From Steam to Green: The Evolution of the Locomotive

A look at freight rail locomotives over time

1868 UP 119

Locomotives have come a long way since their inception. See how they've evolved from early models (like this 1868 American Type) to the green powerhouses they are today.

On February 21, 1804, British mining engineer, inventor and explorer Richard Trevithick debuted the first full-scale working railway steam locomotive in the Welsh mining town of Merthyr Tydfil. Following that debut, locomotives have been powered by a myriad of fuels, including wood, coal and oil. Then, in 1913, diesel powered locomotives hit the scene in Sweden, followed by the U.S. in 1939 and continue to dominate the landscape today.

Locomotives have evolved a great deal since their inception, becoming much more efficient and environmentally friendly over time. Let’s take a look back at Union Pacific’s history of locomotive use to see how they have developed into today’s green powerhouses that can move one ton of freight 480 miles on a single gallon of fuel.

1868 - CP No. 60 and UP No. 119 - American Type

1868 Jupiter

The most popular wheel arrangement in 19th century America, the American Type locomotives were suited to all types of railroad service, including both passenger and freight. These two locomotives — Central Pacific’s “Jupiter” (pictured above) and Union Pacific’s No. 119 (pictured at the top of the page) — are critical to railroad history. When they met at Promontory Summit, Utah, on May 10, 1869, the dream of a transcontinental railroad became a reality.

UP No. 119 - American Type
Length: 41’ 10”
Weight: 68,400 lbs
Fuel: Coal

CP No. 60 - American Type
Length: 41’ 02”
Weight: 65,400 lbs
Fuel: Wood

1905 - SP No. 4151 - Cab Forward – AC-7

1905 UP4151

With a unique wheel arrangement specific to Southern Pacific, these massive, articulated locomotives were designed for greater power and efficiency over the steep mountain passes in the Sierra Nevada. Also unique to Southern Pacific design, these locomotives continued the innovative “cab forward” configuration, putting the engine crew ahead of steam exhaust through miles of tunnels and snow sheds.

Length: 106’
Weight: 639,800 lbs
Fuel: Bunker C Fuel Oil

1941 - UP No. 4014 - Big Boy

1941 UP 4014

The largest and heaviest steam power ever developed, these locomotives were intended to be named the “Wasatch” class of locomotives for their intended area of operation on Union Pacific lines through Wyoming. Instead, the iconic “Big Boys” were named by an employee at the American Locomotive Company (ALCO) who wrote “Big Boy” in chalk on the front of the boiler, and the name stuck. After a lengthy restoration process, Union Pacific Big Boy No. 4014 returned to service in May 2019 to celebrate the 150th Anniversary of the Transcontinental Railroad's Completion.

Length: 132’ 9 7/8”
Weight: 1,189,500 lbs
Fuel: Coal and later, Oil

1944 - UP 844 - Northern

1944 No844

Hailed as Union Pacific’s “Living Legend,” steam locomotive No. 844 was the last steam locomotive built for Union Pacific. A high-speed passenger engine, it pulled such widely known trains as the Overland Limited, Los Angeles Limited, Portland Rose and the Challenger.

Length: 114’
Weight: 907,980 lbs
Fuel: Coal and later, Oil

1955 - UP No. 951 - E-9 Streamliner

1955 UP 951

Representative of Union Pacific’s iconic luxury streamliner train service, locomotives like UP No. 951 pulled the beautiful “City” trains offered by Union Pacific during the heyday of passenger service. Maximum speed for these fast trains was 117 mph.

Length: 70’ 03”
Weight: 315,000 lbs
Fuel: Diesel

1958 -UP X-1 - Super Turbine/“Big Blow”

1958 X-1

Considered the “World’s Most Powerful Locomotive,” the Super Turbines had a comibed horsepower of 8500 and a maximum speed of 65 mph.

Length: 178’ 11”
Weight: 849,248
Fuel: Gas/Electric

2016 - UP 3012 - SD70-AH-16

2016 UP 3012

Tier 4s are 200+ ton road locomotives equipped with Positive Train Control and capable of processing a billion data points per second, maximizing operational and fuel efficiency. Units boast 15 million lines of computer code, five times what a comparable locomotive would have installed five years earlier. These locomotives comply with the very latest emissions standards and reduce emissions by 90 percent compared to locomotives manufactured before the year 2000.

Length: 76’ 8”
Weight: 428,000 lbs
Fuel: Diesel

A Greener Way to Ship

Locomotives have come a long way since they first hit the rails. Thanks in part to their efficient, environmentally friendly operation, today railroads provide the safest, most fuel efficient and environmentally responsible mode of ground freight transportation.

Compare trains to trucks, for instance. On average, trains are three to four times more fuel efficient. What does that mean? On average, U.S. freight railroads can move one ton of freight more than 480 miles on a single gallon of fuel, generating a carbon footprint that is 75 percent less than trucks.

And here’s a fun fact: According to the Association of American Railroads, if just 10 percent of freight now moving by truck moved by rail instead, our country would save about 1.5 billion gallons of fuel annually and annual greenhouse gas emissions would fall by 17 million tons. That’s equivalent to planting about 400 million trees or removing 3.2 million cars from highways for a year.

So here’s a shout-out to Union Pacific customers, who reduced an estimated 31 million metric tons of GHG emissions last year by choosing rail over truck transportation for their shipping needs. Want to learn what impact you could make if your shipment traveled by rail? Check out this Carbon Emission Calculator. Or, get in touch.

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