The EMD SD70ACe: My Favorite Locomotive. Architectural Style and Symmetrical Design Makes the ACe Distinctive. Part One: Burlington Northern Santa Fe, Ferromex, and Kansas City Southern ACes.

Article and photographs by Divi Logan.

Introduction: The ACe Element. Design Differences Draw Attention to the Specifications of the EMD SD70ACe.

The designation EMD SD70ACe means: EMD (Electro-Motive Diesel, the builder); SD means Special Duty, indicating that it is a six-axle locomotive; 70 denotes the series of locomotives that appeared in the 1990s; AC means it has AC traction, and the e is for enhanced features, first used in 2005.

The nose design of the ACe reminds me of architecture, like the keystone of an arch. It is a design that sets it apart from other locomotives, just as an element of ornamentation sets a building entrance apart from another.

BNSF ACe #8508
BNSF ACe #8508 is shown in two views as it leads a mixed freight consist westbound through Riverside, Illinois. The vertical aspect and geometrically symmetrical nose design stand out as it approaches the crossing at Riverside Road. 28 June 2022.

Known for its environmentally friendly design and geometrically distinct nose shape, the ACe meets Tier 4 emissions regulations and includes more technological advances than the SD70MAC. The nose shape is defined by taller side walls just over five feet in height and the compounded-angled nose top. The reasons for the design changes over earlier SD70 models are:

  • Improve crashworthiness
  • Meet updated FRA safety standards
  • Integrate with the new, more upright cab front
  • Accommodate revised electronics and HVAC systems

II. The Gallery: ACes by Railroad Company.

BNSF ACes

BNSF ACe #8413
BNSF ACe #8413 leads a westbound consist through Hinsdale, Illinois. 17 September 2020.
BNSF ACe #8419
BNSF ACe #8419 is second in this locomotive consist heading eastbound through Riverside, Illinois. 10 April 2024.
BNSF #8433, EMD SD70ACe
BNSF EMD SD70ACe #8433 leads a hopper consist eastbound through Riverside, Illinois. 8 June 2021.
BNSF ACe #8433
BNSF ACe #8433 leads an eastbound consist through Riverside, IL. 8 June 2021. Photo location: Platform 1 (North Platform). Riverside METRA Station.
BNSF ACe #8345
BNSF ACe #8435 leads a westbound mixed freight consist through Riverside, IL. 26 April 2022. The rectangular windows in the ACe are a design feature retained from the SD70M-2 locomotive. Medium telephoto.
BNSF ACe #8448
BNSF ACe #8448 is part of a westbound consist through Riverside, IL. 10 October 2022.
BNSF ACe #8538
BNSF ACe #8538 holds at the station in Riverside, Illinois. The engineer waited for a priority westbound consist to come out of the Cicero Yard. 1 May 2024. ** The photo was taken with permission of the engineer. Never cross in front of a stopped train and never touch rolling stock. It is railroad property. Had this train been moving, I would not have come this close to the locomotive. Note that I am behind the platform’s yellow safety line. **
BNSF ACe #8566 Side View
A side view is shown of BNSF ACe #8566, third unit in this locomotive consist heading westbound in Riverside, Illinois. 13 September 2024.
BNSF ACe #8566
BNSF ACe #8566 is third unit in this locomotive consist heading westbound in Riverside, Illinois. 13 September 2024.
BNSF ACe #8764
BNSF ACe #8764 is third in the locomotive consist rolling westbound through Riverside, Illinois. 30 July 2024.
BNSF ACe #9066 and BNSF ACe #8782
BNSF ACe #8782 is the second unit in a westbound hopper consist through Riverside, IL. 16 March 2022.
BNSF ACe #9014
On two occasions in May 04 2024, BNSF ACe #9014 is second in an eastbound locomotive consist through Riverside, Illinois. Left photo: 15 May 2024. Right photo: 22 May 2024.
BNSF ACe #9027
BNSF ACe #9027 leads a westbound tanker consist through Riverside, IL. Trailing unit: BNSF ACe #9256, The signal bungalow is on the northeast corner at Cowley Rd, ENS Crossing ID: 079497N. Medium telephoto. 12 April 2022. Signal gantries disappear in the distance looking east towards the Cicero Yard.
BNSF #9027 leads the westbound tanker consist as it crosses Riverside Road between structures at the Riverside METRA Station.
BNSF ACe #9256
BNSF ACe #9256 trails BNSF ACe #9027 for a tanker consist westbound through Riverside, IL. 12 April 2022. Wide- angle. Signal aspects: Green over red on Main 2 facing westbound. This means the train is cleared to proceed as the maximum authorized speed. The route ahead is lined and unoccupied.
BNSF ACe #9066
BNSF ACe #9066 leads this consist westbound through Riverside, Illinois. 16 March 2022.
BNSF ACe #9066
BNSF ACe #9066 leads a westbound hopper consist through Riverside, IL. 16 March 2022.
BNSF ACe #9267
BNSF ACe #9267 leads a westbound hopper consist through Riverside, Illinois. 26 June 2023.
BNSF ACe #9267. Right side hood angle with H3 livery.
BNSF ACe #9269
BNSF ACe #9269 is the end DPU, or distributed power unit. Stands for Distributed Power Unit, a locomotive set capable of remote-control operation in conjunction with locomotive units at the train’s head end. DPUs are placed in the middle or at the rear of heavy trains (such as coal, grain, soda ash and even manifest) to help climb steep grades. LaGrange, Illinois. 6 July 2023.
BNSF ACe #9298
BNSF ACe #9298 leads a westbound consist through Riverside, Illinois. 1 August 2022. Photo location: Platform 1. Riverside METRA Station.
BNSF ACe #9303
BNSF ACe #9303 leads an eastbound hopper consist through Riverside, Illinois. 1 August 2022.
BNSF ACe #9303
BNSF ACe #9303 leads an eastbound hopper consist through Riverside, Illinois. Side angled view. 1 August 2022.

