Union Pacific 4014

{{Infobox locomotive

| name = Union Pacific "Big Boy" 4014

| bgcolor = 000000

| color = FFFFFF

| powertype = Steam

| image = UP 4014 Norden Donner Pass.jpg

| alt = An articulated steam locomotive with a 4-8-8-4 wheel arrangement (four leading wheels, two separate sets of eight driving wheels, and four trailing wheels) and its tender

| caption = Union Pacific No. 4014 charges towards the Norden snow shed at Donner Pass on July 14, 2024

| designer = Otto Jabelmann

| builder = American Locomotive Company {{small|(Schenectady Works)}}

| ordernumber =

| serialnumber = 69585

| buildmodel =

| builddate = November 1941

| rebuilddate =

| totalproduction =

| rebuilder =

| numberrebuilt =

| whytetype = 4-8-8-4

| uicclass = (2′D)D2′ h4

| gauge = {{RailGauge|ussg|allk=on}}

| leadingdiameter = {{convert|36|in|mm|0|abbr=on}}

| driverdiameter = {{convert|68|in|mm|0|abbr=on}}

| trailingdiameter = {{convert|42|in|mm|0|abbr=on}}

| minimumcurve = {{convert|288|ft|m|0|abbr=on}} radius/ 20°

| wheelbase = {{ubl | Locomotive: {{convert|72|ft|5+1/2|in|m|2|abbr=on}} | Overall: {{convert|117|ft|7|in|m|2|abbr=on}} }}

| length = {{ubl | Locomotive: {{convert|85|ft|7.8|in|m|2|abbr=on}} | Overall: {{convert|132|ft|9+7/8|in|m|2|abbr=on}} }}

| width = {{convert|11|ft|2|abbr=on}}

| height = {{convert|16|ft|2+1/2|in|2|abbr=on}}

| axleload = {{convert|68,150|lb|0|abbr=on}}

| weightondrivers = {{convert|545,200|lb|ST|abbr=on}}

| locoweight = {{convert|772,250|lb|ST|abbr=on}}

| tenderweight = {{convert|441,500|lb|ST|abbr=on}}

| locotenderweight = {{convert|1,214,000|lb|ST|abbr=on}}

| tendertype = 25-C

| fueltype = No. 5 fuel oil, originally coal

| fuelcap = Total: {{Convert|6,500|usgal|L|abbr=on}}
Usable: {{Convert|6,100|usgal|L|abbr=on}}

| watercap = {{Convert|25,000|usgal|L|abbr=on}}

| consumption = {{convert|20|-|25|usgal|L|abbr=on}} of fuel oil per mile
{{convert|200|usgal|L|abbr=on}} of water per mile

| tendercap =

| sandcap = {{convert|8,000|lb|short ton|0|abbr= on}}

| boiler = Fire Tube

| boilertype =

| pitch =

| diameterinside = {{convert|107|in|0|abbr=on}}

| lengthinside = {{convert|22|ft|m|0|abbr=on}}

| boilerpressure = {{convert|300|lb/in2|MPa|abbr=on}}

| feedwaterheater = Elesco Type T.P. 502 Exhaust Steam Injector
14,000 US gal / hour capacity

| firearea = 150 sq ft (grate removed in 2019)

| tubearea = {{convert|967|sqft|m2|0|abbr=on}}

| fluearea = {{convert|4,218|sqft|m2|0|abbr=on}}

| tubesandflues = {{convert|5,185|sqft|m2|0|abbr=on}}

| fireboxarea = {{convert|704|sqft|m2|0|abbr=on}}

| totalsurface = {{convert|5,889|sqft|m2|0|abbr=on}}

| superheatertype = Type E

| superheaterarea = {{convert|2,466|sqft|m2|0|abbr=on}}

| cylindercount = Four, outside

| cylindersize = {{convert|24|x|32|in|mm|0|abbr=on}}

| valvegear = Walschaerts

| valvetype = Piston valves

| valvetravel = {{convert|7|in|mm|0|abbr=on}}

| valvelap = {{convert|1+3/8|in|mm|0|abbr=on}}

| valvelead = {{convert|1/4|in|mm|0|abbr=on}}

| maxspeed = {{convert|65|mph|km/h|abbr=on}} in regular service
{{convert|80|mph|km/h|abbr=on}} (maximum design)

| poweroutput = {{convert|8,157|hp|abbr=on}} @ Cylinder
{{convert|6,290 - 7,000|hp|abbr=on}} @ Drawbar

| tractiveeffort = {{convert|138,240|lbf|kN|1|abbr=on}}

| factorofadhesion = 4.00

| trainheating = Steam heat

| locobrakes = Pneumatic, Schedule 8-ET

| locobrakeforce =

| trainbrakes = Pneumatic

| safety = Cab signals, PTC

| operator = Union Pacific Railroad

| operatorclass = 4884-1{{Cite book|last=Drury|first=George H.|year=2015|title=Guide to North American Steam Locomotives|edition=2nd|page=319|publisher=Kalmbach Media|isbn=978-1-62700-259-2}}

| powerclass =

| numinclass = 15

| fleetnumbers = {{ubl|UP 4014}}

| nicknames = Big Boy

| axleloadclass =

| locale = Western United States

| deliverydate = December 1941

| firstrundate = December 1941 (revenue service)
May 2019 (excursion service)

| lastrundate = July 21, 1959

| retiredate = December 7, 1961

| restoredate = May 1, 2019

| withdrawndate =

| preservedunits =

| scrapdate =

| currentowner = Union Pacific
(Union Pacific Heritage Fleet)

| disposition = Operational

| notes = References:{{Cite magazine | date=August 2014| title=Union Pacific No. 4014| url=http://railgiants.org/docs/UP-4014-Information.pdf| magazine=RailGiants Train Museum| publisher=Railway & Locomotive Historical Society, Southern California Chapter| access-date=April 30, 2019| archive-url=https://web.archive.org/web/20160730012718/http://railgiants.org/docs/UP-4014-Information.pdf| archive-date=July 30, 2016}}{{Cite press release | title=Big Boy No. 4014| url=https://www.uprr.com/newsinfo/attachments/media_kit/steam/4014_factsheet.pdf| publisher=Union Pacific| access-date=May 4, 2019| archive-url=https://web.archive.org/web/20160830102645/https://www.uprr.com/newsinfo/attachments/media_kit/steam/4014_factsheet.pdf|archive-date=August 30, 2016}}{{cite book|title=1950–52 Locomotive Cyclopedia of American Practice|year=1950 |url=https://books.google.com/books?id=KDpMAAAAMAAJ|editor=C. B. Peck|publisher=Simmons-Boardman|location=New York|pages=522–523}}

}}

Union Pacific 4014 is a preserved 4884-1 class 4-8-8-4 "Big Boy" type steam locomotive owned and operated by the Union Pacific (UP) as part of its heritage fleet. Built in November 1941 by American Locomotive Company (ALCO) in Schenectady, New York, it was assigned to haul heavy freight trains in the Wasatch mountain range. The locomotive was retired from revenue service on December 7, 1961, and was donated to the Railway & Locomotive Historical Society; thereafter, it was displayed in Fairplex at the RailGiants Train Museum in Pomona, California.

In 2013, UP re-acquired the locomotive and launched a restoration project at its Steam Shop in Cheyenne, Wyoming. In May 2019, No. 4014 moved under its own power after sitting dormant for almost six decades, becoming the world's largest operational steam locomotive and the only operating Big Boy locomotive of the eight that remain in existence. It now operates in excursion service for the UP steam program. No. 4014 became the first mainline steam locomotive to be equipped with the positive train control (PTC) system in 2021.

