The Most Powerful Locomotive In America Was So Loud It Was Banned From Cities And So Hot It Melted Pavement. Here’s A Close Look


I’ve been spending a lot of time visiting the largest railroad museum in America, the Illinois Railway Museum. Through all of my visits, one locomotive has caught my curiosity more than any other thanks to its sheer size, power, and insanity: Union Pacific’s Gas Turbine-Electric Locomotive, or GTEL. The locomotive is not only the most powerful built in the United States, but the turbines behind that power produced a deafening roar and heat that cooked birds and bridges.

A Quest For Power

As the Illinois Railway Museum notes in its history of the Union Pacific’s Gas Turbine Locomotive, the trains came out of the Union Pacific Railroad’s quest for more power. The railroad started experimenting with turbines back in the late 1930s; in April and May 1939, the railroad tested a pair of steam turbine-electric locomotives that were produced in a collaboration with General Electric. At the time, train history site Utah Rails notes, Union Pacific was looking for a replacement for steam and something more advanced than the diesels of the day. The steam turbine-electric locomotive used an oil-fired boiler to produce steam to turn a turbine. That turbine was paired with a generator,  and tractive effort was achieved through electric motors. The locomotives looked on the outside like the diesels of the day.

Steam Turbine
Union Pacific Railroad

Ultimately, the steam turbine-electric locomotives proved to be unreliable, sometimes encountering failures that required other kinds of locomotives to finish the journey. The turbine-electrics never entered regular service and were returned to GE in June 1939. UP kept the collaboration going for another two years before deciding to stop chasing the technology. Right around this time, the railroad entered its now famous Big Boy steam locomotives into service, and it wouldn’t even be a decade before Union Pacific would flirt with different technologies for locomotives again.

As Utah Rails writes, Union Pacific was still hungry for power. In 1946, it had 154 diesel-electric locomotives on hand, but none of them were in freight service. Instead, the railroad saw success in running its Big Boy steamers in freight use. UP, like other railroads, began looking into how it could adapt diesel for freight. But there was a problem: a Big Boy could produce about 7,000 horsepower at 70 mph, yet a typical diesel of the day like an EMD F3 or an Alco FA produced about 1,500 horsepower. To get diesels to near or equal the amount of power as a steamer, locomotives were lashed up with power units and the whole thing was controlled from the cab. Here’s an example of what this looks like:


According to Diesel Power Magazine, Union Pacific closely watched fuel prices and wasn’t fond of the price of diesel. In addition, those diesels required expensive maintenance. The railroad wanted a cheaper solution.

General Electric Develops A Gas Turbine-Electric Engine

Around this time in the latter part of 1940s, General Electric used what it learned in aviation and restarted development on gas turbines for locomotives. Union Pacific, seeing the potential for lower running costs, wanted in. GE partnered up with manufacturer American Locomotive Company, or Alco, and in 1948 the companies put a beast into testing. Initially tested on the New York, Chicago and St. Louis Railroad and the Pennsylvania Railroad, the Alco-GE number 101 produced 4,500 horsepower and looked like a diesel.

General Electric


A year later, the unit would be transferred to Union Pacific, where it became unit 50. Over the span of nearly two years, UP put over 100,000 miles on the locomotive, taking it all over the rail line. The railroad was impressed enough with the unit that before number 50 was returned, Union Pacific ordered ten of them. Number 50 went back to GE in 1951 and a year later, the railroad got the first production units.

How The GTELs Work

How these locomotives work is similar to a diesel-electric, but with a different kind of engine. Union Pacific’s GTELs used a GE Frame three-turbine engine to drive a generator. That generator produced electricity, which found its way down to the traction motors.

General Electric

Another difference between a diesel and the turbine units was the kind of fuel used. The GTEL units were fueled using heavy fuel residual oil. Documents from Union Pacific and General Electric note that fuel to be Bunker C, a black heavy fuel that has the consistency of molasses at room temperature. This meant that the fuel had to be heated to provide a reliable flow to the turbine. To achieve this, heaters were installed into the locomotive’s fuel tanks to warm the sludge to 200 degrees.

The residual oil was also too heavy for the turbine to start. Thus, the starting procedure involved using the locomotive’s auxiliary diesel generator to spin up the turbine. The turbine would then start on diesel. Then, after the turbine was running fast enough it would be fed the heavy fuel oil.

