This 1.2 Million Pound Beast Is The World’s Largest Running Steam Locomotive And Seeing It In Person Will Break Your Brain

There’s a rare steam locomotive thundering its way down the rails around America right now. Union Pacific Big Boy 4014 is an incredible piece of history. It’s the largest operational steam locomotive in the entire world and Big Boy 4014 is the very last of its kind that’s even capable of running itself down the track. Seeing this marvel of engineering in person is a mind-melting experience and one so grand it practically grounds small towns to a total halt. I got to see this majestic locomotive and I’m happy to tell you there’s still time for you to see it, too.

Just 25 Big Boys were ever built for the Union Pacific Railroad, of which only 8 survive today. Big Boy No.4014 is the only Big Boy in the world that moves under its own power. Its sheer size and weight also make it the largest steam locomotive in operation today. The locomotive is a point of pride for the Union Pacific and its employees. The colossal locomotive has been going on tours of the United States since its restoration was completed in 2019.

This year, 4014 has embarked on the “Heartland of America Tour,” which started in Cheyenne, Wyoming on August 28. The locomotive is making whistle stops in Arkansas, Colorado, Illinois, Iowa, Kansas, Missouri, Nebraska, Oklahoma, and Texas. Just three of those stops will be days in which the train will be on public display for all to see for free.

One of those stops was on Sunday in Rochelle, Illinois. I waited in clogged traffic for hours and joined possibly a few thousand people just to see this legend and it was worth every minute. You’ll get to do it, too, and soon!

The Quest For More Power

The Union Pacific Railroad has long been a railway obsessed with power. Some of history’s most powerful locomotives stormed through the American West and its mountain ranges painted in that familiar bright yellow.

Over a century ago, Union Pacific grew an unquenchable thirst for more power. As Trains Magazine writes, Union Pacific’s Overland Route between Omaha, Nebraska, and Ogden, Utah was largely flat and easily traversed by the steamers of the day. The problem was east of Ogden with the Wasatch Range. Trains traveling eastbound had to climb 1.14 percent grades, which doesn’t sound all that steep, but that’s a big deal for large, heavy trains running metal wheels on metal tracks.

The Wasatch Range had been a thorn in the Union Pacific’s backside since the completion of the Transcontinental Railroad in 1869. The railroad’s solution to the steep grade was inelegant and required locomotives to be lashed up before they finally produced enough grunt to haul loads up the grades. However, double-heading trains and using helper locomotives took time, slowed operations down, and cost the railroad money. What the Union Pacific really wanted was one locomotive that could do it all.

So, throughout the late 1800s and early 1900s, the railroad commissioned ever larger and more powerful locomotives in its obsession with beating the Wasatch Range. In 1936, Union Pacific fired another salvo at the range in the form of the Challenger 4-6-6-4 locomotive, which put up a good fight, but still required backup when hauling 3,600 short tons of freight through the range.

As a side note, Union Pacific Challenger No. 3985 was restored in 1981 and ran excursion trains until it was forced into retirement in 2010. The locomotive is being restored again so there’s a non-zero chance that one day, railfans will get to see the Big Boy alongside its predecessor.

Getting back on track here, the Challenger was great, but Union Pacific demanded more. As Trains Magazine writes, in 1936 Union Pacific established the Research and Mechanical Standards Department. Vice President Otto Jabelmann ran the department and his mission from Union Pacific President William Jeffers was to develop a locomotive capable of pulling the aforementioned 3,600 short tons up the Wasatch Range without any assistance. The railroad also wanted this locomotive of the future to be able to cruise at 60 mph with that load after the track flattened out.

The department got to work on this ambitious plan and over time, they recognized that the locomotive they needed to design had to produce at least 135,000 pounds of tractive effort and an adhesion factor of four. To put that into perspective, the Challenger fell short with its 97,352 pounds of tractive effort.

As I wrote in a previous retrospective, this quest for power would eventually lead to the absurd bridge-melting Gas Turbine-Electric Locomotive (below) and later, the mighty EMD DDA40X, but not before other experiments. One way Union Pacific thought it would defeat the Wasatch and the famous Sherman Hill was by incorporating newer technologies, as I wrote in my GTEL piece:

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.

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.

Union Pacific made sure not to put all of its eggs into the baskets of experimental technology. As it turned out, the railroad could achieve its goals, at least for a while, by doubling down on what it knew already worked: Steam.

Going back to the Research and Mechanical Standards Department, three months after its founding, the railroad sent members of the department to join a team formed at the American Locomotive Company, the chosen builder of the new $265,174 locomotive. Reportedly, the railroad had already done a lot of research, which cut development time down. The team started with the Challenger design and gave it an extensive overhaul. In doing so, the Big Boy took just six months to design and fabricate parts for the very first Big Boy and another six months to put it all together.

During the development process, the engineers found they could hit their targets by increasing the size of the Challenger’s firebox, cranking up the boiler pressure to 300 PSI, and reducing the size of the driving wheels, but tossing on four more of them.