History

=Design=

The Big Boy class was developed by Union Pacific and built by American Locomotive Company (ALCO) in the 1940s to handle the 1.14% eastbound ruling grade of Utah's Wasatch Range.{{Cite web|last=Glischinski|first=Steve|date=August 21, 2013|title=Big Boy story began in 1940|url=https://www.trains.com/trn/railroads/locomotives/big-boy-story-began-in-1940/|work=Trains|publisher=Kalmbach Media|access-date=October 9, 2022|archive-url=https://web.archive.org/web/20211025165531/https://www.trains.com/trn/railroads/locomotives/big-boy-story-began-in-1940/|archive-date=October 25, 2021}} A team led by UP's chief mechanical officer Otto Jabelmann adapted the design of the 4-6-6-4 Challenger, enlarging the firebox to about {{convert|235|x|96|in|m|2}} (about {{convert|155|sqft|m2|abbr=on|disp=or}}), lengthening the boiler, adding four driving wheels, and reducing the diameter of the driving wheels from {{convert|69|to|68|in|mm|0|abbr=on}}. The locomotives were equipped with a Hancock long-bell 3-chime whistle.{{cite web |title=Hancock Long-Bell 3-Chime Whistle Recordings — Union Pacific Historical Society |url=https://uphs.org/the-streamliner/streamliner-extra/hancock-long-bell-3-chime-whistle-recordings/ |website=uphs.org |access-date=December 13, 2024 |archive-url=https://web.archive.org/web/20240630081524/https://uphs.org/the-streamliner/streamliner-extra/hancock-long-bell-3-chime-whistle-recordings/ |archive-date=June 30, 2024}}

The Big Boy was articulated like the Mallet locomotive design, although without compounding.{{Cite book | last=Morrison| first=Tom| year=2019| title=The American Steam Locomotive in the Twentieth Century| edition=1st| pages=533–534| publisher=McFarland & Company| isbn=978-1-4766-6582-5}} It was designed for stability at {{convert|80|mph|km/h|-1}}, allowing for a wide margin of reliability and safety, as steam locomotives normally operated well below that speed in freight service.{{Cite web | url=https://www.railwayage.com/freight/class-i/up-a-return-to-steam-for-big-boy-4014/| title=UP: A return to steam for Big Boy 4014| last=Vantuono| first=William C.| date=July 28, 2013| work=Railway Age| publisher=Simmons-Boardman Publishing| archive-url=https://web.archive.org/web/20190428230253/https://www.railwayage.com/freight/class-i/up-a-return-to-steam-for-big-boy-4014/| archive-date=April 28, 2019| access-date=April 28, 2019}} Peak power was reached around {{convert|35|mph|km/h|abbr=on}}; optimal tractive effort was maintained up to around {{convert|10|mph|km/h|abbr=on}}. It is longer than two city buses and weighs more than a Boeing 747.{{Cite news|last=Gruver|first=Mead|date=May 8, 2019|url=https://www.usatoday.com/story/travel/news/2019/05/08/union-pacific-big-boy-locomotive-refurbished-transcontinental-railroad-anniversary/1139662001/|title=Refurbished 'Big Boy' locomotive weighs more than a Boeing 747|agency=Associated Press|work=USA Today| archive-url=https://web.archive.org/web/20190608022753/https://www.usatoday.com/story/travel/news/2019/05/08/union-pacific-big-boy-locomotive-refurbished-transcontinental-railroad-anniversary/1139662001/|archive-date=June 8, 2019|access-date=June 12, 2019}}

=Revenue service and retirement=

ALCO built No. 4014 in November 1941 at a cost of $265,174 (${{formatnum:{{Inflation|US|265174|1941|r=-3}}}} in {{inflation year|US}}{{Inflation-fn|US}}) and delivered it the following month to Union Pacific, which placed it in revenue service. No. 4014 was part of the first group of 20 Big Boys, called 4884–1. Designed to haul {{convert|3,600|ST|LT t|0|adj=on}} freight trains over the Wasatch Range, the Big Boys routinely pulled freight trains of up to {{cvt|4,200|ST|LT t|0}}. During a test on April 2, 1943, No. 4014 pulled 65 freight cars between Ogden, Utah, and Evanston, Wyoming, generating a maximum of {{convert|5,530|hp|abbr=on}}.{{Cite book|last=Huddleston|first=Eugene L.|year=2001|title=World's Greatest Steam Locomotives: C&O 2-6-6-6, Virginian 2-6-6-6, N&W 2-6-6-4, UP 4-8-8-4|edition=1st|pages=71–73|publisher=TLC Publishing|isbn=1-883089-60-3|url-access=registration|url=https://archive.org/details/worldsgreatestst0000hudd}}

No. 4014's last routine repairs took place in 1956.{{Cite web | title=Big Wheels Not Yet Turnin'| url=https://www.up.com/aboutup/community/community_ties/0815_4014.htm| work=Community Ties| publisher=Union Pacific| date=August 15, 2013| access-date=May 5, 2019| archive-url=https://web.archive.org/web/20171210071938/https://www.up.com/aboutup/community/community_ties/0815_4014.htm| archive-date=December 10, 2017}} The locomotive completed its final revenue run on July 21, 1959, just hours before the last revenue run by any Big Boy. It had traveled {{convert|1,031,205|mi|km}} during its revenue service. Union Pacific retired No. 4014 on December 7, 1961. All of the remaining Big Boys were retired by 1962, when their duties were taken over by diesel locomotives and gas turbine-electric locomotives (GTELs).{{Cite book | last=Klein| first=Maury| year=2006| title=Union Pacific: Volume II, 1894-1969| edition=2nd| page=479| publisher=University of Minnesota Press| isbn=978-0-8166-4460-5}} That same year, Union Pacific donated No. 4014 to the Southern California chapter of the Railway & Locomotive Historical Society in Pomona, California, where it became one of the eight Big Boys preserved around the United States.{{Cite web|last=Wrinn|first=Jim|date=February 15, 2018|title=Where to find Big Boy locomotives|url=https://trn.trains.com/railroads/railroad-history/2018/02/where-to-find-famous-locomotives|work=Trains|publisher=Kalmbach Media|access-date=June 12, 2019|archive-url=https://web.archive.org/web/20180928212013/https://trn.trains.com/railroads/railroad-history/2018/02/where-to-find-famous-locomotives|archive-date=September 28, 2018}}

=Ownership transfer and restoration=

{{Quote box

| quote = "No other railroad has retained its historical equipment or honored its American roots like Union Pacific. Our steam locomotive program is a source of great pride to UP employees past and present. We are very excited about the opportunity to bring history to life by restoring No. 4014."

