Alco/EMD "RSX-4"/"MRS-1" Locomotives: Specs, Horsepower, Rosters

Last revised: December 16, 2024

As the United States entered the Korean War during the early 1950s, and then later became involved in the intensifying Cold War with the Russians, the military felt it needed a road-switcher with the flexibility and redundancy for service abroad on foreign railroads that utilized a wide-range of gauges.

As a result, it turned to Electro-Motive (EMD) and the American Locomotive Company (Alco), at the time the leading manufacturers of diesel locomotives, to come up with a design.

Overview

What was known by EMD as the MRS-1 ("RSX-4" by Alco), which stood for "Military Road Switcher" or "Military Road Service," was very similar in appearance among each builder although they differed slightly.

They saw just around two decades of ownership by the military while some were sold to civilian railroads. Over the years many were scrapped but some were saved and a few remain operational.

The MRS-1 was an interesting locomotive design and grew largely out of Alco's early RSD-1 manufactured during the early 1940s for use during World War II in Europe, as well as here in the States.

Photos

Texas State Railroad MRS-1 #8 is seen here at Palestine, Texas, circa 1982. This unit was manufactured by Alco in 1953 as U.S. Army #2101. Mike Bledsoe photo. American-Rails.com collection.

As the country became involved in the Korean conflict, and later the Cold War, the United States Army Transportation Corps (USATC) believed a model capable of operating in multiple gauges among a range of track conditions on railways around the world (particularly in the Eastern countries such as Korea and Russia) was needed to move troops and materials quickly and efficiently if those systems were captured.

The general basis of the design was established by the USATC, which sent out requests to all major manufacturers of the era to submit bids and specific designs (others then included the Baldwin Locomotive Works and Fairbanks Morse). Ultimately, only General Motors' Electro-Motive Division and a General Electric/Alco partnership were interested.

Military Requirements

There were three primary prerequisites for the design; it must utilize a low-profile (height) due to tighter clearance issues in Europe (otherwise known as the loading gauge); adjustable trucks that could fit gauges ranging from standard (4 feet, 8 1/2 inches) to broad (5 feet, 6 inches); and finally interchangeable couplers for use with multiple, differing railroads.

EMD produced 13 examples between March and June of 1952, #1808-1820 (serial numbers 15873-15889). Both designs were similar; EMD's was 13-feet, 6-inch high with a wheelbase of 57-feet, 5-inches.

It featured the builder's tried and proven 16-cylinder, model 567B prime mover capable of producing 1,500 horsepower. Additionally, it carried 60:17 gearing, C-C trucks, and weighed 109 tons. However, it is here where things are said to have turned badly for Electro-Motive.

Alaska Railroad MRS-1 #1601 (built as U.S. Army #B2049) is seen here in Anchorage, Alaska during September of 1980. Keith Ardinger photo. Author's collection.

Traditionally, EMD at the time only offered its standard engine with 1,500 horsepower and did not wish to change the specifications for the 1,600 horsepower requested by USATC.

However, only under extreme pressure did EMD finally relent, changing the fuel injection settings and allowing for an added 100 horsepower. In the end, arguably due to politics, Alco/GE was awarded the contract for their version of the MRS-1 in one of the very few instances where Electro-Motive was beaten out by the competition during that era.

Data Sheet and Specifications

RSX-4 Specifications (Alco)

Alco Class	E1670
Entered Production	3/1953
Years Produced	3/1953-10/1953
Model Specification	RSX-4
Engine	244, V-12
Engine Builder	Alco/Schenectady
Horsepower	1,600
Carbody Styling	Alco/General Electric
Length (Between Coupler Faces)	55' 11"
Weight	240,000 Lbs.
Dynamic Brakes	Yes
Trucks	C-C
Truck Type	Trimount
Wheelbase	13' 2"
Wheel Size	40"
Traction Motors	GE 752
Traction Generator	GE581
Gear Ratio	60:17
Tractive Effort Rating	30,700 Lbs. at 11 MPH.
Top Speed	70 MPH

Alco's most noticeable visual difference was the shape of its carbody featuring a beveled, smooth roof-line across the entire length of the frame; in contrast EMD's sported a "V"-shaped roof-line ending at the cab while the short hood was square giving the locomotive an uneven appearance.

Alco's MRS-1s, utilizing components from General Electric, were manufactured between 1953 and 1954. They carried the 12-cylinder, 244 model prime mover that could produce 1,600 horsepower and were slightly longer at 55 feet, 11 inches (weight was the same).

In total, Alco manufactured 83 examples that were listed #2041-2123 (serials 80324-80406). Additionally, 50 of the locomotives carried steam generators for as-needed passenger assignments and their road numbers were designated with a "B" prefix.

The military wound up paying an exorbitant amount of money for the MRS-1 models produced by both EMD and Alco; they averaged about $500,000 each, which was more than three times the amount of a standard road-switcher (such as a GP9 or RS3).

