic flowing seamlessly.
To modernize its fleet, Norfolk Southern boldly initiated a rebuilding program for its GE DASH 9s. This comprehensive process involved upgrading the electrical systems and traction motors of the aging DC (Direct Current) drives DASH 9s to AC (Alternating Current) traction, effectively transforming them into AC4400s. While AC technology had already proven effective on other railroads, Norfolk Southern remained conservative in the 90s, opting for fleets of DC-drive EMD SD70s, GE C40-9s, and C40-9Ws.
As the 90s transitioned into the 2000s, Norfolk Southern couldn't overlook the compelling advantages of AC, which offered significant improvements in unit tractive effort and overall train handling compared to DC units. The rebuild process also included essential enhancements such as new trucks, repairs to the carbody, and additional ballast for increased tractive effort.
Externally, the most noticeable change was the addition of an AC inverter control cabinet to the left side walkway behind the operator’s cab. In the case of units rebuilt from standard-cab C40-9 core units, the original operator’s cab, low nose, and under-cab cabinets were replaced with a new GE Safety Cab, similar to those used on current GEVO production. While some fans lamented the loss of the distinctive C40-9 "Top Hats," crews embraced the new cabs for their superior comfort and crashworthiness.
These revitalized units, designated as AC44C6M by Norfolk Southern, made their debut in August 2015 with NS 4000 and 4001, rebuilt by contractor American Motive Power, Inc., utilizing components from GE. Sporting a unique gray scheme with a blue cab and "mane," these units stood out against the typical black Thoroughbreds in the NS fleet. Rebuilt from NS C40-9s 8799 and 8879, some of the oldest GEs in the fleet gained a new lease on life.
The success of these initial rebuilds prompted Norfolk Southern to fully embrace the AC44C6M, with 16 additional units rebuilt from C40-9 cores in 2016. Work was conducted both in-house at Roanoke and Juniata shops and by GE at their facilities in Erie, Pennsylvania, and Ft. Worth, Texas. The momentum continued, with additional units slated for rebuilding each year. At present, the plan is for Wabtec to rebuild the entire NS GE DASH 9 fleet, ushering in the latest technology and solidifying its position as the "Thoroughbred" of transportation.
