Trains And Locomotives Wiki

The GE (General Electric) ES44AC is a type of six-axle, 12-cylinder, 4,400hp diesel locomotive built by GE Transportation Systems from 2004 to present (though first introduced in early 2002).

A typical UP ES44AC or C45ACCTE.

The model is part of the "Evolution Series" (also known simply as a "GEVO"); the current locomotive line from the company, and is also considerably the leading diesel locomotive model of the locomotive industry as it has received numerous awards and nominations, along with surpassing sales of past and preceding models such as the SD40-2.

Over 4,000 or so have been built over the last decade (with over 5,000 total from the actual series or line; and counting), and many are still currently being manufactured as of today; more-so than its rival: the EMD SD70ACe. Many variants also exist, and have been built for export to numerous foreign nations (such as Brazil, Kazakhstan, Australia, and Egypt).

Companies such as Union Pacific (UP), BNSF, CSX, Canadian Pacific (CP), KCS (Kansas City Southern; including KCSM), Ferromex (FXE; including Ferrosur), and IAIS (Iowa Interstate) were among the many customers to purchase the model. While later companies such as NS (Norfolk Southern), CN (Canadian National) Cemex (despite only receiving one unit), Cerrejón (coal field in Colombia), Cartier Railway, and CREX (Citicorp/Citirail leasing) have since ordered units.

It is the initial successor to the AC4400CW.


During the early-2000's, GE began reaching a new milestone to expand beyond their preceding successes with their Dash 9 and AC model lines. After officially becoming the leading locomotive manufacturer in the United States, North America, and the rest of the world in front of long-term arch-rival EMD since the 1980's, the company decided to develop a next-generation locomotive line even more advanced and high-tech than its predecessors: the "Evolution Series". Although intended to be an 'evolution' from preceding models and lines, the Evolution Series was also meant to be "Tier 2" compliant under the US EPA's once-strict "Tier 2" emissions policy for internal combustion engine emissions regarding vehicles such as those utilizing diesel engines (semi trucks and actual diesel locomotives), as well as reducing fuel consumption to last greater distances and to help further conserve resources. To achieve said values, GE increased the overall size of the stroke and bore of their existing long-running 7FDL-16 prime-mover, which therefore decreased the amount of cylinders needed to attain 4,400hp in contrast to the preceding 16-cylinder, four-stroke, 7FDL-16. Hence, the introduction of the revolutionary 12-cylinder, four-stroke, GEVO-12.

A brand-new ES44AC leading a consist of two SD70ACe's and another ES44AC unit on an intermodal in 2005.

Originally codenamed "AC44EV" ("EV" for "Evolution"), the ES44AC (the first model to debut from within the line) began as a series of preproduction testbeds demonstrated to UP (receiving 5) and BNSF (receiving 30) from 2003 to 2004. Although they were nearly flawless upon their initial introduction, they unfortunately suffered numerous technical difficulties regarding some of the computer software which was previously implemented on the AC4400CW, as well as having suffered numerous electrical issues. Hence, BNSF began to simply convert their otherwise "flawed" GEVO testbeds into what was eventually dubbed as the "ES44DC": the DC-traction counter-part (the initial successor to the Dash 9), which was eventually ordered by the railroad prior to the redevelopment of the ES44AC by a joint effort between UP and GE (classified as the C45ACCTE or AC45CCTE, and built to their own unique specifications). Upon successful troubleshooting with UP's testbeds, the ES44AC became an instant success and green-lit production with GE by placing an order consisting of a total of 100 units (numbered 5248-5347, but eventually renumbered 5348-5362). UP has since received a total of more than 1,063 units in recent years; a record-breaking amount for GE. Though, numerous running changes have since occurred upon the first deliveries of units beginning sometime in 2005. Such changes revolving around the electronics, controls, and microprocessor software; aside from the cab size (as of 2013): making the more recent models dubbed as a "C45AH" ("H" meaning, "heavy"), which are very similar and reminiscent to CSX's specialty ES44AH units as well as bearing some similarities to the UP's recent SD70AH fleet acquisition from EMD.

As for BNSF, the railroad was somewhat reluctant and was still placing orders on traditional DC-traction ES44DC's to supplement their vast amount of preceding Dash 9's as opposed to taking an advantage of receiving more ES44AC's after 2006. From 2007-2008, they continued receiving ES44DC's until they began placing orders on more ES44AC's from 2009-2010. During that same year, a revolutionary variant of the ES44AC debuted: the A1A-trucked ES44C4, which is a six-axle, four-motor version of the AC-traction ES44AC which consists of a classic configuration which was commonly found or prominent on most early, first-generation six-axle diesels like EMD's E units (having the center axle unpowered with the remaining four on opposing axles powered with individual traction motors). Since the initial debut of the ES44C4, BNSF has since replaced orders for subsequent ES44AC units in favor of ES44C4's, and are expecting more deliveries by the end of 2016; making a grand total of over 1,000 ES44C4's in comparison to the 721 preceding ES44DC and 690 ES44AC units ordered by the railroad.