| source = —Ed Dickens

| align = left

| width = 250px

| salign =

}}

In late 2012, Union Pacific officials announced that they intended to obtain a Big Boy locomotive for restoration to operational condition for excursion service.{{Cite web | title=Union Pacific studying Big Boy restoration project| url=https://www.trains.com/trn/news-reviews/news-wire/union-pacific-looking-to-restore-big-boy-for-excursion-service/| work=Trains| publisher=Kalmbach Media| date=December 7, 2012| access-date=July 10, 2023| archive-url=https://web.archive.org/web/20230710222036/https://www.trains.com/trn/news-reviews/news-wire/union-pacific-looking-to-restore-big-boy-for-excursion-service/| archive-date=July 10, 2023}} On July 23, 2013, UP announced that the Southern California Chapter of the Railway & Locomotive Historical Society (R&LHS) had agreed to return No. 4014 to UP.{{Cite press release | title=Union Pacific Railroad Acquires Big Boy Locomotive No. 4014| url=https://www.uprr.com/newsinfo/releases/heritage_and_steam/2013/0723_4014.shtml| publisher=Union Pacific| date=July 23, 2013| access-date=April 30, 2019| archive-url=https://web.archive.org/web/20180624110355/https://www.uprr.com/newsinfo/releases/heritage_and_steam/2013/0723_4014.shtml| archive-date=June 24, 2018}}{{efn|On February 22, 2014, UP EMD SD40-2C No. 3105 (née Missouri Pacific No. 6027), UP insulated boxcar No. 453665, and bay window caboose UP No. 24567 (née Rock Island No. 17149) took No. 4014's place in the museum.{{Cite web | title=Union Pacific SD40-2C No. 3105| url=http://www.railgiants.org/UP-3105.htm|work=RailGiants Train Museum| access-date=April 28, 2019| archive-url=https://web.archive.org/web/20190427143418/http://www.railgiants.org/UP-3105.htm| archive-date=April 27, 2019}}{{Cite web | title=UP No. 3105 Heads Home to RailGiants Museum| url=https://www.up.com/aboutup/community/community_ties/0221_3105_railgiants.htm| work=Community Ties| publisher=Union Pacific| date=February 21, 2014| access-date=May 1, 2019| archive-url=https://web.archive.org/web/20160802010146/https://www.up.com/aboutup/community/community_ties/0221_3105_railgiants.htm| archive-date=August 2, 2016}}}}

On November 14, 2013, No. 4014 began its journey to the UP Steam Shop in Cheyenne.{{Cite web | date=November 14, 2013| title=Big Boy No. 4014 Prepares to Leave Pomona| url=https://www.up.com/aboutup/community/community_ties/1114_4014update.htm| work=Community Ties| publisher=Union Pacific| access-date=May 5, 2019| archive-url=https://web.archive.org/web/20170530021727/http://www.up.com/aboutup/community/community_ties/1114_4014update.htm| archive-date=May 30, 2017}}{{Cite news | last=Allen| first=David| date=November 14, 2013| title=Big Boy lumbers to life at Pomona fairgrounds| url=https://www.dailybulletin.com/2013/11/14/big-boy-lumbers-to-life-at-pomona-fairgrounds/| work=Inland Valley Daily Bulletin| access-date=June 7, 2019| archive-url=https://web.archive.org/web/20190607162532/https://www.dailybulletin.com/2013/11/14/big-boy-lumbers-to-life-at-pomona-fairgrounds/| archive-date=June 7, 2019}} It was pulled from its display site at the museum, on temporary track, through the adjacent parking lot. On January 26, 2014, No. 4014 was pulled from the Los Angeles County Fairplex to the Covina station on Metrolink trackage by No. 1996, an SD70ACe diesel locomotive painted in Southern Pacific colors.{{Cite news|last=Day|first=Brian|date=January 26, 2014|title=Gigantic, 73-year-old steam locomotive pays visit to Covina|url=https://www.sgvtribune.com/2014/01/26/gigantic-73-year-old-steam-locomotive-pays-visit-to-covina/|newspaper=San Gabriel Valley Tribune|access-date=July 21, 2023|archive-url=https://web.archive.org/web/20221219151901/https://www.sgvtribune.com/2014/01/26/gigantic-73-year-old-steam-locomotive-pays-visit-to-covina/|archive-date=December 19, 2022}}{{Cite web|url=https://www.up.com/aboutup/community/community_ties/0127_4014_colton.htm|title=Fans Welcome Big Boy No. 4014's Return to the National Rail Network|date=January 27, 2014|work=Community Ties|publisher=Union Pacific|archive-url=https://web.archive.org/web/20190501225334/https://www.up.com/aboutup/community/community_ties/0127_4014_colton.htm|archive-date=May 1, 2019|access-date=May 14, 2019}} It presently arrived at UP's West Colton Yard in Bloomington, California,{{Cite press release | title=West Colton Yard| url=https://www.up.com/cs/groups/public/@uprr/@newsinfo/documents/up_pdf_nativedocs/pdf_up_facilities_west_colton.pdf| work=Union Pacific| access-date=June 6, 2019| archive-url=https://web.archive.org/web/20190606112457/https://www.up.com/cs/groups/public/@uprr/@newsinfo/documents/up_pdf_nativedocs/pdf_up_facilities_west_colton.pdf|archive-date=June 6, 2019}} where it sat on display until April 28, when it began its journey to Cheyenne.{{Cite news |last=Forgione |first=Mary |date=April 28, 2014 |title=Big Boy's wheels to roll Monday on epic California-Wyoming journey |work=Los Angeles Times |url=https://www.latimes.com/travel/deals/la-trb-california-big-boy-steam-engine-20140425-story.html |access-date=April 30, 2019 |archive-url=https://web.archive.org/web/20160909221130/https://www.latimes.com/travel/deals/la-trb-california-big-boy-steam-engine-20140425-story.html |archive-date=September 9, 2016}} After arriving at the Steam Shop's roundhouse on May 8,{{Cite news | last=Rader| first=Anna| date=May 8, 2014| title=Union Pacific Big Boy 4014 Arrives In Cheyenne| url=https://www.wyomingpublicmedia.org/post/union-pacific-big-boy-4014-arrives-cheyenne| publisher=Wyoming Public Radio| access-date=April 30, 2019| archive-url=https://web.archive.org/web/20151001143412/https://www.wyomingpublicmedia.org/post/union-pacific-big-boy-4014-arrives-cheyenne| archive-date=October 1, 2015}} No. 4014 sat largely idle for two years while the UP steam crew worked to overhaul No. 844.{{Cite web | title="Living Legend" Northern No. 844| url=https://www.up.com/heritage/steam/844/| publisher=Union Pacific| access-date=May 3, 2019| archive-url=https://web.archive.org/web/20190421104610/https://www.up.com/heritage/steam/844/| archive-date=April 21, 2019}}{{Cite news|last=Fike|first=Ellen|date=August 20, 2017|title=Big Boy 4014 restoration still set for completion in 2019|url=https://www.wyomingnews.com/big-boy-restoration-still-set-for-completion-in/article_f0f3385e-8435-11e7-8d52-43f95323c973.html|work=Wyoming Tribune Eagle|access-date=June 7, 2019|archive-url=https://web.archive.org/web/20190114103435/https://www.wyomingnews.com/big-boy-restoration-still-set-for-completion-in/article_f0f3385e-8435-11e7-8d52-43f95323c973.html|archive-date=January 14, 2019}} The Steam Shop also used the time to expand and upgrade its facilities to accommodate a Big Boy.{{Cite news|date=November 24, 2014|title=Work on Big Boy locomotive goes slowly|url=https://www.omaha.com/money/work-on-big-boy-locomotive-goes-slowly/article_5fa52cc2-c00a-5103-9eb2-c102eee287bc.html|work=Omaha World-Herald|agency=Associated Press|access-date=July 1, 2019|archive-url=https://web.archive.org/web/20190701133854/https://www.omaha.com/money/work-on-big-boy-locomotive-goes-slowly/article_5fa52cc2-c00a-5103-9eb2-c102eee287bc.html|archive-date=July 1, 2019}}

