By Railfan & Railroad Staff

On Wednesday, a Union Pacific “Big Boy” ran by itself on the main line for the first time since the steam era thanks to the installation of a new Positive Train Control system.

Earlier this week, the railroad announced UP 4-8-8-4 4014 would make a brief test run out of Cheyenne, Wyo., but an exact reason for the test was not given. But on Wednesday, photos and videos of the move posted online made it clear that UP was testing a new PTC system on the locomotive. Previously, UP used something called “LeaPTC,” which required it to run on the main line with a diesel locomotive. But now 4014 has PTC installed directly on it meaning it no longer will need to operate with a diesel (although it’s unclear if UP will let the locomotive venture too far without a diesel just in case mechanical issues crop up). The system is similar to one installed on Canadian Pacific 4-6-4 2816 last year. Like 2816, the PTC equipment has been installed in a cabinet in the tender. 

In 2021, it became the first main line steam locomotive to receive the technology.

UP 4014 will depart Cheyenne on June 30, as part of a month-long tour of Wyoming, Utah, Nevada, California and Idaho. The locomotive is expected to run again in the fall, venturing to Texas, Arkansas, Kansas, and Illinois, among other states.