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Accident Report Detail

Head-on Collision, Union Pacific Railroad

Executive Summary

About 2:00 a.m., on January 31, 1996, a Union Pacific Railroad unit coal train CNAIM004-30 separated between the fourth and fifth locomotive units while the train was ascending a 1-percent grade. The train's automatic air brake system did not hold the train in place and the fifth locomotive unit and all 114 cars began an uncontrolled downhill movement. A helper locomotive en route to assist the unit train was warned of the runaway train by radio, and the crew abandoned their train.

Probable Cause

The National Transportation Safety Board determines that the probable cause of this accident was the failure of the brake cylinder hose fittings to maintain air in the brake cylinder during extreme cold weather and the failure of the crew to apply the hand brakes to the separated train. Contributing to the cause of the accident was Union Pacific management dispatching trains in this territory with tonnage near the tensile strength of the couplers.

Accident Location: Nacco , WY    
Accident Date: 1/31/1996
Accident ID: LAX96FR006

Date Adopted: 8/18/1998
NTSB Number: RAB-98-06
NTIS Number:  

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