Ferromex ACes

Ferromex is the largest railroad operating company in Mexico. it was founded in 1998 and followed the privatization of most of the country’s state-owned railroads. It is owned in the majority by Grupo Mexico, and the minority share is owned by Union Pacific.

The colorful liveries of these locomotives are a standout for railfans on the lookout for unusual or historic color schemes. The colors signify those of Mexico’s national flag- red, green, and white. The colors add to visibility at railroad crossings.

Ferromex Special “Corporate Blue/Executive Blue” Livery.

This unusual livery is displayed on FXE ACe #4029. It is subdued compared to the livery shown below on FXE #4048, the standard company livery with the tricolor scheme.

This special livery is in dark blue and gray, with a red cab displaying Mexico’s national flag. The Ferromex lettering is clean and large across the hood of the locomotive. There is minimal striping, with the usual tricolor striping absent from this scheme.

FXE #4029 in special corporate blue livery
FXE ACe #4029 shows off the special and rarely-noticed corporate blue livery implemented in the mid-2010s during a company refresh. 31 August 2022. Riverside, IL. Locomotive specs: Model: EMD SD70ACe. Serial and frame number: 20106395-015. Order number: 20106395. Built: 04/2011.

Ferromex Tricolor Livery

FXE locomotive ACe #4048
Ferromex ACe #4048 is third in this westbound consist through Riverside, Illinois. 19 October 2022. Locomotive specs: Build date: 06/2011. Serial Number: 20106395-034. Order No: 20106395
Frame Number: 20106395-034.
Ferromex FXE ACe #4048
The colorful livery of Ferromex locomotives is displayed in this side view of ACe #4048. It is third in this consist. 19 October 2022. Riverside, Illinois.

Kansas City Southern ACes

Kansas City Southern locomotives display the classic livery called Southern Belle. It is in deep red, a rich yellow, and a dark green called Brunswick green. The Southern Belle was the company’s flagship train.

KCS ACe #4045
Kansas City Southern’s classic livery stands out on ACe #4045 in this westbound locomotive consist. Hinsdale, Illinois. 24 April 2023. Locomotive specs: Model: EMD SD70ACe. Serial and frame number: 20066856-016. Order number: 20066856. Built: 08/2007.

Glossary of Railroad Terminology

  1. AC: Alternating current, an electrical current that reverses its direction at regularly recurring intervals.
  2. Ballast: a heavy substance (such as rocks or water) placed in such a way as to improve stability and control.
  3. Crossing, active, grade, crossing: the area where a highway and a railroad cross at the same level. The area includes the tracks, road, and traffic control devices for traffic traversing that area.
  4. Consist: the order of locomotives and cars that make up a train. Consist lists include sequence, roles, and sometimes technical details of the rolling stock.
  5. DC: Direct current, an electrical current flowing in one direction only and substantially constant in value.
  6. ENS sign: Emergency Notification System signs provide crucial information to first responders and railroad police in the event of an emergency situation along the rail line. Information on the blue and white signs includes phone numbers, a unique identification designation, and the primary operating railroad.
  7. Gantry: (rail transport) a structure erected over one or more railway tracks, carrying one or more signals. Smaller structures usually have a single support, and larger structures are supported on both sides.
  8. Livery (or paint schemes): the colors schemes on the rolling stock. Examples include the bold black and white “horsehead” scheme of Norfolk Southern and the “Building America” scheme of Union Pacific, including a winged shield and waving flag.
  9. Locomotive: a powered vehicle that runs on rails and is used for moving railroad cars.
  10. Reporting marks: these are the unique identifiers that indicate the ownership of rail cars and other railroad equipment. This is essential for tracking and managing railroad assets. These are assigned by the Association of American Railroads (AAR).
  11. Rolling stock: the wheeled vehicles owned and used by a railroad or motor carrier.
  12. Signal aspect: combinations of red, yellow, and green lights that tell train crews about track conditions.
  13. Traction: the adhesive friction of a body on a surface on which it moves.
  14. “DPU (Distributed Power Unit).” Types of Trains, Union Pacific Railroad, http://www.up.com/about-us/funstuff/rrtalk/train-types. Accessed 3 Feb. 2026.