In August 2016, a month after No. 844's repairs and inspection were complete, UP officials announced that the restoration work of No. 4014 had begun under Heritage Fleet Operations director Ed Dickens.{{Cite web | url=https://www.up.com/aboutup/community/inside_track/august-steam-8-11-2016.htm| title=Steam Update: Big Boy No. 4014 Restoration Begins| date=August 11, 2016| work=Inside Track| publisher=Union Pacific| archive-url=https://web.archive.org/web/20180806172345/https://www.up.com/aboutup/community/inside_track/august-steam-8-11-2016.htm| archive-date=August 6, 2018| access-date=April 27, 2019}}{{Cite web | title=Big Boy Work Begins| url=https://trn.trains.com/news/news-wire/2016/08/12-big-boy-work-begins| work=Trains| publisher=Kalmbach Media| date=August 12, 2016| access-date=April 28, 2019| archive-url=https://web.archive.org/web/20180710010212/http://trn.trains.com/news/news-wire/2016/08/12-big-boy-work-begins| archive-date=July 10, 2018}} By early 2017, the locomotive had been completely disassembled.{{Cite web | url=https://www.up.com/aboutup/community/inside_track/steam-update-2-1-2017.htm| title=Steam Update: With Disassembly Complete, Big Boy Fabrication Underway| date=February 1, 2017| work=Inside Track| publisher=Union Pacific| archive-url=https://web.archive.org/web/20170822145223/https://www.up.com/aboutup/community/inside_track/steam-update-2-1-2017.htm| archive-date=August 22, 2017| access-date=August 5, 2019}} Some new parts were fabricated, including the rod brasses, top boiler check valve, and lubricator check valves. The driving wheels were sent to be repaired by the Strasburg Rail Road in Strasburg, Pennsylvania, for crankpin and axle work as well as installing new tires.{{Cite web | title=Progress report on Union Pacific Big Boy 4014| url=https://trn.trains.com/news/news-wire/2018/03/03-progress-report-on-union-pacific-big-boy-4014| work=Trains| publisher=Kalmbach Media| date=March 3, 2018| access-date=May 4, 2019| archive-url=https://web.archive.org/web/20180727091837/http://trn.trains.com/news/news-wire/2018/03/03-progress-report-on-union-pacific-big-boy-4014| archive-date=July 27, 2018}}{{Cite web | title=Union Pacific confirms Big Boy 4-8-8-4 No. 4014 for Ogden in 2019 and more| url=https://trn.trains.com/news/news-wire/2018/05/10-union-pacific-confirms-big-boy-4-8-8-4-no-4014-for-ogden-in-2019-and-more| work=Trains| publisher=Kalmbach Media| date=May 10, 2018| access-date=May 4, 2019| archive-url=https://web.archive.org/web/20181018195409/https://trn.trains.com/news/news-wire/2018/05/10-union-pacific-confirms-big-boy-4-8-8-4-no-4014-for-ogden-in-2019-and-more| archive-date=October 18, 2018}}

The work included one major alteration: converting the coal-burning locomotive to run on No. 5 fuel oil. This was done by replacing the firebox grates with a fire pan and an oil burner.{{Cite web | title=Putting the 'Big Boy' Back Together| url=https://www.up.com/aboutup/community/inside_track/steam-update-03-22-2018.htm| work=Inside Track| publisher=Union Pacific| date=March 22, 2018| access-date=April 27, 2019| archive-url=https://web.archive.org/web/20180917163429/https://www.up.com/aboutup/community/inside_track/steam-update-03-22-2018.htm| archive-date=September 17, 2018}} This made No. 4014 the first Big Boy to undergo a coal-to-oil conversion since No. 4005, which ran on oil from 1946 until it was converted back to coal in 1948 due to uneven heating in its large, single-burner firebox.{{Cite web|last=Frank|first=Al|title=Big Boy|url=https://www.forneymuseum.org/Featured_Exhibit.html|publisher=Forney Museum of Transportation|access-date=July 27, 2019|archive-url=https://web.archive.org/web/20181210052304/https://www.forneymuseum.org/Featured_Exhibit.html|archive-date=December 10, 2018}} No. 4014's old firebox grates were salvaged and used on the Milwaukee Road 261 steam locomotive.{{Cite web | last=Glischinski| first=Steve| date=March 29, 2017| title=Minnesota steam engine to use Big Boy fire grates| url=https://trn.trains.com/news/news-wire/2017/03/29-big-boy-grates| work=Trains| publisher=Kalmbach Media| access-date=August 5, 2019| archive-url=https://web.archive.org/web/20170331030616/https://trn.trains.com/news/news-wire/2017/03/29-big-boy-grates| archive-date=March 31, 2017}}{{efn|No. 261 may be converted to burn oil, depending on the feasibility study and cost-benefit analysis.{{Cite web | last=Glischinski| first=Steve| date=March 11, 2021| title=Study will consider conversion of Milwaukee Road 261 to burn oil| url=https://www.trains.com/trn/news-reviews/news-wire/study-will-consider-conversion-of-milwaukee-road-261-to-burn-oil/| work=Trains| publisher=Kalmbach Media| access-date=July 7, 2023| archive-url=https://web.archive.org/web/20210920111717/https://www.trains.com/trn/news-reviews/news-wire/study-will-consider-conversion-of-milwaukee-road-261-to-burn-oil/| archive-date=September 20, 2021}}}}