General Electric

Huge Fuel Tanks

This is really only the start of the oddities with these locomotives. Six of the first-generation 4,500 HP units pulled in air through huge side louvers that could be opened and closed depending on need. But engineers found that this air intake design meant power loss from the heating of the air. And the compressor blades got coated in oil and dirt. This led to a design change, moving intakes from the sides to the roof. These first locomotives had a fuel capacity of 7,200 gallons, or enough fuel to haul a load between Green River, Wyoming and Ogden, Utah.

Union Pacific later took steam locomotive tenders and modified them into huge 24,000-gallon tenders for the GTELs. These extended the range of a GTEL enough so that they could travel the 990-mile route between Ogden, Utah and Council Bluffs, Iowa.

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Union Pacific also considered a route from Salt Lake City to Los Angeles. However, according to an American Rails history linked by UP, the locomotives were so loud that some California cities banned them. As you would expect, a turbine engine makes a deafening roar regardless if it’s powering an aircraft or a train. Thus, as UP says, its GTELs earned the nickname “Big Blows” for their sound. Through UP GTELs’ entire run, the trains marched through farmlands and mountains where the noise and the smoke had fewer people to bother.

These Locomotives Terrorized Cities

And that sound is something else. I haven’t been able to find a clean sound clip, but the best one that I’ve found is from Railfan Depot on YouTube:

In the video, the narrator explains that Union Pacific’s GTELs, steamers, and diesels would join forces to climb up to the 8,014-foot summit on the Sherman Hill line in Wyoming. Originally built as part of the Transcontinental Railroad, trains crossed the Continental Divide through a steep up to 1.92 percent climb up to a summit of 8,247 feet. Union Pacific worked through the decades to reduce the height of the climb and the grade. A line through Cheyenne and Buford reduced the grade to 1.55 percent. And by 1953, the Harriman line reduced the grade to 0.8 percent by making trains take a longer, gentler route.

The video shows GTELs pairing up with steamers and diesels to power their way through the mountains. While the sound clip isn’t the clearest, in the video it sounds like a rumble of thunder. If you listen closely, you can then hear the sound of a steamer or diesel being drowned out by the thing. Big Blow seems pretty accurate.

Union Pacific Turbine 51
First-Generation GTEL – Union Pacific

And GTELs were more than just loud. As train history site American Rails notes, the turbines burned fuel at 1,400 degrees Fahrenheit in their combustion chambers, and under a full load, exhaust fired out of the locomotive at 150 mph with temperatures as high 850 degrees Fahrenheit. The exhaust was so hot that as the Utah State Railroad Museum notes, it caused some chaos:

The turbines had several nicknames, among them “Bird Cookers” as the engine emitted a huge column of superheated exhaust that would consume birds in flight. They also had a tendency to quickly consume oxygen in tunnels, which caused overheating and asphyxiation. When a turbine was placed on a train going east out of Ogden, the yard switcher would push the turbine under the Riverdale Road underpass to start. The turbine would flame out, and the pavement on the overpass would melt and sometimes ignite from the huge amount of heat.

You’d think that between the need for heated bunker fuel, 24,000-gallon tenders, and heat hot enough to grill a bird mid-flight that the gas turbine-electric trains were a horrible investment for Union Pacific. However, according to Utah Rails, at first it was the opposite. The railroad was impressed enough with the first ten (UP 51 through UP 60) that in 1954, it ordered fifteen more (UP 61 through 75). These second-generation gas turbine-electric locomotives had the similar spec sheet as the first-generation, but sported a different body. While the first-gens had a more traditional carbody style, the second-generations gained crew walkways like a hood unit would have. These locomotives would come to be known as “Veranda” units.

Second-Generation GTEL – Denver Public Library Special Collections, OP-17418

Another development in GTELs at this time was that the lead unit could control trailing units, though just 19 of them were apparently set up in that configuration. As the video above shows, trailing units were often diesels.

The GTELs Were Legitimately Good For Union Pacific

For a while, the GTELs padded UP’s bottom line. As Utah Rails notes, Steam power cost UP $145.14 per 1,000 gross ton-miles, while diesel ran at $84.03 per 1,000 gross ton-miles. But the GTELs, with their cheap Bunker C? They ran at $69.19 per 1,000 gross ton-miles. However, as Diesel Power Magazine writes, to maintain these cost savings the turbines couldn’t be allowed to idle. They had to be pulling a load at full power to be the most economical for the railroad. Utah Rails notes that UP was running GTELs 8,000 miles and 400 hours per month, and they were available 78 to 80 percent of the time.