Resources

  1. Bing. “EMD SD70ACe What Does That Designation Mean?” Bing Search Results,
    https://www.bing.com/search?q=EMD%20SD70ACe%20What%20does%20that%20designation%20mean%3F&qs=n&form=QBRE&sp=-1&ghc=1&lq=0&pq=emd%20sd70ace%20what%20does%20that%20designation%20mean%3F&sc=12-44&sk=&cvid=B9FEDB781AD24A6C82C1549B674F64B0. 31 January 2026.
  2. Wikipedia contributors. “EMD SD70 series.” Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 29 Jan. 2026. Web. 1 Feb. 2026.
  3. RRPictureArchives.net. “Pictures of FXE 4048.” RRPictureArchives.net, https://www.rrpicturearchives.net/locoPicture.aspx?id=163414.
  4. Divi. Ferromex #4048 at Station Platform. 2026. JPEG image.
    Divi. Ferromex #4048 in Multi-Locomotive Consist. 2026. JPEG image.
  5. Resources
  6. Operation Lifesaver, Inc. “Track Safety Basics.” Operation Lifesaver, https://oli.org/safety-near-trains/track-safety-basics. Accessed 31 Jan. 2026.
  7. U.S. DOT Crossing Inventory Form. Federal Railroad Administration. FRA Rail Crossing Locator. “Crossing ID 174022F.” 1 September 2025.
  8. U.S. DOT Crossing Inventory Form. Federal Railroad Administration. FRA Rail Crossing Locator. “Crossing ID: 079522U.” 8 July 2025.
  9. “Alternating current.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/alternating%20current. Accessed 30 Jan. 2026.
  10. “Ballast.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/ballast. Accessed 3 Feb. 2026.
  11. “Direct current.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.Merriam-Webster.com/dictionary/direct%20current. Accessed 30 Jan. 2026.
  12. United States, Department of Transportation, Federal Railroad Administration, and Federal Highway Administration. “[Active Crossing, Grade Crossing (Crossing)].” Railroad–Highway Grade Crossing Handbook – Revised Second Edition (2019), U.S. Department of Transportation, 2019, pp. 2,5. PDF file, https://railroads.dot.gov/sites/fra.dot.gov/files/2024-10/GXHandbook2019FRAFHWA.pdf.
  13. “Union Pacific Railroad Livery Description.” Microsoft Copilot, 30 Jan. 2026.
  14. “Locomotive.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.Merriam-webster.com/dictionary/locomotive. Accessed 30 Jan. 2026.
  15. “Traction.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/traction. Accessed 30 Jan. 2026.
  16. Microsoft Copilot. “Explanation of the Term ‘Consist’ in Railroading.” Conversation with Divi, 30 Jan. 2026.
  17. “Southern Pacific ‘Daylight’ Livery on UP #1996.” Bing, https://www.bing.com/search?q=Southern%20Pacific%20%22Daylight%22%20Livery%20on%20UP%20%231996&qs=n&form=QBRE&sp=-1&ghc=1&lq=0&pq=southern%20pacific%20%22daylight%22%20livery%20on%20up%20%231996&sc=8-46&sk=&cvid=CD3D8E4731CA4A0AB19544C584E61238.
  18. “Rolling stock.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/rolling%20stock. Accessed 31 Jan. 2026.
  19. “signal gantry.” Wiktionary. 14 Jan 2025, 18:10 UTC. <https://en.wiktionary.org/w/index.php?title=signal_gantry&oldid=83606739&gt; 1 Feb 2026, 21:32.
  20. Bing. Search Results for “signal aspect indicator”. Microsoft, https://www.bing.com/search?q=signal+aspect+indicator. (bing.com in Bing). Accessed 1 Feb. 2026.
  21. McGonigal, Robert S. “Railroad Reporting Marks 101.” Trains Magazine, 5 Feb. 2024, http://www.trains.com/trn/train-basics/abcs-of-railroading/railroad-reporting-marks-101/.
  22. “Railroad Reporting Marks.” Bing,www.bing.com/search?pglt=929&q=railroad+reporting+marks&cvid=3e65c4ffc74a488a896e6617524b2fd7&gs_lcrp=EgRlZGdlKgYIAxBFGDsyBggAEEUYOTIGCAEQABhAMgYIAhAAGEAyBggDEEUYOzIGCAQQRRg8MgYIBRBFGDwyBggGEEUYPDIGCAcQRRhBMgYICBBFGEHSAQgxNTQzajBqMagCCLACAQ&FORM=ANNTA1&PC=U531. Accessed 3 Feb. 2026.