In March 2018, it was reported that No. 4014 was being reassembled; ten months later, the locomotive's restoration was nearly finished.{{Cite web | title=Steam Update: Big Boy's Restoration Nearly Complete| url=https://www.up.com/aboutup/community/inside_track/steam-update-1-29-2019.htm| work=Inside Track| publisher=Union Pacific| date=January 29, 2019| access-date=April 27, 2019| archive-url=https://web.archive.org/web/20190427005537/https://www.up.com/aboutup/community/inside_track/steam-update-1-29-2019.htm| archive-date=April 27, 2019}} On February 6, 2019, No. 4014's boiler passed a hydrostatic test and the locomotive was successfully test-fired on April 9.{{Cite web|title='Big Boy' passes early pressure test|url=https://trn.trains.com/news/news-wire/2019/02/06-big-boy-passes-early-pressure-test|work=Trains|publisher=Kalmbach Media|date=February 6, 2019|access-date=June 27, 2019|archive-url=https://web.archive.org/web/20190504022628/http://trn.trains.com/news/news-wire/2019/02/06-big-boy-passes-early-pressure-test|archive-date=May 4, 2019}}{{Cite web|last=Wrinn|first=Jim|title=Big Boy 4014, a hydrostatic test, and why UP can beat the usual six month rule|url=https://cs.trains.com/trn/b/staff/archive/2019/02/08/big-boy-4014-a-hydrostatic-test-and-why-up-can-beat-the-usual-six-month-rule.aspx|work=Trains|publisher=Kalmbach Media|date=February 8, 2019|access-date=May 30, 2019|archive-url=https://web.archive.org/web/20190530220514/http://cs.trains.com/trn/b/staff/archive/2019/02/08/big-boy-4014-a-hydrostatic-test-and-why-up-can-beat-the-usual-six-month-rule.aspx|archive-date=May 30, 2019}}{{Cite web | url=https://trn.trains.com/news/news-wire/2019/04/10-big-boy-no-4014-fired-up-for-the-first-time-may-12-excursion-announced| title=Big Boy No. 4014 fired up for the first time; May 12 excursion announced| date=April 10, 2019| work=Trains| publisher=Kalmbach Media| archive-url=https://web.archive.org/web/20190410195349/http://trn.trains.com/news/news-wire/2019/04/10-big-boy-no-4014-fired-up-for-the-first-time-may-12-excursion-announced| archive-date=April 10, 2019| access-date=April 16, 2019}} Around 9 p.m. on May 1, 2019, No. 4014 moved under its own power for the first time in almost 60 years.{{Cite web | last=Wrinn| first=Jim| title=Under its own power, Big Boy moves outside of shop| url=https://trn.trains.com/news/news-wire/2019/05/02-big-boy-moves-outside-of-shop| work=Trains| publisher=Kalmbach Media| date=May 2, 2019| access-date=May 2, 2019| archive-url=https://web.archive.org/web/20190502201255/http://trn.trains.com/news/news-wire/2019/05/02-big-boy-moves-outside-of-shop| archive-date=May 2, 2019}} Its tender, No. 25-C-311, originally belonged to UP Challenger No. 3985, another locomotive in UP's steam program.{{Cite web |last=Wrinn |first=Jim |date=March 31, 2020 |title=Union Pacific No. 3985's next stop |url=https://cs.trains.com/trn/b/staff/archive/2020/03/31/union-pacific-no-3985-39-s-next-stop.aspx |archive-url=https://web.archive.org/web/20210117041006/http://cs.trains.com/trn/b/staff/archive/2020/03/31/union-pacific-no-3985-39-s-next-stop.aspx |archive-date=January 17, 2021 |access-date=June 23, 2021 |work=Trains |publisher=Kalmbach Media}}{{Cite book |last=Wrinn |first=Jim |title=Union Pacific's Big Boys: The Complete Story from History to Restoration |publisher=Kalmbach Media |year=2020 |isbn=978-1-62700-792-4 |edition=1st |page=143}} The following evening, the locomotive made its first test run, from Cheyenne to Nunn, Colorado.{{Cite web | last=Wrinn| first=Jim| title=Big Boy debuts with test run| url=https://trn.trains.com/news/news-wire/2019/05/03-big-boy-debuts-with-test-run| work=Trains| publisher=Kalmbach Media| date=May 3, 2019| access-date=May 3, 2019| archive-url=https://web.archive.org/web/20190503172951/http://trn.trains.com/news/news-wire/2019/05/03-big-boy-debuts-with-test-run| archive-date=May 3, 2019}} One estimate put the cost of restoration at $4 million or more.{{cite news |last1=Gruver |first1=Mead |title=Massive restored locomotive steaming to Ogden for Thursday Golden Spike gathering |url=https://www.sltrib.com/news/nation-world/2019/05/07/massive-restored/ |access-date=January 8, 2025 |work=The Salt Lake Tribune |date=May 9, 2019 |archive-url=https://web.archive.org/web/20240421085953/https://www.sltrib.com/news/nation-world/2019/05/07/massive-restored/ |archive-date=April 21, 2024}}

=Excursion service=

Once restored, No. 4014 joined the railroad's never-retired Union Pacific FEF series No. 844 steam locomotive in excursion service.{{Cite news|last=Scott|first=Ramsey|date=May 4, 2019|title=The Big Boy leaves the shop and heads into history|url=https://www.wyomingnews.com/news/local_news/the-big-boy-leaves-the-shop-and-heads-into-history/article_4fd7b951-04d4-514e-b464-b9524044ca43.html|work=Wyoming Tribune Eagle|access-date=June 7, 2019|archive-url=https://web.archive.org/web/20190504181523/https://www.wyomingnews.com/news/local_news/the-big-boy-leaves-the-shop-and-heads-into-history/article_4fd7b951-04d4-514e-b464-b9524044ca43.html|archive-date=May 4, 2019}}{{Cite web|last=Sweeney|first=Steve|title=UP steam crew has Big Boy ready to roll|url=https://trn.trains.com/news/news-wire/2019/05/04-big-boy-is-ready-to-roll|work=Trains|publisher=Kalmbach Media|date=May 4, 2019|access-date=July 17, 2019|archive-url=https://web.archive.org/web/20190506022407/http://trn.trains.com/news/news-wire/2019/05/04-big-boy-is-ready-to-roll|archive-date=May 6, 2019}} It also became the world's largest operational steam locomotive, displacing UP No. 3985.{{Cite web|last=Keefe|first=Kevin|date=January 17, 2020|title=The Challenger at high tide|url=https://cs.trains.com/ctr/b/mileposts/archive/2020/01/17/the-challenger-at-high-tide.aspx?|archive-url=https://web.archive.org/web/20210511080452/http://cs.trains.com/ctr/b/mileposts/archive/2020/01/17/the-challenger-at-high-tide.aspx|archive-date=May 11, 2021|access-date=June 23, 2021|work=Classic Trains|publisher=Kalmbach Media}}

In May 2019, No. 4014 made its first excursion run amid the celebrations marking 150 years since the completion of the first transcontinental railroad.{{Cite press release | title=World's Largest Steam Locomotive Returns to the Rails as Union Pacific Commemorates Transcontinental Railroad's 150th Anniversary| url=https://www.up.com/media/releases/190314-big-boy-schedule.htm| publisher=Union Pacific| date=March 14, 2019| access-date=May 2, 2019| archive-url=https://web.archive.org/web/20190502214019/https://www.up.com/media/releases/190314-big-boy-schedule.htm| archive-date=May 2, 2019}}{{Cite web | last=Wrinn| first=Jim| title=Big Boy christened, begins trip to Golden Spike celebration| url=https://trn.trains.com/news/news-wire/2019/05/04-big-boy-christened-leads-doubleheader-to-rawlins-wyo| work=Trains| publisher=Kalmbach Media| date=May 4, 2019| access-date=May 5, 2019| archive-url=https://web.archive.org/web/20190505170122/http://trn.trains.com/news/news-wire/2019/05/04-big-boy-christened-leads-doubleheader-to-rawlins-wyo| archive-date=May 5, 2019}} Following its May 4 christening at the Cheyenne Depot Museum, No. 4014 — doubleheaded with No. 844 — traveled to Ogden, Utah.{{Cite news|last=O'Donoghue|first=Amy|title=Thousands turn out as Big Boy locomotive rolls into Ogden|url=https://www.deseret.com/2019/5/9/20673052/thousands-turn-out-as-big-boy-locomotive-rolls-into-ogden|work=Deseret News|date=May 9, 2019|access-date=May 12, 2019|archive-url=https://web.archive.org/web/20190509231155/https://www.deseretnews.com/article/900069881/thousands-turn-out-as-big-boy-locomotive-rolls-into-ogden.html|archive-date=May 9, 2019}}{{Cite press release|title=Union Pacific Recreates Historic Steam Meet, Commemorating 150th Anniversary of the Transcontinental Railroad's Completion|url=https://www.up.com/media/releases/190509-transcon150.htm|publisher=Union Pacific|date=May 9, 2019|access-date=June 11, 2019| archive-url=https://web.archive.org/web/20190611023659/https://www.up.com/media/releases/190509-transcon150.htm|archive-date=June 11, 2019}} No. 4014 subsequently made two tours on its own.{{Cite press release|title=Union Pacific's Big Boy No. 4014 Locomotive Prepares for 'Great Race Across the Midwest'|url=https://www.up.com/media/releases/190613-big-boy-4014-midwest.htm|publisher=Union Pacific|date=June 13, 2019|access-date=July 8, 2019|archive-url=https://web.archive.org/web/20190708200840/https://www.up.com/media/releases/190613-big-boy-4014-midwest.htm|archive-date=July 8, 2019}}{{Cite press release| title=Union Pacific's Big Boy No. 4014 Locomotive Concludes 150th Anniversary Celebration with 'Great Race Across the Southwest'| url=https://www.up.com/media/releases/190905-big-boy-southwest.htm| publisher=Union Pacific| date=September 5, 2019| access-date=September 28, 2019| archive-url=https://web.archive.org/web/20190906171040/https://www.up.com/media/releases/190905-big-boy-southwest.htm| archive-date=September 6, 2019}} From July 8 to August 8, it visited the Midwestern United States, including brief stops at Saint Paul Union Depot and the Lake Superior Railroad Museum;{{Cite news|last=Obert|first=Elizabeth|date=July 14, 2019|title=Historic locomotive Big Boy No. 4014 rolls into St. Paul|url=https://www.twincities.com/2019/07/14/big-boy-no-4014-historic-steam-locomotive-makes-appearance-in-st-paul/|work=St. Paul Pioneer Press|access-date=November 16, 2022|archive-url=https://web.archive.org/web/20210511131801/https://www.twincities.com/2019/07/14/big-boy-no-4014-historic-steam-locomotive-makes-appearance-in-st-paul/|archive-date=May 11, 2021}}{{Cite web|title=Festival of Steam with Big Boy No. 4014|url=https://lsrm.org/event/festival-steam-big-boy-no-4014/|access-date=March 7, 2021|website=Lake Superior Railroad Museum|archive-url=https://web.archive.org/web/20190726111353/https://lsrm.org/event/festival-steam-big-boy-no-4014/|archive-date=July 26, 2019}} it then toured the Southwestern United States from September 27 to November 26.