Production Rosters

MRS-1

Total Built = 13

Owner	Road Number(s)	Serial Number(s)	Date Built
U.S. Army	1808	15873	3/1952
U.S. Army	1809	15874	3/1952
U.S. Army	1810	15875	3/1952
U.S. Army	1811	15876	3/1952
U.S. Army	1812	15877	3/1952
U.S. Army	1813	15878	4/1952
U.S. Army	1814-1816	15879-15881	4/1952
U.S. Army	1817	15882	5/1952
U.S. Army	1818	15883	5/1952
U.S. Army	1819	15884	5/1952
U.S. Army	1820	15885	5/1952

RSX-4

Total Built = 83

Owner	Road Number(s)	Serial Number(s)	Date Built
U.S. Army	B-2041, B-2042	80357-80358	4/1953
U.S. Army	B-2043	80359	4/1953
U.S. Army	B-2044	80360	4/1953
U.S. Army	B-2045 thru B-2047	80361-80363	4/1953
U.S. Army	B-2048	80364	4/1953
U.S. Army	B-2049, B-2050	80365-80366	4/1953
U.S. Army	B-2051	80367	4/1953
U.S. Army	B-2052	80368	4/1953
U.S. Army	B-2053 thru B-2055	80369-80371	4/1953
U.S. Army	B-2056	80372	4/1953
U.S. Army	B-2057	80373	4/1953
U.S. Army	B-2058	80374	4/1953
U.S. Army	B-2059	80375	4/1953
U.S. Army	B-2060	80376	4/1953
U.S. Army	B-2061	80377	4/1953
U.S. Army	B-2062	80378	4/1953
U.S. Army	B-2063	80379	4/1953
U.S. Army	B-2064	80380	4/1953
U.S. Army	B-2065	80381	4/1953
U.S. Army	B-2066	80382	4/1953
U.S. Army	B-2067	80383	4/1953
U.S. Army	B-2068	80384	4/1953
U.S. Army	B-2069	80385	4/1953
U.S. Army	B-2070	80386	4/1953
U.S. Army	B-2071 thru B-2072	80387-80388	4/1953
U.S. Army	B-2073	80389	4/1953
U.S. Army	B-2074	80390	4/1953
U.S. Army	B-2075	80391	4/1953
U.S. Army	B-2076	80392	4/1953
U.S. Army	B-2077	80393	4/1953
U.S. Army	B-2078	80394	4/1953
U.S. Army	B-2079	80395	4/1953
U.S. Army	B-2080	80396	4/1953
U.S. Army	B-2081	80397	4/1953
U.S. Army	B-2082 thru B-2084	80398-30400	4/1953
U.S. Army	B-2085	80401	10/1953
U.S. Army	B-2086	80402	10/1953
U.S. Army	B-2087 thru B-2090	80403-80406	10/1953
U.S. Army	2091	80324	10/1953
U.S. Army	2092 to 2094	80325-80327	4/1953
U.S. Army	2095	80328	4/1853
U.S. Army	2096	80329	4/1953
U.S. Army	2097	80330	4/1953
U.S. Army	2098	80331	3/1953
U.S. Army	2099	80332	6/1953
U.S. Army	2100	80333	4/1953
U.S. Army	2101	80334	4/1953
U.S. Army	2102	80335	4/1953
U.S. Army	2103	80336	4/1953
U.S. Army	2104	80336	4/1953
U.S. Army	2105	80337	4/1953
U.S. Army	2106 thru 2108	80335-80337	4/1953
U.S. Army	2109	80338	4/1953
U.S. Army	2107 thru 2116	80339-80349	4/1953
U.S. Army	2117	80350	4/1953
U.S. Army	2118	80351	4/1953
U.S. Army	2119	80352	6/1953
U.S. Army	2120	80353	6/1953
U.S. Army	2121	80354	6/1953
U.S. Army	2122	80355	6/1953
U.S. Army	2123	80356	6/1953

In typical government fashion, the entire fleet of 96 units were never employed as intended. Once the locomotives were ready for service all were sent to USATC's Transportation Materiel Command facility at Marietta, Pennsylvania and parked.

Only one actually made it overseas, EMD #1818, which performed testing on Germany's Deutsche Bundesbahn by the Army between 1952 and 1955. The rest of the brand new units remained stateside in storage until 1970 when the Pentagon deemed them superfluous, no longer needed for military service on foreign railroads.

Some eventually did find work in the different branches such as the Air Force, Army, and Navy. Additionally, one civilian line, the Alaska Railroad, purchased many second-hand for use in freight service; 13 Alcos and 5 EMDs.

Alaska Railroad MRS-1 #1605 (ex-U.S. Army B-2055) at Anchorage, Alaska during January of 1982. This particular MRS unit (which stood for either "Military Road Switcher" or "Military Road Service") was a 1953 product of Alco while others were constructed by Electro-Motive.

Preservation

Incredibly, numerous examples of these interesting locomotives were ultimately preserved; some are even operational and at least one, a former Alco, operates in freight service on the Texas State Railroad (former US Army #2101) as of June, 2014.

Unfortunately, many of the EMD's were scrapped but four are still known to exist and one is on display at the US Army Museum of Transportation at Fort Eustis, Virginia.

There are also more than 20 examples of Alcos preserved, scattered around the country from Maryland to California. If still there, what was formerly #2108 is believed to be rusting away at Camp MacKall (a special forces training area) in Fort Bragg, North Carolina.