But remember, the Big Boy isn’t just about power. The railroad also demanded a consistent cruising speed on flat ground. This was a challenge of its own. As the book, The American Steam Locomotive in the Twentieth Century by Tom Morrison writes, locomotives don’t ride perfectly between the rails of their track gauge. Train wheels have some give. Unfortunately, this means that locomotives had a tendency to slam into the rails side to side within their gauge. This makes the ride harsh and prevents a steady cruise as the railroad wants. Even worse, articulated locomotives had an additional problem of pitching and yawing from the forward drive unit.

Alco’s solution to the oscillation problem was strategically placing 7 tons of weight in the locomotive’s front casting. The engineers also added cushion springs to prevent the locomotive’s suspension from getting overloaded from bumps on the rails. In some ways, a Big Boy was simpler than a Challenger thanks to the elimination of booster, compounding, and feed water heaters. But the locomotive made up for it with complications in other ways.

A Mind-Boggling Machine

For example, Union Pacific says Big Boy No. 4014 has 967 square feet of tubes, 4,218 square feet of flues, 593 square feet of firebox, 111 square feet of circulators. In all, the Big Boy has 5,889 feet of evaporating surfaces, plus 2,466 square feet of superheating surface. Union Pacific says the original Big Boy design called for a top speed of 80 mph, but the actual locomotives got nowhere near that. A railroad representative at the Big Boy event in Illinois noted that on a good day, a Big Boy goes 60 mph and at their absolute fastest they might go 65 mph.

Everything about the Big Boy is bonkers. Technically, the Erie Railroad triplex 2-8-8-8-2 locomotives by Baldwin were heavier than the Big Boy at 860,000 pounds. However, the unique 2-8-8-8-2 triplex design incorporates the tender as part of the locomotive with its own driving wheels while the Big Boy does not. If you take the tender of the triplex out of consideration, the Big Boy’s 762,000 pounds of pure locomotive makes it the world’s heaviest steam locomotive. Load up a Big Boy with a tender and all and you’re looking at an astonishing 1.2 million pounds of train before you even lash up any freight.

If you really want to get into a debate at dinner tonight, here’s a whole table of the largest, most powerful, and longest locomotives by just about any metric you’d want to hang your hat on.

You may also ask: How did other railroads solve the problem of climbing mountains? As the National Park Service writes, other railroads just lashed together as many as ten locomotives in a line until their trains could finally climb the passes.

A Big Boy produced around 7,000 drawbar HP and had about 135,375 pounds of maximum tractive effort. Union Pacific has a helpful picture to illustrate how mind-bogglingly huge a Big Boy is. The lengthy 133 feet of the locomotive and its tender are nearly twice as long as the typical modern diesel-electric locomotive and more than half of the 232-foot length of a Boeing 747-400.

The Big Boy also wasn’t the most powerful steamer out there. A Virginian Railway AE Class 2-10-10-2 puts out a whopping 177,000 pounds of tractive effort. In other words, a Big Boy lives up to its name, but it’s hardly the only family of locomotives with some beef behind their wheels.

I’ll pass the mic to Union Pacific from here:

Twenty-five Big Boys were built exclusively for Union Pacific Railroad, the first of which was delivered in 1941. The locomotives were 132 feet long and weighed 1.2 million pounds. Because of their great length, the frames of the Big Boys were “hinged,” or articulated, to allow them to negotiate curves. They had a 4-8-8-4 wheel arrangement, which meant they had four wheels on the leading set of “pilot” wheels which guided the engine, eight drivers, another set of eight drivers, and four wheels following which supported the rear of the locomotive. The massive engines normally operated between Ogden, Utah, and Cheyenne, Wyo.

There are seven Big Boys on public display in various cities around the country. They can be found in St. Louis, Missouri; Dallas, Texas; Omaha, Nebraska; Denver, Colorado; Scranton, Pennsylvania; Green Bay, Wisconsin; and Cheyenne, Wyoming.

Big Boy No. 4014 was delivered to Union Pacific in December 1941. The locomotive was retired in December 1961, having traveled 1,031,205 miles in its 20 years in service. Union Pacific reacquired No. 4014 from the RailGiants Museum in Pomona, California, in 2013, and relocated it back to Cheyenne to begin a multi-year restoration process. It returned to service in May 2019 to celebrate the 150th Anniversary of the Transcontinental Railroad’s Completion.

I bet you’re wondering about the name and there’s an explanation for it. Reportedly, it was rumored that Union Pacific would call the locomotives “Wasatch” after their intended mission. However, it’s said that an Alco machinist wrote “Big Boy” in chalk on the smokebox of the very first locomotive, and the name stuck. That’s also why you’ll see the name Big Boy chalked on the operational No.4014, even though it wasn’t the first Big Boy.

The 25 Big Boys served Union Pacific well, accomplishing the tasks they were meant to perform. The Big Boys even aided in the World War II effort, delivering the goods at a time when traffic peaked as America needed to get material across the country fast.

The Union Pacific Big Boy crews loved their locomotives for their sheer power, reliability, and surprising ride comfort. Even better was that since engineers were paid based on the weight of their locomotives, Big Boy engineers enjoyed better pay, too.