Cemex #81: the only ES44AC unit ordered and delivered to the large Mexican-based cement corporation, #81 was built to CSX specifications.

As of 2015, the ES44AC is no longer manufactured domestically, and is only available for export. Furthermore, Tier 3-compliant exports are not permitted for domestic use (such as CN's recent ES44AC's), and can only be towed to their respective destinations in accordance with the US EPA's rules, effective January 1st 2015. The succeeding Tier 4-compliant locomotive models (the ET44AC and ET44C4) have been in production since early 2015, and are the current domestic freight models in the Evolution Series line


CSX on the other-hand, didn't become interested in placing orders until after the last remaining ES44DC (now classified as "ES40DC" as a result of being de-rated to 4,000hp) was delivered sometime in early-2008. Though, once they began placing orders, numerous additional running changes began to occur like with UP's C45ACCTE fleet. Such changes revolved around the revival of the AC radial truck (or "AC-truck") as opposed to the conventional or more common "hi-AD" truck and the implementation of "High Tractive Effort" software, as well as including a unique feature known as a "rail cleaner": which blows air across the railhead to clear leaves, snow and moisture to help the locomotive maintain steady pulling power. Thus, making their exclusive ES44AC variant known as the "ES44AH" (the "H" meaning, "heavy", "high", or "High Tractive Effort"), which is considerably heavier compared to other units of the latter (weighed at 432,000 lbs. as opposed to the usual 415,000 lbs.) due to having thick metal plating underneath the frame (reminiscent of CSX's "Phase 2" SD70MAC units), with the addition of having a radial truck or bogey model/style meant to give an additional amount of wheel adhesion, tractive effort, and a sharper turning radius on heavy-haul applications for use on their heavy coal trains or coal drag service throughout the Appalachian mountain region, where the use of 3 to 4 units (two front, one rear or two front, two rear and vice-versa) on an average 60 to 70-car unit coal train traveling with a set of lead units navigating a steep gradient with sharp, winding curves, with a DPU or CTE unit assisting the rear and slowing and/or shoving the train at steady slow speeds is fairly common.

Other Customers

For CP, the railway ordered their earlier ES44AC units (numbered 8700-8759) with the self-steering radial truck, but eventually declined and resorted to the more affordable or cheaper to maintain "hi-AD" truck to utilize on their later units (ranging from 9350-9379). They currently operate a total of 291 units for use in general service alongside their AC4400CW's.

IAIS #516: the 30th anniversary unit wearing a Rock Island-inspired scheme.

Iowa Interstate (IAIS) was one of the first Class 2 railroads or regionals in the United States to purchase new, GE diesels for the first time in many years, on top of purchasing their very first entirely new, non-second hand diesels. The railroad has since received 14 units. In an enthusiastic move, the railroad painted one of their units (IAIS #513) into an livery reminiscent of the Chicago, Rock Island and Pacific (Rock Island) railroad, Who's former trackage they operate on. 3 additional ES44AC's were ordered during late 2014 and delivered early 2015, despite having declined numerous times before. One other unit in particular (IAIS #516), was also painted in an livery reminiscent of another version of the Rock Island's paintscheme to celebrate the regional's 30th anniversary.

Savatran (a subsidiary of the Evansville And Western) ordered 3 ES44AC units (numbered 1912, 1982, and 1986) and were delivered in February 2012. The units are numbered for the years that Penn State University won national college football championships. These units are used on heavy-duty coal trains along the ex-L&N line in which they service.

NS (Norfolk Southern) painted 10 of their ES44AC units in which they acquired in 2012 for the company's 20th anniversary into paintschemes dedicating fallen flags on their system: defunct railroads which no longer operate, and are known as "heritage units". The heritage units wear schemes designed by artist Andy Fletcher. NS has since received 166 ES44AC units as of 2014.

Kansas City Southern's newer ES44AC units have similar updated features that are included with UP's C45AH's, such as improved lighting, reduction of hazards (having a better frame design), and strengthened accessories: such as having improved collision posts, an improved anti-climber, and an improved fuel tank design.

