Alco "RS-3" Locomotives

Last revised: June 7, 2023

By: Adam Burns

The Alco RS3 was the builder's pinnacle in its early road switcher designs. While the American Locomotive Company would have some success in later Road Switcher (RS) series models, like the RS11 and RSD5, nothing would compare to the amazing success of the RS3. 

When it was released Alco had already cataloged two previous versions, the RS1 and RS2, both of which had seen modest success as the first true road-switchers ever produced.


Unfortunately, overall the Schenectady manufacturer had considerable trouble seriously competing with Electro-Motive whose cab designs were far outpacing anything in its catalog.

In any event, the RS3 would go on to be the most commonly seen Alco model across the country and remained in the company's catalog for more than six years. Today, numerous examples of this locomotive remain preserved, several of which are still operational.


78900192375541434152177482895607098.jpgRock Island RS3s #486 and #494 work an outbound suburban run from Chicago's LaSalle Street Station, circa 1967. collection.

The Alco RS3 entered production in 1950 replacing its predecessor the RS2. The new model produced slightly more horsepower than the earlier design at 1,600 hp using Alco's commonly problematic 12-cylinder, model 244 prime mover. 

From a visual standpoint the RS3 looked almost identical to the RS2. Both had much improved styling over the RS1 albeit it was quite subtle with heavy beveling to corners and edges giving the unit a much more streamlined appearance (because of its good looks some railroads elected to employ theirs in passenger/commuter service). 

Instantly beloved by railroads for its versatility and reliability, RS3s began rolling out of Alco's Schenectady shops in the masses.

Missouri Pacific RS3 #982 and GP7 #236 are tied down in Lee's Summit, Missouri during September of 1964. collection.

Perhaps more than any other locomotive the RS3 defined Alco as a locomotive manufacturer offering eye-appealing, classy designs with their trademark belching black smoke.  

While the RS1 and RS2 had sold relatively well perhaps it was the RS3's extra 100 horsepower over its predecessor that really appealed to railroads. 

While the model 244 proved generally reliable and rugged in its smaller switcher and light road switcher designs (like the RS3) the prime mover simply not been properly researched and developed for heavy-haul use. 

As such, the FA and PA models in production at the time experienced significant mechanical issues.  This allowed Electro-Motive to gain a notable edge and these problems ultimately resulted in Alco's exit from the market.

Erie Lackawanna RS3 #1044, a former Lackawanna unit (#906), is seen here in the early 1960s. collection.

Interestingly, a year prior to the RS3's release EMD was finally cataloging a competitor, the GP7. Unfortunately for EMD their initial design, the BL2, proved unsuccessful although the industry leader quickly learned from their mistake.

The model used the same road switcher design setup pioneered by Alco in its 1941 RS1 with a long trailing hood, offset cab, and short front hood.   Both as the time as well as from a historical stance the RS3 has been deemed an incredible success for Alco.

However, had the builder acquired the reputation of EMD it may have sold even more.  The GP7 went on to sell more than 2,700 examples before its production run ended in 1954 and its successor, the GP9, was even more successful.

36930945672358296329889379890.jpgPennsylvania RS3 #5456 between assignments in Cincinnati, Ohio during the summer of 1967. Fred Byerly photo. collection.

When the RS3 was produced Alco was still working in conjunction with General Electric and Westinghouse to supply internal components for its locomotives.

As such the model contained air brakes and compressors from the latter while the former provided its model 752 traction motors that gave the RS3 around 60,000 pounds of initial tractive effort (more than 2,000 more than the RS2).

The model weighed around 114.5 tons, was 55 feet/5 inches in length and equipped with dynamic braking. This latter ability allowed railroads to use the RS3 in heavy-haul service, such as moving coal drags up steep grades and many did not shy away from doing so; for instance the Reading, Lehigh Valley, Louisville & Nashville, Southern and others beat theirs to pieces in this capacity.

Canadian Pacific RS3 #8441. Date and location not recorded. collection.


It was the model's ability to take this abuse regularly and continue operating on a daily basis that so endeared them to railroads and resulted in many returning to Alco for more.  

