The BL2: EMD's Ugly Duckling?
The Cab Unit-Road Switcher Hybrid

EMD BL2 Diagram

The BL2 occupies an interesting place in diesel locomotive history. Not quite a cab unit, but also not quite a road switcher, this short-lived offering from EMD set the stage for the enormously successful GP7 that would put an end to the cab unit era. Although the cab unit had been embraced by the railroads, there were several factors in their design that limited their usefulness. With no platforms and walkways on the exterior for crews to use, cab units were not well suited for switching duties. Access to components was also quite limited. In addition, the car bodies in cab units were an integral part of the structural integrity of the unit, further complicating maintenance. What the railroads needed was a more versatile locomotive, with platforms for better visibility when switching, and easier access for major repairs. The eventual result would be the road switcher, but not before EMD produced the BL2-a transitional locomotive that served as a test-bed for the latter road switchers.

The BL2 was introduced to counter the highly-successful RS-1 and RS-2 produced by Alco. The BL stood for "branch line", meaning that these locomotives would be used on lines with light traffic and tight limits on axle loadings. The BL2 would be called upon to pull light freight trains, occasional passenger trains, and perform switching duties. To design this locomotive, EMD essentially modified a F3 cab unit into a road switcher by adding front and read platforms, narrow the hood so the crew in the cab can see the person on the front "porch", and attempting to make the unit visually attractive for possible passenger service. This was a tall order that was not completely achieved. Nevertheless, the BL2 found a home on several large railroads, laying the foundation for the road switcher boom that followed.

BL2 Technical Data:

Model: BL2
Horsepower: 1500
Engine: 567B
16 cylinders
Produced: 1948-49
Units sold: 59 (1 BL1 and 58 BL2s)
Horsepower: 2250

Technical Features:

1. The BL2 produced 56,200 lbs. of tractive effort with a dry weight of just over 210,000 pounds.
2. The BL2 could carry 1,100 gallons of fuel oil, 200 gallons of lube oil, 204 gallons of cooling water, and 16 cubic feet of sand.
3. Although not originally intended for multiple-unit operation, most BL2s were modified for this type of service. They could also be equipped with dual controls for bi-directional capability.
4. The BL2 was available with an optional steam boiler for passenger service, the tank could hole 625 gallons of water for the boiler.
5. Weakness of the frames in the BL2 limited their usefulness in multiple-unit operation to no more than 2 units at one time.


1. Access to major components in the BL2 was difficult, no better than a cab unit, and this reduced the appeal of the BL2 to the railroads. The introduction of the GP7 model in late 1949 by EMD sealed the fate of the BL2.
2. The first BL2 was designated a BL1, with an air-actuated throttle. However, while this type of throttle was good for switching, it would not allow MU operation. EMD therefore modified the throttle design in the BL1 demonstrator and redesignated the model BL2.
3. The BL2 was not a successful model for EMD, with only 59 produced. Bangor and Aroostook, Boston and Maine, Chicago and Eastern Illinois, C&O, FEC, MP, Monon, Rock Island, and Western Maryland purchased the BL2.
4. The frame weakness of the BL2, when combined with MU operation, had serious consequences for the model. Maintenance costs were higher than on the new GP series, and the lifespan of the BL2 was reduced by this structural problem.

Historical Analysis:

The BL2 is something of an oddity in the history of diesel locomotives. It was a rare miss by EMD, the monolith of diesel builders in those days. However, the BL2 allowed EMD to test technologies for the road switcher design that would soon follow. EMD learned what to do, and not what to do, in the design of the GP7. Many features of the BL2 were used in the GP series. And the BL2 did perform useful service for several railroads for many years, indicating the basic design was not seriously flawed. The BL2 will likely be remembered as a transitional locomotive that set the stage for the next revolution in diesel locomotive design.

Railfan Perspective:

The BL2 seems to have a polarizing effect on railfans, they are either loved or hated. Many call them "ugly ducklings". However, they are unique locomotives, with an interesting history. They are unlike anything else, and very easy to recognize. They look like a cross between an F unit and a GP7. The result of this is that they are neither beautiful nor ugly, in this writers opinion. The BL2 was merely an (un-intended) experimental locomotive that was a unique sight on the rails that were dominated by cab units and, later, road switchers. Railfans can be glad that this distinctive model was produced, since variety of motive power is important to a railfan.


I know of 7 surviving BL2s, including Monon #32 at the Kentucky Railway Museum in New Haven. The other units originally belonged to BAR and WM. (I will add more later as the info is available)

Photo by Daniel Dawdy.


 "The American Diesel Locomotive" Brian Soloman. MBI Publishing. 2000.

 "Modern Diesel Locomotives" Hans Halberstadt. MBI Publishing. 1996

"Vintage Diesel Locomotives" Mike Schafer. MBI Publishing. 1998

"A Field Guide to Trains" Gerald Foster. Houghton-Mifflin. 1996

 "Diesel Locomotives: The First 50 Years" Louis A. Marre. Kalmback Books. 1995
 "C&O BL2 Diesels" John C. Paton. C&O Historical Society. 1991

 "The Encyclopedia of Trains and Locomotives" C.J. Riley. MetroBooks. 1995

"EMD's BL2". Diesel Data Series, Book 3. Hundman Publishing.

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