EMD GP40 Series


The versatile EMD GP40 series, manufactured by Electro-Motive Division (EMD), were built between 1965-1971. The GP40 is powered by EMD’s 16 cylinder, 645E3 prime mover, producing 3,000hp, and much like its predecessor, the GP35, was successful and proved reliable for many class 1 and shortline carriers. Acting as a replacement for the successful GP35, the GP40 used many of the same components, the most evident change between the two being the introduction of an alternator system, instead of the previously used DC generator. Throughout production, many variations of the GP40 were produced, such as the GP40-2, and the passenger variant, the GP40P, and GP40P-2. The GP in the model designation signified general purpose, further emphasizing the versatility of the unit.



The most noteworthy GP40 variation was the reliable GP40-2. The Dash 2 specification related to various electronic equipment upgrades, and other advanced systems. These units began production in 1972, and continued until 1986, with many of the original GP40s being rebuilt to GP40-2 standards. In total, 1,143 units were built for railroads in the United States and Mexico. The GP40-2 sold well, however, despite the high sales numbers, it did not sell as well as the original GP40. The reason for this being that EMD began introducing six axle locomotives into the lineup, which garnered the interest of railroads, due  to their increased pulling power. However, the GP40-2 outsold its GE counterpart, the B36-7, and outnumbered it in sales volume by 913 units. Still, many GP40-2s remained in service, as they were best attributed to fast freights, while the six axle units were designed for heavy hauling.


This version of the GP40 was built between 1977-1978, and was powered by an EMD 645F prime mover, which offered an additional 500 horsepower than the standard GP40, bringing the total amount to 3,500 horsepower. This locomotive was built as a test bed for the future EMD GP50 and SD50 series. Twenty-three examples of this locomotive were built, with ten of the units being delivered with experimental HT-B trucks. The main spotting feature of these locomotives were the flared radiators, and the experimental trucks. Four railroads in total purchased this locomotive including the Atchison Topeka & Santa Fe (ATSF), ordering ten, the Southern Pacific (SP), purchasing four, Southern Railway, purchased six high short hood examples, and Union Pacific (UP) purchased six. The ATSF and Southern versions included the standard EMD Blomberg truck, while the other railroad’s GP40X’s were delivered with HT-B trucks.

KL Whitehead photo


With the versatile 4-axle design of the GP40, it was soon realized that it could be a useful passenger locomotive. The Central Railroad of New Jersey was the first to place an order for a passenger version of the GP40, with Southern Pacific following suit. These locomotives, built in 1968, were used on the CNJ’s Raritan Valley Line, and North Jersey Coast Line, and were funded through a grant provided by the New Jersey Department of Transportation (NJDOT). These locomotives were equipped with a steam generator to supply power to passenger cars, which were later equipped with a diesel head end power (HEP) generator when operations were controlled by NJ Transit, and were then rebuilt by Morrison-Knudson in the late eighties, and designated as GP40PH-2.

Rear of a CNJ GP40P, showing the extension for the HEP steam generator

The GP40P-2, built for the Southern Pacific in 1974, was similar to the GP40P, except that the frame of the locomotive was a few feet longer than the GP40P. This locomotive included the dash 2 electronic upgrades, much like the standard GP40-2. These units were used for Southern Pacific’s commuter service, serving southern California. SP #3197, was painted in a special bi-centennial paint scheme in 1976, and was a sought after sight for railfans and daily commuters alike. Throughout the eighties, due to the decline and eventually termination of Southern Pacific Commuter service, the locomotives were rebuilt into standard GP40-2’s, and had their HEP generator removed.

GP40PH/PH-2/PH-2B Rebuild

Throughout the late eighties, NJ Transit began a rebuild program focusing on their ex-CNJ GP40PH’s. These upgrades included upgraded electronics to dash 2 standards, the addition of a diesel head end power generator, powered by Caterpillar, and a complete rebuild from the frame to the roof. These locomotives were numbered 4100-4112, and designated GP40PH-2. Currently, many rebuilds in this order have been taken out of revenue passenger service and reassigned to work train duty, however, two examples, 4100 and 4102, remain in revenue passenger service. In addition to the NJ Transit order, Metro North placed an order for one example of the locomotive, and was delivered to the railroad in 1992, and numbered 4906.

Later, in need of additional motive power, and seeing the versatility of the GP40PH-2 locomotives, NJ Transit would contract Morrison-Knudsen to build six more passenger based GP40s to be designated GP40PH-2A. These locomotives were built from standard freight GP40s, and derived from various railroads throughout the country. These locomotives were ordered in 1993, and were numbered 4145-4150. This order is currently in storage, however, due to the equipment shortage experienced by NJ Transit, 4145 was sent to MARC in Maryland in return for the use of MARC single level coaches by NJ Transit.

