Aerial photograph of the collision at milepost 527.1.

​Aerial photograph of the collision at milepost 527.1. (Photo courtesy of UP.)​​​

Collision of Union Pacific Railroad Train MGRCY04 with a Stationary Train

What Happened

​​On October 4, 2018, at 7:40 p.m. local time, eastbound Union Pacific Railroad freight train MGRCY04 (striking train) collided with the rear of stationary Union Pacific Railroad freight train MPCNP03 (stationary train) after cresting a hill and descending a grade for about 13 miles. The striking train consisted of 3 leading locomotives and 105 railcars. The locomotive engineer and conductor of the striking train were killed, and 3 locomotives and railcars 1 through 57 of the striking train derailed while the rear 5 railcars and the railcars positioned 8, 9, and 10 from the rear of the stationary train derailed. Damage was estimated by Union Pacific Railroad to be $3.2 million.

As the train descended the grade, the locomotive engineer initiated a full-service brake application, however, the train’s speed continued to increase. At milepost 529.95 the train was still accelerating, reaching 28 mph when the locomotive engineer initiated an emergency brake application. The event recorder indicated that information was being transmitted between the controlling locomotive and the rear railcar via a telemetry link for the previous 45 minutes. After the emergency brake application, the status of the communications system changed to “FR NC,” which means front-to-rear no communication. The emergency brake request was not received at the end-of-train device, which would have initiated an emergency brake application at the rear of the train. Five minutes after the locomotive engineer initiated the emergency brake application, the end-of-train device still had not received the emergency brake request, and the train collided with the standing train at about 55 mph at milepost 527.1. Prior to the collision, the crew of the striking Union Pacific Railroad freight train reported problems with the train’s air brake system and radioed the Union Pacific Railroad Harriman Dispatch Center to advise that they had accelerated to 51 mph and were unable to stop. The Union Pacific Railroad Harriman Dispatch Center notified the crew of Union Pacific freight train MPCNP03 and advised them to evacuate the train to avoid possible injury from the runaway train.

What We Found

We determined that the probable cause of the collision was the failure of the Union Pacific train MGRCY04 air brake system due to an air flow restriction in the brake pipe and the failure of the end-of-train device to respond to an emergency brake command. Contributing to the accident was the failure of Union Pacific Railroad to maintain the railcars in accordance with federal regulations, including regularly performing single railcar air brake tests. Further contributing to the accident were communication protocols, set by Federal Railroad Administration regulations and industry standards, that allowed extended time intervals for loss of communication notification between the head-of-train device and the end-of-train device without warning the train crew of the loss of communication.​

What We Recommended

​We made new recommendations to the Federal Railroad Administration and the Association of American Railroads, the American Short Line and Regional Railroad Association and the Association of American Railroads.