wow, BNSF ordering A1A version ES44AC units?! Weird.

[see more recent post where it starts to make more sense]

Text copied since the content is behind a subscriber login (yea, I know that's not exactly kosher by blog rules, but hey, it's a cool story):

Published: Monday, January 26, 2009
FORT WORTH, Texas - BNSF Railway has reportedly placed an order with General Electric for 25 six-axle ES44AC locomotives to be equipped with four rather than six traction motors per unit, altering the normal C-C truck configuration to A1A-A1A. The designation is said to be ES44AC-4. 

The concept behind the order is that once the train has reached a specific speed, more than four traction motors are unnecessary. Fewer traction motors also reduces weight and maintenance considerations. 

The units are expected to be assigned to fast, high-priority intermodal trains on the railroad's former Santa Fe Transcon between Chicago and Southern California. The units are expected to be delivered later this year.
Have to say that this move seems very illogical to me - 4 traction motor locos are for speed instead of traction, but AC locos are mostly about traction, so this is a complete combination of 2 contrasting design goals.  A1A ES44DCs I could understand more, but even then it still makes more sense to go with BB trucks (presumably the locos are too heavy for only 4 axles however).  This is more strange because there haven't been any mainline 4-motor freight units sold in the US in close to 2 decades now...

[from trains.com]


  1. Dear Mr.Mytas: I would like to comment on the blog about the A1A ES44AC-4. I have followed the Genesis series since it was launched in 2004-5. Ge has used all of it's resources to sell these units to the railroad industry-low fuel consumption, pulling power so on. I did notice starting in 2006 that there was crack in the foundation with this series. In 2006 the AAR did their annual Emissions/Fuel Test. It showed the ES44 12 cylinder engines fuel and emissions were the same as EMD's 710 series, but the EMD has 4 more cylinders. That is not all. The test also showed the GE Genesis engine uses 12 gallons more per hour in Run 8 then the 710-2 engine.
    The Austrialian railroads have been shying away from the Genesis engine because they are heat/cold and altitude sensitive. You have noticed they have ordered many ACE's in the last 3 years and current owners who prefer the GE's have been ordering the FDL AC44 series.
    Another issues that has dogged the series and GE as a whole is that they have a problem with wheel slip on wet rail and unique profile track.
    Remember in the 1970-80 period GE tried to sell the industry their U-36-B. It slipped like it was on ice. They came back with the B40-B in the 80's-90's. In fact Amtrak bought 50 of them because they were not happy with EMD. These units were disasters. They slipped like crazy and performed very poorly in inter city service. In fact they un-retired the F40's to cover for them until they received their new F59 units from EMD.
    About 1 year ago, the History Channel had a 1 hour program on the rail industry. In one segment they covered the booming business of the container business. They covered a double stack BNSF train from the LA Harbor to Chicago. They paid particular attention to the pull over the Cajon Pass. The train was about 6500 feet and total tonnage was about 7000 tons. The train was pulled by 4 Genesis ES-44DC. Train had to stopped at the base of the hill to pick up a set of SD-40's. The locomotive engineer said they needed to add the helpers because they would not of made it over the summit because of wheels shipping. I nearly fell out of my chair. I couldn't believe what I was hearing. How could a train with this much state of the art power, with this weight have wheelslip. If you remember from the 70's-80's and early ninties the SD-45's used about 4 units to pull the same of weight over the Cajon. Which brings us to the other reason I believe BNSF asked GE to build this A1A units. They are are inconsistent with maintaining speed and they are slow to pull. GE is trying to correct an inherent problem with their series with a band aid correction. The SD-45 was a very successful unit for the Santa Fe because it proved to the mechanical department that 6 axle unit could pull like a mule and run like a race horse. This was the death null of the 4 axle unit.Union Pacific (UP) has been concentrating their fleet of SD-70ACe's on double stack trains. In fact I read a report in Railway Age the engine of choice for the LA Basin and the UP's own transcom was the SD-70ACe. Why. Because they pull and run very well. I thing you are right to say they are going against the natural strengths of the AC transmission. But I need to say again they will have to address GE main weakness-wheeelslip. They are going to have 4400HP going to a total of 4 axles instead of 6 axles. They will need to add weight to the units like they did in 2001 with CSX AC44 units. The CSX units slipped so badly(Trains had a cover story article on this problem) GE upped the weight from 210,000lbs. to 230,000lbs. CSX calls these units heavies(note: it was strange the article stated that CSX did not have problem with their EMD's SD-70MAC's slipping. But EMD worked with the CSX closely and added weight to their units so they would match the axle load with the GE').
    So I have a feeling GE will weigh down the ES44AC-4 to pick up the adhesion of the units and drop the potential wheelslip. The two extra (dead) axles will allow GE to increase the weight of the locomotives but keep the axle load down.
    Lastly, what is really strange is that Candian National said in a press release recently that they are buying their SD-70-2 units to pull their double-stack traffic out of Vancouver,BC. The managers said the units pull well in the mountains and run well across the plains. Sounds like SD-45-2 is alive and well in 2009.
    Thank you for allowing me to reply to your blog. If you have anything on your mind I would like to hear your thoughts. Thank you again.

  2. I hadn't realized just how much trouble GE has had with wheel-slip - that makes this move all the more puzzling to me. Neither GE nor EMD was particularly successful with their late high-horsepower 4-axle units, and it seems natural that the railroads quickly moved to six axles for even their top intermodals. Heck, I'm surprised that there hasn't been at least more experimental pushes for BB-BB span-bolster units or self-steering D-D units for drag traffic. It's always telling when railroads with strong allegiances to one builder go to the competitor - CSX buying so many of the new SDs for example.
    (your note about the Amtrak 8-40BWs is similarly-interesting - always thought they were an interesting but strangely-allocated units. Now i get why they were so quickly relegated to yard duty.)
    I still would presume that a 4-axle ES44AC lightened just enough to keep the axle-load within tolerances would pull better than these units with wasted axles even if heavier because there would still be less weight on the actual pulling-axles (axle-weight, not total weight matters more, no?). In this case I can see the AC justification, since you do need every bit of traction on a high-horsepower 4 axle, or even A1A unit, but AC costs so much more that I don't see how the cost savings of 2 fewer motors can counteract the extra expense.

  3. One advantage I could see with AC A1A is the stronger dynamics AC motors offer. BNSF has a rule that if you cannot control train speed with dynamics alone (no air) train speed must be reduced to 55. Perhaps they are thinking AC will make up for the loss of dynamic capability.