Remarkably, CN was the last major Class 1 railroad in North America to place an order for AC-traction diesel locomotives. The road decided to place an order of 60 ES44AC's in 2011, and additional 45 in late-2014. These units are the first completely new locomotives purchased by the company since 2007. As of mid-2015, less than a few months after receiving their final Tier 3-compliant ES44AC, CN began receiving new Tier 4-compliant "ET44AC" units, and are expected to receive at least 50 to 60 by early 2016.

LNG and Tier 4 Demonstrators

Sometime in late-2012 (albeit obscure within most of the railfan community),

GECX 2024 and 2025 as seen on the UP.

GE unveiled their first Tier 4-compliant ES44AC demonstrators (GECX 2014 and GECX 2015; renumbered GECX #2023 and GECX #2024) which are meant to be capable of providing more reduced fuel consumption and lower emissions far greater than current GEVO's. Several others have also been built: #2021-2043. It should also be noted that the locomotive model is an inch longer than the preceding ES44AC variants: being 74 ft. 2 in. to accomodate the size of the cooling system built to follow requirements implimented by the EPA. On another note, the center of the carbody or engine hood is noticeably taller, giving an otherwise pronounced "humpback" or "hunchback". 

During 2013-2014, they successfully completed numerous demonstrations on UP; most notably on Donner Pass. They have also found their way on various other host railroads such as CSX, KCS, BNSF, and NS. Said demonstrators are actually ET44AC testbeds, and are scheduled to end their demonstration tours or runs by late-2015 or early 2016.

An LNG (Liquified Natural Gas) Demonstrator GECX #3000, was also developed and was showcased. Tests and demonstrations are currently underway, for GE and EMD have both attempted to experiment with LNG-fueled diesel locomotives like with what they initially attempted 20 years earlier.

Units 2026 and 2027 were rebuilt in June 2017 as regular ET44ACs and delivered in July 2017 for North American Coal in New Mexico


The ET44AC ("T" for "Tier" or "ET" for "Evolution Technology") is the Tier 4-compliant version of the ES44AC which began production in mid-2015 at GE's Erie, PA facility. Although not the first production Tier 4 model (despite being the first prototype), the ET44C4 debuted at GE's newer Fort Worth, TX facility and began testing and delivery for BNSF several months prior.

It should be noted that the production version of the ET44AC is noticeably different compared to its testbed counter-part, for it retains the previous hood design, only fitted with a cooling and exhaust system that includes an improved design (having a distinct "box" with vents and grilles to reduce exhaust fumes and engine noises as well as emissions). The radiator section is very reminiscent of an AC6000CW or an Australian ES44DCi, for it's lengthened to meet cooling demands under the US EPA's Tier 4 policy.

CSX, UP, NS, CN, and TNMR are currently receiving deliveries of the model.

A UP ET44AC revealing its noticeable changes in contrast to earlier units of the Tier 2-compliant model.


Numerous variants or versions also exist:

  • ES44ACi (or TE33A) - Kazakhstan version of the original
  • ES40ACi - 4,000hp Egyptian version built for Egyptian National Railways painted in two distinct liveries (blue for passenger trains and red/black for freight trains).
  • C45ACCTE - UP's version of the ES44AC (as shown above).
  • ES44AH - CSX's version of the ES44AC (as shown above).
  • C45AH - Variant of an existing C45ACCTE.
  • ES45AC - 4,500hp designation for UP and CSX (sometimes an alternative to the other names listed).
  • ET44AC - Tier 4-compliant version equipped with larger cooling system and larger cab hood.
  • ET44AH - CSX's version of the ET44AC; Tier 4-compliant version of the original ET44AC model.


Here is a list regarding the specifications of the model:

Model ES44AC ET44AC
Wheel arrangement C-C C-C
Length 73' 2" 74' 6" (lengthened to accomodate cooling system and larger cab hood)
Weight 416-432,000 lbs. 426,000 lbs.
Height 15' 5" 16' 1" (over antennas)
Engine control system GE CCA GE CCA
Engine (prime-mover or motor) GEVO-12 GEVO-12
Number of cylinders 12 12
Traction horsepower 4,400 4,400
Traction alternator GMG205 GMG205
Traction motors GEB13 GEB13
Maximum speed 72 to 75mph 72 to 75mph
Continuous tractive effort 166,000 lbs. -
Starting tractive effort 183,000 lbs. -
Dynamic braking effort 117,000 lbs. -
Fuel capacity 5,000 gals. -

Prime Mover GEVO-12
Stroke cycle 4
Bore/Stroke 250 x 320 mm
Cylinders 12

188.5 L

Aspiration Turbocharged
Gross hp 4,500
Traction hp 4,400
RPM idle/low idle 440/330
RPM full load 1050
Weight 42,300 lbs.