In January 2020, Union Pacific officials announced that the UP Steam Team would retire No. 3985, which was in poor mechanical condition. Due to the COVID-19 pandemic, UP announced in March 2020 that it would cancel that year's steam operations.{{Cite news|last=Bodiford|first=Vince|title=Union Pacific Big Boy #4014 steam tour cancelled| url=https://www.thecheyennepost.com/news/union-pacific-big-boy-4014-steam-tour-cancelled/article_25e7dcdc-8a4f-11ea-812e-e3053b995b23.html|work=The Cheyenne Post|date=April 29, 2020|access-date=May 23, 2021|archiveurl=https://web.archive.org/web/20200516215025/https://www.thecheyennepost.com/news/union-pacific-big-boy-4014-steam-tour-cancelled/article_25e7dcdc-8a4f-11ea-812e-e3053b995b23.html|archive-date=May 16, 2020}} Excursion operations resumed in August and September 2021 with No. 4014 doing tour stops in Fort Worth and Houston, Texas; New Orleans, Louisiana; North Little Rock, Arkansas; St. Louis, Missouri; and Denver, Colorado.{{Cite press release|title=Full Steam Ahead: World's Largest Steam Locomotive Returns with 'The Big Boy 2021 Tour'|url=https://www.up.com/media/releases/210614-big-boy-tour.htm|publisher=Union Pacific|date=June 14, 2021|access-date=June 17, 2021|archive-url=https://web.archive.org/web/20210614200842/https://www.up.com/media/releases/210614-big-boy-tour.htm|archive-date=June 14, 2021}}

In May 2022, the Railroading Heritage of Midwest America (RRHMA) in Silvis, Illinois, announced plans to convert No. 4014's original tender, No. 25-C-116, to carry fuel oil instead of coal.{{Cite web|last=Kratville-Wrinn|first=Cate|date=May 13, 2022|title=Original Big Boy tender to be restored by Railroading Heritage of Midwest America|url=https://www.trains.com/trn/news-reviews/news-wire/original-big-boy-tender-to-be-restored-by-railroading-heritage-of-midwest-america/|work=Trains|publisher=Kalmbach Media|access-date=May 16, 2022|archive-url=https://web.archive.org/web/20220513134836/https://www.trains.com/trn/news-reviews/news-wire/original-big-boy-tender-to-be-restored-by-railroading-heritage-of-midwest-america/|archive-date=May 13, 2022}} While the work proceeds, No. 4014 is using the No. 25-C-311 tender, which will eventually be reconnected to the No. 3985 locomotive being donated by UP to the RRHMA.{{Cite press release|title=Union Pacific, Railroading Heritage of Midwest America reach agreement to preserve historic locomotives, passenger cars|url=https://rrhma.com/up-donation/|publisher=Railroading Heritage of Midwest America|access-date=May 2, 2022|archive-url=https://web.archive.org/web/20220428204728/https://rrhma.com/up-donation/|archive-date=April 28, 2022}}{{Cite web|last=Glischinski|first=Steve|date=April 28, 2022|title=Railroading Heritage of Midwest America, Union Pacific agree to donation of Challenger, other locomotives, cars|url=https://www.trains.com/trn/news-reviews/news-wire/railroading-heritage-of-midwest-america-union-pacific-agree-to-donation-of-challenger-other-locomotives-cars/|work=Trains|publisher=Kalmbach Media|access-date=May 2, 2022|archive-url=https://web.archive.org/web/20220428191606/https://www.trains.com/trn/news-reviews/news-wire/railroading-heritage-of-midwest-america-union-pacific-agree-to-donation-of-challenger-other-locomotives-cars/|archive-date=April 28, 2022}} In late July 2022, No. 4014 pulled the Museum Special excursion between Cheyenne and the Denver Union Station to benefit the Union Pacific Railroad Museum.{{Cite web|last=Franz|first=Justin|date=June 30, 2022|title=Union Pacific 'Big Boy' to Visit Denver in July|url=https://railfan.com/union-pacific-big-boy-to-visit-denver-in-july/|work=Railfan & Railroad|publisher=White River Productions|access-date=July 1, 2022|archive-url=https://web.archive.org/web/20220701015103/https://railfan.com/union-pacific-big-boy-to-visit-denver-in-july/|archive-date=July 1, 2022}}{{Cite press release|title=Union Pacific Announces Big Boy No. 4014 July Trip between Denver and Cheyenne|url=https://www.up.com/media/releases/big-boy-denver-nr-220721.htm|publisher=Union Pacific|date=July 21, 2022|access-date=July 29, 2022|archive-url=https://web.archive.org/web/20220721201337/https://www.up.com/media/releases/big-boy-denver-nr-220721.htm|archive-date=July 21, 2022}}{{efn|UP originally announced on April 11, 2022, that No. 4014 would tour the Northwestern United States, starting on June 26 in commemoration of UP's 160th anniversary, but the tour was cancelled on April 22 so UP could reduce supply chain congestion.{{Cite press release|title=World's Largest Steam Locomotive 'Big Boy No. 4014' Returns to the Tracks to Celebrate 160 years of Union Pacific|url=https://www.up.com/media/releases/west-coast-steam-nr-220411.htm|publisher=Union Pacific|date=April 11, 2022|access-date=April 11, 2022|archive-url=https://web.archive.org/web/20220411151646/https://www.up.com/media/releases/west-coast-steam-nr-220411.htm|archive-date=April 11, 2022}}{{Cite press release|title=Union Pacific Postpones Big Boy No. 4014 West Coast Steam Tour|url=https://www.up.com/media/releases/steam-tour-postponed-nr-220422.htm|publisher=Union Pacific|date=April 22, 2022|access-date=April 23, 2022|archive-url=https://web.archive.org/web/20220423000419/https://www.up.com/media/releases/steam-tour-postponed-nr-220422.htm|archive-date=April 23, 2022}}}} On September 14, 2022, No. 4014 was fired up to move Union Pacific 5511 from the Cheyenne roundhouse and around the yard for testing before the 2-10-2 locomotive left for the RRHMA two months later.{{Cite web|date=September 15, 2022|title=Union Pacific Fires Up 'Big Boy' to Move Rare 2-10-2|url=https://railfan.com/union-pacific-fires-up-big-boy-to-move-rare-2-10-2/|work=Railfan & Railroad|publisher=White River Productions|access-date=November 27, 2023|archive-url=https://web.archive.org/web/20230529144753/https://railfan.com/union-pacific-fires-up-big-boy-to-move-rare-2-10-2/|archive-date=May 29, 2023}}{{Cite web|last=Sanchez|first=Cesar|date=November 19, 2022|title=3 of the largest and rarest locomotives arrive in Silvis|url=https://www.wqad.com/article/news/local/union-pacific-heritage-donation-railroading-heritage-of-midwestern-america-silvis-illinois/526-17d95fd9-d6e6-4bee-aa41-b384720297f8|work=WQAD-TV|access-date=May 31, 2024|archive-url=https://web.archive.org/web/20230105043127/https://www.wqad.com/article/news/local/union-pacific-heritage-donation-railroading-heritage-of-midwestern-america-silvis-illinois/526-17d95fd9-d6e6-4bee-aa41-b384720297f8|archive-date=January 5, 2023}}