It's a shame that the company could not have produced other locomotives that emulated the success of the RS3. By the time production ended in 1956 Alco would sell more than 1,300 and even today you can still find these venerable locomotives operating on short lines and tourist trains all across the country.

Most interesting is that when Alco introduced its RS line in 1941 and found success with a locomotive that could be used in multiple roles EMD was convinced to begin manufacturing its own line of road switcher that would eventually help put Alco out of business one day.  

Data Sheet and Specifications

Alco Class404-DL-247
Entered Production5/16/1950 (Great Northern #198)
Years Produced5/16/1950-8/1956
Model SpecificationE1662/A/B: MLW = ME1600R
Engine244, V-12
Carbody StylingAlco
Length (Between Coupler Pulling Faces)56' 6"
Weight247,000 Lbs. (Optional ballasting to 250,000 Lbs.)
Dynamic BrakesOptional
Truck TypeSwing Bolster, Drop-Side Equalizer (AAR Type-B)
Truck Wheelbase9' 4"
Wheel Size40"
Traction MotorsGE 752 (4)
Traction GeneratorGT581
Steam GeneratorOptional
Gear Ratio74:18
Tractive Effort Rating42,500 Lbs. at 11 MPH
Top Speed65 MPH

Production Rosters


Owner Road Number(s) Quantity Date Built
Alco Demonstrator1600-1601, 160731950, 1952
Alton & Southern43-4531950-1956
American Smelting & Refining2-321950
Atlantic & Danville10711951
Birmingham Southern151-15221950-1951
Blue Ridge Railway1-221950
Boston & Maine1505-1519, 1535-1545261952-1954
Carolina & North-Western5, 1021950, 1953
Central Of Georgia108-119, 133-159391950-1953
Central Railroad Of New Jersey1540-1555, 1700-1709261950-1953
Central Vermont1859-186021954
Chesapeake & Ohio5600-560121955
Chicago & North Western1551-1555, 1613-1624171951-1953
Cincinnati, New Orleans & Texas Pacific (Southern)6208-6239321952
Chicago, St. Paul, Minneapolis & Omaha (C&NW)162-16761952-1953
Danville & Western1-221950
Delaware & Hudson4026-41291041950-1953
Delaware, Lackawanna & Western (Lackawanna)901-918181950-1952
Denver & Rio Grande Western5200-520451951
Erie914-933, 1005-1038541950-1952
Federal Barge Lines60-6121952, 1955
Grand Trunk Western1861-186221954
Great Northern197-199, 220-224, 228-232131950-1953
Green Bay & Western305-30841951, 1955
Gulf, Mobile & Ohio1515-152391950-1952
Interstate Railroad30-36, 38-3981953, 1956
Kennecott Copper10911950
Lake Superior & Ishpeming1604-161071950-1955
Lehigh & Hudson River1-13131950-1951
Lehigh Valley215-21621950
Litchfield & Madison301-30331952-1956
Long Island Rail Road1551-1560101955
Louisville & Nashville100-154, 170-179, 214-2551071951-1956
Macon, Dublin & Savannah1703-170641950-1956
Maine Central556-55721953
Milwaukee Road2475-2495211953-1955
Minnesota Transfer200-20121951
Missouri-Illinois Railway19-20, 62-74151951-1955
Missouri-Kansas-Texas (Katy)1551-1563, 1701-1702151950-1951
Missouri Pacific4501-4526261955
New Haven517-561451950-1952
New Orleans & Northeastern (Southern)6875-688281950
New York Central8223-83521301950-1953
Nickel Plate Road535-557231954
Norfolk & Western300-30781955-1956
Northern Pacific850-863141953-1955
Oliver Iron Mining1108-111031950
Pennsylvania8435-8484, 8590-8605, 8817-8856, 8902-89161211951-1955
Piedmont & Northern100-109101950-1951
Pittsburgh & Lake Erie (NYC)8353-835751953
Reading444-475, 481-524761951-1953
Rock Island455-474, 485-499251950-1951
Soo Line352-35321954
St. Louis Southwestern (Cotton Belt)308-310, 311 (1st/2nd), 312-318, 356-360171951-1952
St. Marys Railroad501-50221951, 1956
San Manuel Copper1-331955
Seaboard Air Line1629-1684561950-1952
Southern2025-2062, 2131-2145531951-1953
Spokane, Portland & Seattle65-82, 90-98271950-1955
Tennessee Central251-260101950-1956
Terminal Railroad Association of St. Louis (TRRA)1600-160341950
Texas Pacific-Missouri Pacific Terminal2411956
Toledo, Peoria & Western20711950
Western Maryland185-198141953-1954
Yadkin Railroad911951