  23. Microsoft Copilot. “Explanation of the Nose Design of the EMD SD70ACe.” Copilot Conversation, 5 Feb. 2026.
  24. Microsoft Copilot. “Annotated Consist Entry for BNSF SD70ACe Units #9066 and #8782 at Riverside Road (ENS 079498V).” Copilot Conversation, 5 Feb. 2026.
  25. Microsoft Copilot. “Visual Roster Entries for BNSF SD70ACe #9066 and #8782, with Updated Photo Integration.” Copilot Conversation, 5 Feb. 2026.
  26. Microsoft Copilot. “Side-by-Side Comparison Panel for BNSF SD70ACe Units #9066 and #8782.” Copilot Conversation, 5 Feb. 2026.
  27. Wikipedia contributors. “Ferromex.” Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 1 Feb. 2026. Web. 10 Feb. 2026.
  28. Copilot. Explanation of Ferromex Locomotive Livery. 10 Feb. 2026.
  29. “BNSF 5741.” RR Picture Archives, http://www.rrpicturearchives.net/locoPicture.aspx?id=14931 .(rrpicturearchives.net in Bing)
  30. “BNSF 5741.” RR Picture Archives, http://www.rrpicturearchives.net/locoPicture.aspx?id=14931 (rrpicturearchives.net in Bing).
  31. “BNSF Railway’s H1, H2, and H3 Paint Schemes Side by Side.” RR Picture Archives, http://www.rrpicturearchives.net/showPicture.aspx?id=426918 (rrpicturearchives.net in Bing).
  32. Copilot. Ferromex Locomotive 4048 at Station — Thumbnail Crop. 10 Feb. 2026. AI‑generated image based on user‑uploaded source, Microsoft Copilot, https://copilot.microsoft.com/. . Accessed 10 Feb. 2026.
  33. Copilot. Explanation of the Special Livery Applied to Ferromex Locomotive FXE #4029. Microsoft, 11 Feb. 2026.
  34. Grupo México. Grupo México: Building Infrastructure for the Community for Generations. http://www.gmexico.com/en/, Grupo México, 2020.
  35. KCS 4045, an ES44AC wearing the Southern Belle–inspired freight colors (red, yellow, black), photographed at Hinsdale, Illinois on 24 April 2023. Photo by [Your Name]. Livery history consulted: The Diesel Shop — KCS Paints. Accessed 11 February 2026.
  36. Logan, Divi. Photo of KCS 4045. Historical references: The Diesel Shop — KCS Paints; American‑Rails — Southern Belle. Location and date: Hinsdale, Illinois; 24 April 2023. Article accessed 11 February 2026.
  37. “Pictures of FXE 4029.” RRPictureArchives.net, http://www.rrpicturearchives.net/Locopicture.aspx?id=155185. Consulted for photographic reference and livery verification of Ferromex locomotive FXE #4029; used to confirm special dark‑blue/gray corporate variant.
  38. “Pictures of FXE 4048.” RRPictureArchives.net, http://www.rrpicturearchives.net/Locopicture.aspx?id=155184 Consulted for photographic reference, roster confirmation, and verification of the standard Ferromex tricolor livery applied to FXE #4048.
  39. “Pictures of KCS 4045.” RRPictureArchives.net, RRPictures.net, n.d., https://www.rrpicturearchives.net/Locopicture.aspx?id=89934. Accessed 11 Feb. 2026.
  40. Copilot. Explanation of the Green‑over‑Red Railroad Signal Aspect. Microsoft, 17 Feb. 2026.
  41. Copilot. Definition and Explanation of the General Code of Operating Rules (GCOR). Microsoft, 17 Feb. 2026.
  42. Copilot. Explanation of the Green‑over‑Red Westbound Railroad Signal Aspect. Microsoft, 17 Feb. 2026.
  43. United States, Department of Transportation, Federal Railroad Administration. U.S. DOT Crossing Inventory Form: DOT/AAR No. 079497N. Federal Railroad Administration, 8 July 2025. FRA Rail Crossing Locator, https://www.fra.dot.gov/railcrossinglocator. Accessed 19 Feb. 2026.

    More ACes to come! Enjoy them! Welcome to all visitors!

    Happy and safe railfanning!

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