In June 2023, No. 4014 ran from Cheyenne to Omaha, Nebraska, with the Home Run Express Tour, for display at Charles Schwab Field Omaha on June 15-21 and 24-25.{{Cite web|title=Union Pacific announces Big Boy trip to Omaha|url=https://www.trains.com/trn/news-reviews/news-wire/union-pacific-announces-big-boy-trip-to-omaha/|work=Trains|publisher=Kalmbach Media|date=May 19, 2023|access-date=May 19, 2023|archive-url=https://web.archive.org/web/20230519161710/https://www.trains.com/trn/news-reviews/news-wire/union-pacific-announces-big-boy-trip-to-omaha/|archive-date=May 19, 2023}}{{Cite press release|title=Union Pacific's Historic 'Big Boy No. 4014' Set to Score a Home Run During College World Series|url=https://www.up.com/media/releases/big-boy-omaha-nr-230519.htm|publisher=Union Pacific|date=May 19, 2023|access-date=June 21, 2023|archive-url=https://web.archive.org/web/20230522022836/https://www.up.com/media/releases/big-boy-omaha-nr-230519.htm|archive-date=May 22, 2023}} During the return journey to Cheyenne on June 29, No. 4014 banked a stalled freight train up the grade in Blair, Nebraska.{{cite journal |last1=Johnson |first1=Greg |title=Wyoming's Big Boy 4014 Locomotive Rescues Freight Train Stuck In Nebraska |journal=Cowboy State Daily |date=July 10, 2023 |url=https://cowboystatedaily.com/2023/07/10/wyomings-big-boy-4014-locomotive-rescues-freight-train-stuck-in-nebraska/ |access-date=July 10, 2023 |language=en |archive-url=https://web.archive.org/web/20230710221037/https://cowboystatedaily.com/2023/07/10/wyomings-big-boy-4014-locomotive-rescues-freight-train-stuck-in-nebraska/ |archive-date=July 10, 2023 }} Two cab rides on the July 3 journey from Pine Bluffs, Wyoming, to Cheyenne were sold for $9,500 apiece to benefit the Union Pacific Railroad Museum.{{Cite web|title=UP placing two tickets on sale today for Big Boy cab rides|url=https://www.trains.com/trn/news-reviews/news-wire/up-placing-two-tickets-on-sale-today-for-big-boy-cab-rides/|work=Trains|publisher=Kalmbach Media|date=June 23, 2023|access-date=July 5, 2023|archive-url=https://web.archive.org/web/20230627051149/https://www.trains.com/trn/news-reviews/news-wire/up-placing-two-tickets-on-sale-today-for-big-boy-cab-rides/|archive-date=June 27, 2023}}{{efn|UP's original plan was to auction off one cab ride.{{Cite web|title=UP Museum holds auction for Big Boy cab ride|url=https://www.trains.com/trn/news-reviews/news-wire/up-museum-holds-auction-for-big-boy-cab-ride/|work=Trains|publisher=Kalmbach Media|date=June 5, 2023|access-date=June 27, 2023|archive-url=https://web.archive.org/web/20230605143515/https://www.trains.com/trn/news-reviews/news-wire/up-museum-holds-auction-for-big-boy-cab-ride/|archive-date=June 5, 2023}} But on June 23, UP informed its Steam Club members that the auction "was manipulated by an individual and did not result in an award to the highest bidder" and that as a result, the museum would sell two tickets, priced at $9,500 each, at 5 p.m. CDT on its website.}}

Two tours were executed in 2024.{{Cite web|date=April 10, 2024|title=Union Pacific 'Big Boy' 4014 Heads West in July|url=https://railfan.com/union-pacific-big-boy-4014-heads-west-in-july/|work=Railfan & Railroad|publisher=White River Productions|access-date=April 24, 2024|archive-url=https://web.archive.org/web/20240410230653/https://railfan.com/union-pacific-big-boy-4014-heads-west-in-july/|archive-date=April 10, 2024}} The first ran from June 30 to July 26, with stops at the Western Pacific Railroad Museum in Portola, California, on July 10,{{cite web |title=UP 4014 Celebration - July 2024 |url=https://www.wplives.org/news_items/2024_Union_Pacific_Big_Boy_4014.html |website=www.wplives.org |access-date=July 13, 2024 |archive-url=https://web.archive.org/web/20240705033717/https://www.wplives.org/news_items/2024_Union_Pacific_Big_Boy_4014.html |archive-date=July 5, 2024}} Roseville, California, on July 12 and 13, and Ogden, Utah on July 20 and 21. The second tour began on August 28 and concluded on October 23; it included stops in Texas, Arkansas, Kansas, and Illinois. On the second tour's journey through Iowa in September, American comedian and former The Tonight Show host Jay Leno hitched a ride on No. 4014 to film the episode for his YouTube web series Jay Leno's Garage.{{cite news |last1=Jean |first1=Renée |title=Jay Leno Climbs Aboard Cheyenne’s Big Boy Locomotive For His TV Show |url=https://cowboystatedaily.com/2024/09/17/jay-leno-climbs-aboard-cheyennes-big-boy-locomotive-for-his-tv-show/ |access-date=September 23, 2024 |work=Cowboy State Daily |date=September 17, 2024 |archive-url=https://web.archive.org/web/20240919143304/https://cowboystatedaily.com/2024/09/17/jay-leno-climbs-aboard-cheyennes-big-boy-locomotive-for-his-tv-show/ |archive-date=September 19, 2024 |language=en}}

