What Really Happened to Union Pacific's Tier 4 SD70s

A story told online says Union Pacific's Tier 4 SD70s were all scrapped within a few years. Yet at least eleven of them were photographed this year, from Donner Pass to Memphis, and The Diesel Shop's roster lists 87. We follow Union Pacific's own filings and earnings calls, the EPA's rule and the railroad press to find what really happened: a locomotive that came late, built around a new engine, just as Union Pacific began parking thousands of locomotives. Yes, the narrator is AI. I'm a train fanatic with a voice that would clear a room, so I let a robot read it. Everything else is done by hand: every fact comes from Union Pacific's own filings and earnings calls, the EPA's rule, the builders' releases, railfan rosters and the railroad press, and I check every line before it goes up. No invented quotes, no made-up documents, no AI slop. Get something wrong and I'll fix it: tell me in the comments with a source. More from Locomotive Geek: The Nebraska Town That Fed About Six Million Troops at Its Train Station    • The Nebraska Town That Fed About Six Milli...   Why Did Union Pacific Scrap Its First Streamliner So Soon?    • Why Did Union Pacific Scrap Its First Stre...   Locomotive Geek: The railroads, one story at a time. CHAPTERS 00:00 The story online 01:30 The Paper Trail 04:06 The Deadline 07:49 A New Engine 10:16 Union Pacific's Eighty-Seven 12:55 Three Thousand Parked 18:15 Rebuild, Don't Buy 21:24 The Missing Numbers 22:58 Back in Production 25:23 What Really Happened SOURCES Union Pacific: Form 10-Ks for 2018 to 2023 and SEC filing data, Form 8-K releases (Sept 2018, Jan 2019), earnings calls 2019 to 2022 (Motley Fool and MarketBeat transcripts), Inside Track (21 Nov 2016), UP news (27 Jul 2022) The rule: EPA final locomotive rule, Federal Register (30 Jun 2008), 40 CFR 1033, EPA release (14 Mar 2008). FRA accident data (Form 54) Builders and buyers: Progress Rail releases (4 Oct 2015, Jan and 8 Apr 2026), product page and SD70ACe-T4 brochure; Wabtec (4 Feb 2026); CPKC (21 Jan 2026) Press: Progressive Railroading (2008 to 2026), Railway Gazette (2015, 2026), Railfan & Railroad (2021, 2022, 2025), FreightWaves (Jim Blaze, 2020; Stuart Chirls, 2026), KSL.com (John Hollenhorst, 26 Apr 2020), Railway Age (25 Apr 1942), CSX Transportation Historical Society (2020), Akron Railroad Club (2016, 2019) Rosters and dated photos: The Diesel Shop (revised 6 Oct 2026), and 2026 photos on Flickr by Christopher Scurlock, James Belmont, R Kilpatrick and others IMAGE CREDITS Tyler Silvest from Olathe, Kansas, CC BY 2.0: https://commons.wikimedia.org/?curid=... https://commons.wikimedia.org/?curid=... https://commons.wikimedia.org/?curid=... https://commons.wikimedia.org/?curid=... https://commons.wikimedia.org/?curid=... https://commons.wikimedia.org/?curid=... https://commons.wikimedia.org/?curid=... https://commons.wikimedia.org/?curid=... https://commons.wikimedia.org/?curid=... https://commons.wikimedia.org/?curid=... https://commons.wikimedia.org/?curid=... https://commons.wikimedia.org/?curid=... https://commons.wikimedia.org/?curid=... https://commons.wikimedia.org/?curid=... https://commons.wikimedia.org/?curid=... https://commons.wikimedia.org/?curid=... https://commons.wikimedia.org/?curid=... https://commons.wikimedia.org/?curid=... https://commons.wikimedia.org/?curid=... https://commons.wikimedia.org/?curid=... Jim Hamilton, CC BY 2.0: https://commons.wikimedia.org/?curid=... https://commons.wikimedia.org/?curid=.... kitmasterbloke, CC BY 2.0: https://commons.wikimedia.org/?curid=... Shown whole, with labels beside them: Jerry Huddleston, CC BY-SA 2.0: https://commons.wikimedia.org/?curid=.... Taylor Woolston, CC BY-SA 4.0: https://commons.wikimedia.org/?curid=.... Wheresmything, CC BY-SA 4.0: https://commons.wikimedia.org/?curid=... Public domain: Carol M. Highsmith, Library of Congress (Bailey Yard, North Platte; Cisco, Texas; near Spencer, Idaho) Photos are cropped, panned or zoomed, and some have text added. The thumbnails are crops of Tyler Silvest's, Jim Hamilton's and Carol M. Highsmith's photos credited here, with text added.