In 1956, Union Pacific published Six Million Miles Experience With Gas Turbine Locomotives. In it, the railroad describes what its then 25 GTELs had achieved. The big thing, as suggested by the title, is that the locomotives had collectively traveled six million miles in four years. Together, the engines fired 227,950 hours, with one turbine clocking in at 17,266 hours all on its own.


In the document, the railroad described the locomotives as getting 360 feet per gallon at an average of 33 mph. The railroad goes on to note that as an example of the endurance of its gas turbines, in 1955 a whole ten percent of UP’s freight was pulled by a GTEL. And the GTELs moved 38.5 percent of the freight in their assigned division. The document also notes experimentation with different fuels and fuel qualities, including a locomotive that ran on propane.

Riding on the success of the 4,500-HP units, Union Pacific placed yet another order for gas turbine-electric locomotives. These would become not only the most ridiculous of the bunch, but the most powerful locomotives built in America. UP placed its order in 1955, but development problems delayed their deployment until 1958.

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A Major Design Overhaul

Numbered 1 through 30, the final run of UP GTELs saw a major design overhaul. The previous two generations of GTEL featured the locomotive and a tender. These third-generations? They came in three sections. Up front was a control cab that contained a Cooper-Bessemer FWB-6 850-HP diesel engine. This engine provided auxiliary power, as well as power to move the control unit around in a yard. Bringing up the rear was one of the 24,000-gallon tenders. And in the middle? A GE Frame 5 turbine kicking out 8,500 horsepower at an elevation of 6,000 feet. At sea level, it’s believed that the turbine could do even better, putting out 10,000 horses. However, it’s noted that the generator was rated for 8,500-HP.

That massive gas turbine unit powered four generators, which in-turn powered 12 traction motors. The control cab had six motors, as did the turbine unit. This turbine still fed off of fuel oil that needed to be heated, and this was done electrically in the 24,000 gallon tender.

General Electric

The Illinois Railway Museum says that the whole 165-foot, 11-inch consist weighs in at 849,248 pounds. Though some estimates say that loaded down with fuel, these are well over a million pounds. No matter how you look at these locomotives they’re simply gargantuan. But for more numbers, a third-generation GTEL produces 240,000 pounds starting tractive effort, and 145,000 pounds at 18 mph. That is up from 105,000 pounds in the previous generation.

These locomotives thundered their way through America’s open west, hauling heavy freight, and cooking birds.

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GTELs Weren’t Perfect

However, Union Pacific did face some problems with its gas turbine-electric locomotives. One noted problem came from the burning of Bunker C. The ash content–containing sodium and vanadium–of the gas flow corroded combustor cans, nozzle vanes and turbine blades. As Turbo Machinery Magazine reported, the nozzles and first stage blades were made of a high nickel Nimonic 80A alloy, an expensive high temperature material. To slow this down, engineers used epsom salt and water to neutralize some of the effects. This improved reliability, but the time between overhauls was still between 4,000 and 5,000 hours.

And it wasn’t just expensive maintenance that was problematic for the GTELs. As the Utah State Railroad Museum notes, the turbines burned twice as much fuel as a comparable diesel. However, they won out on operating costs by running cheaper residual fuel. That cost benefit didn’t last, as developments in refining processes improved, wastes were able to become finer grades of fuel. Eventually, the cost of heavy fuel began rising, and with time, the maintenance and fuel costs caught up with the GTELs. Union Pacific began phasing them out in 1968, and the turbines hauled their last miles in 1970. Some of them didn’t even get to see a decade on the rails. The railroad admits that it made no effort to save the units.

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GTELs Eventually Disappeared

Ten of the 8,500 HP units were sold to Continental Leasing Group, with 20 going back to General Electric. In both cases, the locomotives were stripped of useful parts then scrapped. Some trucks found homes under other locomotives while the turbines found other industrial uses. Somehow, two units escaped the scrapper, with UP 18-18B getting donated to the Smoky Hill Railway and Historical Society in 1977. The Illinois Railway Museum then became its caretaker in 1993.