NJT GP40PH-2 4217 at Hoboken. Stewart Wells photo

The final order consisted of 19 locomotives, which were to be rebuilt by Conrail’s Juniata Shops, located in Altoona, Pennsylvania. These locomotives were of Penn Central descent, and were Conrail units before being rebuilt for NJ Transit. They were completed during 1993-1994, and continue to serve on NJ Transit to date. In the model designation, the P=passeneger, and the H=head end power. The A and B signify the locomotive order.


Built by Morrison Knudsen, the GP40FH-2 was built using the cowl of an F45 locomotive, and the EMD standard cab design. It was fitted with an EMD 645 prime mover and a caterpillar HEP generator. Twenty-one examples of this locomotive were built, as 15 were delivered to NJ Transit, and 6 to Metro-North.


In the late eighties, MARC, Maryland’s commuter railroad, ordered 6 GP39H-2 locomotives, rebuilt from standard GP40’s  of New York Central, Penn Central, and Milwaukee Road descent. These locomotives featured a redesigned 12 cylinder prime mover, which resulted in a 700 horsepower reduction, to 2,300 horsepower, from the standard 3,000. In addition, these locomotives were equipped with head end power (HEP) units powered by Cummins.


In 1996 Connecticut Department of Transportation (CDOT) purchased six GP40-3H locomotives which were rebuilt from standard GP40s. Recently, all the GP40-2H locomotives were rebuilt into GP40-3H locomotives for use on the recently opened Hartford Line.

GP40WH-2 & GP40MC

Additional MARC units ordered by Morrison-Knudsen were designated GP40WH-2, which included a widecab and flared radiators. Like the GP39H-2, these units were equipped with a Cummins HEP generator. These units entered service in 1994, hauling revenue passenger services for MARC. A unique aspect represented on these locomotives was the addition of a gyro light, which flashed atop the cab of the locomotive, instead of ditch lights below the pilot. The Federal Railroad Administration (FRA) allowed these units to operate without ditch lights, as they were not mandated at the time of production. One GP40WH-2 remains on the MARC roster to date, as well as one purchased by CSX for work trains and office car specials. Most of the ex-MARC GP40WH-2s were sent to Motive Power Industries (MPI) to be rebuilt into MP32PH-Q locomotives for use on Florida’s highly anticipated SunRail passenger service.

The Massachusetts Bay Transportation Authority (MBTA) also operates GP40 passenger locomotives, purchasing 25 GP40MC locomotives from AMF Technotransport. These units were rebuilt in the late 1990s from former Canadian National GP40-2LW locomotives. Over the past few years, these units have been rapidly replaced with HSP46 locomotives built by MPI, however, a few examples remain in revenue service for the time being.

Canadian GMD Variations

General Motors Diesel (GMD) was EMD’s Canadian division, based in London, Ontario. Their GP40 variant, the GP40-2W, was built with the Canadian safety cab, which designated the W, meaning widecab. The Canadian safety cab was the product of Canadian National’s focus on the safety of their train crews. These locomotives were built between 1974-1976, for Canadian National, and a passenger version for GO Transit.

Another variation, designated the GP40-2L(W) included a modified frame that increased the height, and reduced the weight of the locomotive. These modifications were made to CN specs to accommodate a larger fuel tank of 3,000 gallons, as opposed to the standard fuel tank of 2,300 gallons. These units were classified by Canadian National as GF-430a units.

Further variations of GMD units existed in passenger service throughout Canada, as GO Transit ordered 8 GP40TC units in the late 1960s. These units served on GO Transit for almost 20 years before being sold to Amtrak in the late 1980s.

Photo credit Canadian Railway Observations.

GP40 Specifications

Wheel ConfigurationB-B
Wheel Diameter40 in
Wheelbase9 ft
Length59’ 2”
Width10’ 4”
Height15’ 5”
Weight250,000 lbs
Max Speed65 mph
Tractive Effort61,000 lbf
Gear Ratio62:15

GP40-2 Original Owners

RailroadNumber of Units Purchased
Atlanta and West Point1
Alaska Railroad10
Baltimore and Ohio218
Boston and Maine Railroad18
Chesapeake and Ohio Railway95
Ferrocarril Chihuahua al Pacifico29
Denver and Rio Grande Western Railroad37
U.S. Department of Transportation1
Detroit, Toledo and Ironton20
Florida East Coast24
Georgia Railroad2
Kansas City Southern Railway4
Louisville and Nashville Railroad17
St. Louis San Francisco Railway25
St. Louis Southwestern Railway56
Seaboard Coast Line25
Ferrocarril Sonora-Baja California15
Southern Pacific68
Texas, Oklahoma and Eastern Railroad3
Western Maryland Railway35
Western Pacific15
Western Railway of Alabama1


Central Railroad of New Jersey (CNJ)13

GMD Variants

Canadian National233 GP40-2LW

35 GP40-2W

GO Transit10

Morrison Knudsen/Juniata Rebuilds



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