Montreal Locomotive Works

Owner Road Number(s) Construction Number Completion Date
Quebec, North Shore & Labrador Railway102-10376110-761117/1951
Ontario Northland1304-130776112-7611510/1951
Ontario Northland1308-131176727-7673011/1951-12/1951
Central of Brazil3301-334877650-7769710/1952-8/1953
Pacific Great Eastern569-57179121-791237/1953-8/1953
Pacific Great Eastern572810127/1954
Pacific Great Eastern573-57581172-8117411/1954-12/1954
Pacific Great Eastern576-57881204-812065/1955
Canadian National7830-783479124-7912811/1953-8/1953
Canadian National7835-784779180-7919211/1953-12/1953
Canadian National1818-184081013-810358/1954-10/1954
Canadian Pacific8426-844680991-810113/1954-6/1954
Canadian Pacific8447-846181036-8105011/1954-12/1954
Roberval & Saguenay22811854/1955


  • Foster, Gerald. A Field Guide To Trains. New York: Houghton Mifflin, 1996.
  • Kirkland, John F. Diesel Builders, The:  Volume Two, American Locomotive Company And Montreal Locomotive Works. Glendale: Interurban Press, 1989.
  • Pinkepank, Jerry A. Diesel Spotter's Guide.  Milwaukee: Kalmbach Publishing Company, 1967.
  • Solomon, Brian. Alco Locomotives. Minneapolis: Voyageur Press, 2009.

89239427652y970029287289932907.jpgIn a photo taken from the 4th Street footbridge, Pennsylvania Railroad RS3 #8906 switches a cut of cars near the locomotive shops in Altoona, Pennsylvania on May 5, 1960. David R. Sweetland photo. collection.

Of note, Alco's Canadian arm, the Montreal Locomotive Works, was not nearly as successful with the RS3 selling just 98 to the Canadian National, Canadian Pacific, Ontario Northland, Pacific Great Eastern, Quebec, North Shore & Labrador, and the Roberval & Saguenay. 

Additionally, Alco built another 69 units for foreign sale including the Algerian Railways, Central do Brazil, Consolidated Railways of Cuba (before trade bans with Cuba were enacted), Ferrocaril del Pacifico, and National de Mexico (the above production roster includes only domestically sold RS3s). 

From the historical narrative it is fascinating that it was Alco, not EMD, which pioneered the endearing locomotive design still regularly used in freight service today; the common road-switcher.  

  1. Home
  2.  ›
  3. Diesel Locomotives
  4.  ›
  5. RS3

Recent Articles

  1. Canadian National Railway

    Jun 07, 23 10:50 PM

    The Canadian National Railway has been in operation since the World War I era and today remains one of the seven North American Class I systems.

    Read More

  2. Buffalo, Rochester and Pittsburgh Railway

    Jun 07, 23 10:48 PM

    The Buffalo, Rochester and Pittsburgh Railway was a regional line once serving central Pennsylvania and western New York. It became part of the B&O in 1932.

    Read More

  3. Alco "RS3" Locomotives

    Jun 07, 23 10:44 PM

    The RS3 proved to be the builder's bestselling road-switcher by far with some still in service today.

    Read More

  4. Buffalo Creek and Gauley Railroad

    Jun 07, 23 10:44 PM

    The Buffalo Creek & Gauley Railroad was a classic shortline in the West Virginia hills that is fondly remembered by railfans.

    Read More

  5. Alco "RS2" Locomotives

    Jun 07, 23 10:42 PM

    The RS-2 continued the success from the RS1 and led to the bestselling road-switcher of all, the RS3.

    Read More

Wes Barris's is simply the best web resource on the study of steam locomotives. 

It is difficult to truly articulate just how much material can be found at this website. 

It is quite staggering and a must visit!