UP 26-26B was donated to the Ogden Union Station Museum in Utah in 1986. Sadly, both locomotives were stripped of parts before they were able to be saved. UP 26-26B is just a shell. UP 18-18B at IRM is more complete, but is missing its turbine. Both locomotives have gotten cosmetic restorations, but it appears that neither will roll under their own ridiculous power again.

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As for Union Pacific, it still continued its quest for more power. After the end of the GTELs, the railroad turned to diesel. In 1968 UP tried to fulfill its power needs with 50 EMD SD45s. These locomotives featured EMD 20-645E3A V20 engines generating 3,600 HP. The SD45s were good, but not enough for the railroad. Union Pacific reached out to EMD for more power, and the result was the behemoth EMD DDA40X.

Often cited as both the largest and most powerful diesel-electric locomotive ever built, the 98-foot, 5-inch, 475,830-pound machine is staggering. The prime movers are a pair of EMD 16-645E3A diesels. These 169.6-liter V16s made 3,300 HP each, for a combined total of 6,600 HP. And those engines are fed from a massive 8,000-gallon diesel tank integrated with the locomotive’s frame.

But even these saw retirement after UP encountered high maintenance costs.

Denver Public Library Special Collections, OP-19453

Today, the gas turbine-electric locomotives are remembered for their pure insanity. And it’s sort of amazing that Union Pacific was able to run gas turbines for more than two decades. To date, these remain the most powerful locomotives ever built in America. And despite their issues, it’s noted that each GTEL managed to travel at least a million miles before retirement.

(Photo credits to the author unless otherwise noted.)

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42 Responses

  1. There are some parallels with marine practice here. Steam turbine electric propulsion was common on ships from the 1920s to at least the 1950s and Bunker C oil was typically used for steam boilers and some large marine diesels.

    1. I don’t now how common turbo electric drive was on ships. It was used in the 20’s and 30’s by some countries (including the US) primarily because reduction gears were so difficult to make. This practice ended, though, when geared drive became more feasible. Today, steam turbines are pretty much limited to nuclear-powered vessels. Except in the case of *some* submarines where isolating the turbine from the prop/impeller gives some real sound isolation advantages, pretty much all nuclear vessels have a mechanical connection from turbine to prop. Turbo electric drive is becoming more common on warships and some cruise ships as hotel power becomes a bigger and bigger draw.

      1. The most powerful steam turboelectric plant, at least pre-WWII, was in the SS Normandie of 1935, 200,000 peak hp. Wasn’t a hugely popular technology at the time, traditional steam turbines offered comparable speed and power for less construction and R&D costs and complexity (but more fuel consumption), while diesel was getting more and more popular for lower speed economy oriented applications.

  2. This is a truly bonkers piece of engineering. Running a jet engine on Bunker fuel in a tunnel…and then roasting birds mid-flight in open air due to the superheated exhaust jet.

    The 50s are truly the decade of “Why not? Why shouldn’t I build it?”

  3. I’m curious as to when and why the quest for “moar power” came to an end. Domestic US freight is now 100% diesel-electric with pretty standardized locomotives, so why is that good enough today when it wasn’t good enough in the past?

    Also, I can’t imagine the filthy emissions that came from burning bunker oil. Yeccchhh…

    1. I think railroads basically decided it’s easier and more efficient to add and subtract 3000-4500 hp diesels as needed than it is to have huge locomotives that are more power than needed a lot of the time. Plus if one diesel breaks down you have one or more than can limp the train along, whereas if the only locomotive breaks, you’re SOL.

        1. Modular power is now inside the locomotives as well. Genset locomotives replace the single huge diesel with 3 or 4 truck engines that get switched on to match the load. Union Pacific uses them as yard switchers since they can run one engine while idling or running light engine and add power as cars are coupled

  4. As I am wont to do, have to engage in pedantry over your mixing of numbers here. If you’re going to base the article around something being the strongest, it’s necessary to give the same measurements for all examples. Drawbar HP, turbine horsepower and diesel generator horsepower are 3 different things. On the latter two they’re even unrelated to the engine’s total output, as the traction motors determine that.

    Drawbar HP or tractive effort would be the way to go here.