Spotting Differences

There is often a confusion between the ES44AC and preceding models or locomotives such as the AC4400CW.

The location of the front radiator cabinet located on every ES44AC is meant for housing the DC-to-AC rectifying equipment. Said cabinet located behind the cab, classifies it as an "Auxiliary Cab" or "Aux Cab" rather than being a typical "American Safety Cab" or "wide-cab" found on such models as the C44-9W and C40-8W.

  • The most notable external differences should be with the rear radiator section: it is separated into two sections and has a much more "sloped" appearance compared to the plain, flat appearance of an AC4400CW's radiator section.
  • From an aerial view, two small radiator grid fans are noticeable on the smooth part of the radiator.
  • All GEVO models are equipped with an "Auxiliary Cab" (or "Aux Cab"), which is basically a variant of the existing wide-cab or American Safety Cab found on models such as the AC4400CW which includes a cabinet meant for housing the DC-to-AC inverters for the traction motors.
  • Another noticeable difference is the height of the handrails.
  • UP's recent C45AH units are equipped with slightly larger cabs as a result of their new weight specifications (seen above).
  • There is less of a gap or a "hump" in the middle or center of the carbody compared to models like the AC4400CW.
  • The rear hood (despite numerous running changes) has a much more symmetrical appearance as opposed to being more round and angular.
  • Typically, a small box is located behind the radiator cabinet, and is used as a crank switch for the AC invertors.

Like every other diesel locomotive built by GE, the name designation lists or describes the stats of the ES44AC:

  • "ES" - For "Evolution Series"
  • "44"- The horsepower rating; being 4,400hp
  • "AC" - AC-traction powered through AC-traction motors; but usually with a DC current, which is then inverted or rectified through the equipment housed within the front radiator cabinet located on the conductor's side of the cab.


A typical BNSF ES44AC painted in the company's "Heritage 3" livery.

Ironically, during the redevelopment or troubleshooting stages of the ES44AC testbeds, UP began receiving post-production AC4400CW units classified as an "AC45ACCTE" or "AC44CWCTE", which contained some of the features implemented on today's GEVO units, which have also since made their way on numerous preceding members or units of the AC4400CW owned by the railroad, as well as several subsequent Dash 9's.

Unlike its predecessor, the ES44AC has a conventional control stand as opposed to the more common desktop control stand found on most other wide-cab diesel locomotives.

Only a handful of GEVO units have been scrapped and/or retired due to having been involved in a wreck. Said units have since been replaced.

Numerous ES44AC units received by UP and CSX are often classified as an "ES45AC", and are commonly rated at 4,500hp: the maximum gross horsepower output.

Ironically, BNSF's vast GEVO "armada" (as dubbed by railfans) has since replaced the C44-9W or Dash 9 as being the main locomotive used by the railroad.

One GEVO unit, UP #7605 (a former GECX demonstrator), retained its original scheme until 2008 when it was repainted in the standard "Armor Yellow" livery.

IAIS # 512 is ex-CSX #950 from a cancelled order in 2009, although another unit with the same number was built in 2011 for CSX.

Like every other model of GEVO, the ES44AC was originally one of the only diesel locomotives to feature the once-exclusive Nathan K5HL and subsequent K5HLL airhorns. Though, both horn models have since found their way on various older GE diesels from within the CSX system (most notably their C40-8 and C40-8W's).

Oddly, the Tier 4 demonstrators utilized by GECX include two-tone horns built-in to the rear hood radiator section ("wings" or "fins") as well as having unique, hybrid 3-chime variant or version of the K5HL/K5HLL horn (K3HL) mounted towards the side of the large, distinct center portion of the carbody.

CREX has acquired a total of 100 ES44AC units for lease service and expect to have several more by 2015.

UP #7964 was the 5,000th GEVO officially built, and once wore special banners to prove it until they were removed in August 2016

UP #7400 wears special banners sponsoring Breast Cancer Awareness.

UP #2010 is specially numbered and painted to sponsor the 100th anniversary of the Boy Scouts of America scouting organization for young boys.

GECX Demonstrators Gallery



Trains Magazine Locomotive 2010 Kalmbach Publishing


Cranking a GE Evolution locomotive for an outbound train

Trains Magazine Vol. 73, Issue 12: Pg. 18


GE ES44AC Tier 4 Long Hood Forward (5 4 15) Garyville, LA

Two-tone horn sounding for a grade crossing from a GECX Tier 4 GEVO demonstrator leading a slow coal drag long-hood forward.


CN 2284 GEVO locomotive 8th notch load test

Load testing of a CN GEVO from within the cab.