=Positive train control=

In December 2018, Union Pacific asked the Federal Railroad Administration (FRA) to exempt UP Nos. 4014 and 844 from federal positive train control (PTC) requirements;{{Cite web|date=December 13, 2018|title=Big Boy 4014 gets drivers; UP asks for PTC waivers for three steam locomotives|url=https://trn.trains.com/news/news-wire/2018/12/13-big-boy-4014-gets-drivers-up-asks-for-ptc-waivers-for-three-steam-locomotives|work=Trains|publisher=Kalmbach Media|access-date=June 9, 2019|archive-url=https://web.archive.org/web/20190608214004/http://trn.trains.com/news/news-wire/2018/12/13-big-boy-4014-gets-drivers-up-asks-for-ptc-waivers-for-three-steam-locomotives|archive-date=June 8, 2019}} three months later, the FRA officials responded that such waivers were not needed.{{Cite web|last=Wrinn|first=Jim|date=February 28, 2019|title=FRA: UP doesn't need waiver to run steam 11,000 miles in 2019|url=https://trn.trains.com/news/news-wire/2019/02/28-fra-says-up-doesnt-need-wavier-to-run-steam-11000-miles-in-2019|work=Trains|publisher=Kalmbach Media|access-date=June 9, 2019|archive-url=https://web.archive.org/web/20190609162057/http://trn.trains.com/news/news-wire/2019/02/28-fra-says-up-doesnt-need-wavier-to-run-steam-11000-miles-in-2019|archive-date=June 9, 2019}}

In 2021, No. 4014 became the first mainline steam locomotive to be equipped with PTC.{{Cite web |date=August 19, 2021 |title=Big Boy Flexes Its Muscles with Positive Train Control |url=https://www.up.com/aboutup/community/inside_track/big-boy-ptc-210819.htm |url-status=live |archive-url=https://web.archive.org/web/20210820003243/https://www.up.com/aboutup/community/inside_track/big-boy-ptc-210819.htm |archive-date=August 20, 2021 |access-date=August 20, 2021 |work=Inside Track |publisher=Union Pacific}}{{Cite news |date=August 20, 2021 |title=UP 4014 First Main Line Steam Locomotive Outfitted With PTC |work=Railfan & Railroad |publisher=White River Productions |url=https://railfan.com/up-4014-first-main-line-steam-locomotive-outfitted-with-ptc/ |url-status=live |access-date=October 14, 2022 |archive-url=https://web.archive.org/web/20210820194341/https://railfan.com/up-4014-first-main-line-steam-locomotive-outfitted-with-ptc/ |archive-date=August 20, 2021}} Initially, its PTC display was powered by computers and equipment in its helper diesel locomotive, UP SD70M No. 4015.{{Cite web|date=March 8, 2024|title=Diesel helpers often lend a hand on mainline steam excursions|url=https://www.trains.com/trn/train-basics/abcs-of-railroading/diesel-helpers-often-lend-a-hand-on-mainline-steam-excursions/|work=Trains|publisher=Kalmbach Media|access-date=May 26, 2024|archive-url=https://web.archive.org/web/20240329033152/https://www.trains.com/trn/train-basics/abcs-of-railroading/diesel-helpers-often-lend-a-hand-on-mainline-steam-excursions/|archive-date=March 29, 2024}} In May 2024, PTC equipment was installed in a cabinet in the tender, and a third dynamo added to the locomotive to provide electrical power, allowing No. 4014 to run without a diesel helper.{{Cite news|date=May 23, 2024|title='Big Boy' 4014 Runs on Main Line Solo With New PTC System|url=https://railfan.com/big-boy-4014-runs-on-main-line-solo-with-new-ptc-system/|work=Railfan & Railroad|publisher=White River Productions|access-date=May 26, 2024|archive-url=https://web.archive.org/web/20240525004809/https://railfan.com/big-boy-4014-runs-on-main-line-solo-with-new-ptc-system/|archive-date=May 25, 2024}}

Gallery

File:UP Big Boy 4014.jpg|alt=An articulated steam locomotive on static display|No. 4014 on static display at the RailGiants Train Museum in Pomona, California, in 2005

File:Union Pacific Big Boy 4014 (14052153641).jpg|alt=Two yellow diesel locomotives hauling an articulated steam locomotive, one at the front and the other at the back, through the mountains in the background|UP SD70Ms Nos. 4014 and 4884 haul No. 4014 over Cajon Pass to Cheyenne, Wyoming, for restoration.{{efn|On April 10, 2019, the diesel locomotive numbered 4014 was redesignated as 4479 on the UP active locomotive roster, allowing the "Big Boy" to retain the number.{{Cite web | title=Union Pacific to renumber SD70M No. 4014 before Big Boy runs| url=https://trn.trains.com/news/news-wire/2018/06/27-union-pacific-will-renumber-sd70-4014| work=Trains| publisher=Kalmbach Media|date=June 27, 2018| access-date=April 28, 2019| archive-url=https://web.archive.org/web/20181018191935/http://trn.trains.com/news/news-wire/2018/06/27-union-pacific-will-renumber-sd70-4014| archive-date=October 18, 2018}}{{Cite web|title=Diesel No. 4014 gets new number ahead of Big Boy debut|url=https://trn.trains.com/news/news-wire/2019/05/16-diesel-no-4014-gets-new-number-ahead-of-big-boy-debut|work=Trains|publisher=Kalmbach Media| date=May 16, 2019| access-date=May 28, 2019| archive-url=https://web.archive.org/web/20190528225142/https://trn.trains.com/news/news-wire/2019/05/16-diesel-no-4014-gets-new-number-ahead-of-big-boy-debut| archive-date=May 28, 2019}}}}

File:4014 drivers on lathe.jpg|alt=A steam locomotive driving wheel on the lathe|One of No. 4014's driving wheels on the lathe at the Strasburg Rail Road workshop in 2017

File:Union Pacific X4014 (49097041782).jpg|alt=A close-up of one of the articulated steam locomotive's set of wheels|A close-up of No. 4014's running gear in 2019

File:Union Pacific Big Boy 4014 Departs Granger, WY May 6th, 2019.jpg|alt=Two steam locomotives double heading and surrounded by railfans in the foreground|No. 4014 and No. 844 depart Granger, Wyoming, bound for Evanston, Wyoming, and Ogden, Utah, on May 6, 2019

File:Union Pacific 4014 Echo Utah (47807163711).jpg|alt=Two steam locomotives double heading and climbing a mountain range in Utah|No. 4014 hauling an excursion in Echo Canyon, Utah, in May 2019

File:The Great Race Across the Southwest November 2019 19.jpg|alt=An articulated steam locomotive pulling a passenger train|No. 4014 runs between Longview and Hallsville, Texas, in November 2019

File:Bigboy 4014 making a whistle stop at Kimball, Nebraska.jpg|No. 4014 makes a whistle stop in Kimball, Nebraska

File:4014 Accelerates East From Gering NE.jpg|alt=An articulated steam locomotive pulling a passenger train|No. 4014 accelerates east from Gering, Nebraska, in June 2023

File:UP 4014 Big Boy in Brigham City.jpg|No. 4014 in Brigham City, Utah bound for Soda Springs, Idaho and Cheyenne, Wyoming

File:Big Boy 4014 from Roseville for Winnemucca 2024-07-14 at Midas RR Crossing Rocklin 1R4A2255.jpg|No. 4014 leaving Roseville, CA bound for Sparks, Nevada, on July 14, 2024

File:Union Pacific Big Boy 4014 in Elverta, CA.jpg|No. 4014 runs south through Elverta, CA on UP's Sacramento Sub bound for Roseville, CA, on July 11, 2024