FEDERAL RAILROAD ADMINISTRATION
1200 New Jersey Avenue SE, Washington, D.C. 20590

PRELIMINARY FACTUAL FINDINGS REPORT
Derailment of Union Pacific’s Unit Crude Oil Train ONETU 02
Transporting Bakken Crude Oil for U.S. Oil
Mosier, Oregon

June 23, 2016

 Contents
EXECUTIVE SUMMARY .......................................................................................................................... 1
Union Pacific/U.S. Oil Mosier, Oregon Crude Derailment ...................................................................... 1
FRA’s Factual Findings ............................................................................................................................ 2
Cause ..................................................................................................................................................... 2
Tank Cars .............................................................................................................................................. 2
Braking.................................................................................................................................................. 2
Conclusion ............................................................................................................................................ 2
FRA Actions Since Derailment................................................................................................................. 3

 EXECUTIVE SUMMARY
Union Pacific/U.S. Oil Mosier, Oregon Crude Derailment
At 12:15 p.m. Pacific Daylight Time on Friday, June 3, 2016, a Union Pacific train, ONETU 02,
transporting Bakken crude oil for U.S. Oil & Refining Company and operating on Union
Pacific’s Portland Subdivision derailed near the town of Mosier, Oregon (at milepost 69.02). A
total of 16 tank cars derailed.
Train ONETU 02 was traveling at a speed of approximately 25 mph at the point of derailment.
The speed restriction for this section of track is 30 mph due to the curvature of the track.
The train originated in New Town, North Dakota, and was destined for Tacoma, Washington.
The train consisted of two head-end locomotives, one distributed power locomotive at the rear,
two buffer cars, and 94 tank cars loaded with Bakken crude oil. The train was operating with
conventional air brakes.
Dakota Plains loaded the tank cars for U.S. Oil in New Town, North Dakota. Dakota Plains
reports the crude oil had a vapor pressure of 9.2 psi, measured at the loading facility.
The tank cars in train ONETU 02 were general purpose specification DOT-111 tanks cars,
modified to the Association of American Railroads (AAR) CPC-1232 standard. The cars were
equipped with full-height head shields and metal jackets with insulation. The cars did not have
thermal protection. These cars are commonly referred to as “jacketed 1232s.”
During the derailment, a coupler struck one tank car, mechanically puncturing it. This puncture
allowed crude oil to come into contact with an ignition source, leading to a fire that burned for
approximately 14 hours. Four cars were eventually involved in the fire.
The four tank cars involved in the fire were the punctured car, and three additional tank cars –
two that had their bottom outlet valves sheared off in the derailment, and one car with the gasket
melted out from under the manway cover.

1

 FRA’s Factual Findings
Cause
FRA’s preliminary investigation determined the Union
Pacific derailment was caused by broken lag bolts leading to
wide track gauge.
FRA’s investigation found that multiple lag bolts in this
section of Union Pacific track were broken and sheared,
leading to tie plates loosening from ties. The loosened tie
plates allowed for the rails to be pushed outwards as trains
moved across them, eventually resulting in an area of wide
gauge, leading to the derailment.
Tank Cars
The tank cars involved in the derailment performed as
expected in the incident based on tank car performance
metrics.
Braking
The Union Pacific train was equipped with an air brake
system and was operating on distributive power.

Image 1:
Image of broken bolts that allowed rails
to go wide, causing wide gauge.

Following the derailment, FRA’s Office of Research and
Development conducted simulations modeling the derailment of Train ONETU 02, assuming the
consist was equipped with conventional breaks, distributive power or electronically controlled
pneumatic (ECP) brakes. (Distributive power provides power to the train from both ends of the
consist and provides improved braking over air brakes. ECP brakes use an electronic trainline
signal to activate brakes on all cars throughout a train consist simultaneously.)
As has been the case with previous instances of modeling, FRA’s simulation found that applying
the brakes uniformly and instantaneously would have provided additional train control,
potentially shortening the stopping distance, and leading to a less severe derailment.
In this specific model, the simulation found that if Train ONETU 02 had been equipped with
ECP brakes, two fewer tank cars may have derailed, and one less tank car may have been
punctured.
Conclusion
Unless or until additional details come to light, FRA has made the preliminary determination that
Union Pacific’s failure to maintain its track and track equipment resulted in the derailment.
Broken and sheared lag bolts, while difficult to detect by high-rail, are more detectable by
walking inspection combined with indications of movement in the rail or track structure and/or
uneven rail wear, and are critically important to resolve quickly.

2

 FRA Actions Since Derailment
Following the derailment, FRA took the following actions to inspect and ensure safety along this
route:
● FRA conducted walking inspections of all the curves in the Columbia River Gorge to
inspect for additional track, fastener, or bolt issues.
● FRA conducted similar inspections of BNSF track on the Washington side of the
Columbia River.
● FRA conducted a data search of FRA databases for tie fastener trends across the rail
industry.
● Volpe, one of the Department of Transportation’s research centers, is testing the
metallurgy of the broken bolts.
● Ran a geometry car with a Gage Restraint Measurement System on Union Pacific track to
rule out wide gauge on Union Pacific’s Portland, Ayer, and Spokane subdivisions.
● Confirmed that nine Union Pacific temporary speed restrictions remain in place along
Union Pacific’s Portland Subdivision, including a 10 mph speed restriction in Mosier.
● FRA is evaluating potential enforcement actions, including violations, and other actions
to ensure Union Pacific’s compliance with applicable safety regulations.

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