Unfortunately, the Big Boy also came at the peak of steam power, right before its fall. Diesel-electric locomotives eventually caught up. Toss in rising costs of coal and labor after World War II and the railroads just found it unfashionable and too expensive to keep the steamers running. The last Big Boy ran revenue service on July 21, 1959. As I said earlier, some of the eventual replacements for the Big Boys included diesel-electrics and the infamous bird-cooking GTELs.

Seeing No. 4014

Steam engines may no longer be in vogue, but Union Pacific is proud to keep a heritage fleet of vintage locomotives running, including two steamers (of which Big Boy No.4014 is one). This locomotive now lives an easier life of touring America, captivating citizens from toddlers to the elderly.

The Big Boy’s display stop in Rochelle was just one of three, and it gave railfans and the general public a chance to see the locomotive up close, talk with UP employees working in the railroad’s steam program, and see something they’ve never seen before.

Rochelle was an hour and a half drive for Sheryl and me, and honestly, I expected maybe a bunch of railfans and that was about it. The reality could not have been further from my expectations.

We arrived in Rochelle at 10 am, or just an hour after the locomotive’s display opened. Despite that, we were stopped cold in our tracks two miles from the intermodal terminal where the Big Boy was parked. Traffic was snarled in every direction and barely moved at all. Traffic moved so slowly that people had time to leave their vehicles, use the bathroom at a gas station, and come back to roughly the same spot in line. Traffic moved so slowly that I had plenty of time to do some car spotting. Look, a Dodge Dakota convertible!

The traffic got so bad that a number of people just abandoned their cars wherever they thought they could legally fit them and you saw entire families marching through grass to get to the terminal. Thankfully, the weather was a cool and breezy yet sunny 65 degrees so it was a great time for a walk.

Sheryl and I finally reached the Big Boy at around 12:30, meaning we traveled at an average speed that was less than 1 mph for the final 2 miles. Why? Well, to my surprise, the Big Boy gathered everyone from all walks of life. A place like the Illinois Railway Museum tends to attract train fans and kids. The Big Boy? It attracted literally everyone, and I loved that. I had no idea so many people would be interested in seeing a vintage train, but I was so happy they did.

I met up with some new Chicago area railfan friends and they taught me a few things along the way.

Attached to the back of the Big Boy were two auxiliary tenders, which is necessary since today’s rail infrastructure isn’t exactly built around steam engines anymore. Behind them is a diesel-electric locomotive, in this case, an EMD SD70. I’m told this locomotive isn’t really helping the Big Boy along because it’s perfectly capable of handling this load. Instead, it’s really there to provide dynamic braking as well as hotel power for the coach cars. Those dynamic brakes, which use the electric motors for slowing rather than friction brakes, allow the Big Boy to slow down without applying the air brakes and wearing down the steamer’s scarce brake pads.

However, there are times when that diesel-electric locomotive is in Notch 1 or Notch 2 power and doing a little bit of the pulling. The logistics of running a steam tour like Union Pacific’s are incredible. Remember, there aren’t water towers for steam engines anymore and even getting the fuel oil is difficult. The Big Boy is a steamer living in a diesel world. So, there are stretches of the tour where the Big Boy may need to run a greater distance between refueling stops than its water and oil reserves can support. That’s when the diesel may run. Again, the Big Boy has more than enough power to haul this small train without breaking a sweat, but this is the reality of a steam train running down a main line in the year 2024.

Despite that, the Big Boy itself isn’t entirely stuck in the past. It has been converted to run on No. 5 fuel oil rather than coal and UP has cleverly integrated positive train control into the locomotive.

Seeing the Big Boy in person is something else. The Big Boy is so large and so long that it makes a diesel locomotive look like a toy. The Big Boy is so huge that its crew is dwarfed by the machine. Yet, unlike the other 7 Big Boys you can see in America and unlike the locomotives at so many museums, your mind is blown by the fact that the Big Boy is a real operational locomotive. This locomotive is something that stops you in your tracks as your mind attempts to process the fact that somehow, this is a man-made object that somehow works.

Seeing the Big Boy, learning more about it, and watching it enchant people from all over made the whole trip worth it. We came from an hour and a half away, yet we saw license plates from places like Minnesota, Ohio, New York, and even as far north as Canada.

If you’re interested in seeing the Big Boy, its next display stop is Houston, Texas on October 6. Then, it’ll stop one more time for two days in Fort Worth, Texas on October 10. Today, the train tour makes a whistle stop at the Amtrak station in Poplar Bluff, Missouri. Tomorrow, the train will leave Poplar Bluff at 9 a.m. bound for Piggott, Arkansas, and Jonesboro, Arkansas. Check UP’s steam schedule to learn more.

So, there’s still plenty of time to see this marvel of engineering. Viewing is free and no matter where you live in America, I highly recommend seeing the Big Boy before this year’s tour is over. Steam may be obsolete, but the Big Boy still has a form of romance you won’t find anywhere else.