    1. We stuck with horsepower figures for the turbines and for the diesel engines because those were the figures that Union Pacific and the museums use to compare between the railroad’s steam, diesel, and gas turbines. And when these GTELs are described for their power, it’s usually in horsepower.

      Weirdly, UP doesn’t note tractive effort on its blurbs about its historical locomotives, just horsepower. It’s similar for the museums actually storing these units. I only found tractive effort within the archived technical documentation.

      That said, you are right that I confusingly used drawbar HP, and that has been changed accordingly.

  5. This was a terrific read – many thanks! I used to live next to one of the busiest UP double-track mainlines in the country. Occasionally, trains from both directions would manage to meet right behind my house. A “foamer” at heart, I greatly enjoyed that. I can’t imagine the glorious cacophony that I would’ve gotten to hear if those locomotives had been GTELs! I’m little less keen on the thought of breathing in remnants of bunker C fuel though.

  6. I’ve always wondered why they used ordinary V engines and not a Napier Deltic style design. They got 5600 HP out of one back in 1957 before it threw a rod, with modern alloys they should be able to get a lot more.

  7. Mercedes, great piece here on the Bird Burners.

    Keep these RR and RV articles coming! You are a great writer and have a lot of knowledge and passion on these topics, stuff like this sets Autopian apart from the other websites.

  8. “In the document, the railroad described the locomotives as getting 360 feet per gallon at an average of 33 mph.”
    Now, this math might be wrong, but 360 feet is about 0.0681 miles.
    So, I’m assuming that means 0.06 miles per gallon, and that’s just a ridiculous number…. I love it!
    Great story to read nonetheless too!

    1. That number is what caught my eye!!

      And it’s actually .0681 miles per gallon. I just increased their fuel efficiency by 12%! (Just messing with you).

      I’m always amazed when I see the fuel tank sizes for planes, cruise lines, trains, etc. I just can’t fathom pulling up to the gas station and putting 24,000 gallons in the tank (ya definitely gotta get a couple scratchers and a slim while you wait, right?).

  9. I enjoyed the read. I have no particular interest in the subject, but enjoy lengthy articles with lots of history and detail. I was unfamiliar with heavy fuel oil and its prevalence in marine freight shipping for such a long time.

  10. Love any and all train posts!

    Trains Magazine produced a book about the GTEL’s that went in depth about their development and operation.

    BTW, glad you made the move from that ‘other site’ to the Autopian! Keep up the great work.

  11. Great article. Those GTELs were indeed insane- UP started flirting with railroad mad science to find a single locomotive solution to the Rockies.

    Some time you ought to come down here to St. Louis and check out the National Museum of Transportation… no GTELs here, but we DO have a Big Boy (you can climb in the cab) as well as an Aerotrain and a few other interesting pieces.

  12. Several of these engines made there way to a company in Kansas City to be rebuilt and powered dredges on the Missouri River and far beyond. I guess the noise was not as big a problem on the water.
    Great article about these behemoths!
    I hope your Wedding was a great success.

  13. Great article. I never thought I’d take the time to read up on trains but have thoroughly enjoyed all your recent write ups.
    This take me back to the days of being a kid in the backseat of my parents car trying to watch trains go by as we’d travel down the highway. I never knew how powerful some of the old locomotives were! As someone who works around jet engines it’s wild to think of one running a train, burning up pavement and just wailing down the open track blasting heat into the air. I can just imagine incredibly loud compressor stalls reverberating through the cab as the turbine struggles for oxygen in a mountain tunnel somewhere!

  14. This is excellent Traintopian!
    I love the technological hubris of the ‘50s—and think it’s impressive that basically everything was figured out with pencil & paper (and slide rulers!). I liken it to the Victorian Age in UK, except they threw more cast iron & rivets at stuff while America just added moar powah to everything.

  15. Interesting! Thanks for writing this.
    It’s so strange reading -for a while at least- diesel’s couldn’t match steam! It still blows me away the HP numbers achieved with steam.

    BTW i cant miss the chance to link one of the coolest train videos ever. So far this is the only large steam engine i’ve ever seen running at full load.Hopefully they’ll do something similar with the Big Boy!

    1. I seem to remember a paper on the feasibility of powdered iron as a fuel for some type of engine. The only product of it is rust. Don’t think that would be good for the engine either.

      Should keep the elves away, though

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