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Accident Report Detail

 
Hazardous Materials Accident at the Southern Pacific Transportation Company's Englewood Yard

Executive Summary

About noon on September 21, 1974, 2 loaded "jumbo" tank cars, cars 17 and 18 of a 145-car complement, were uncoupled as a unit at the crest of the gravity hump in the Southern Pacific Transportation Company's (SP) Englewood Yard at Houston, Texas. The two cars passed through the hump master retarder and group retarder without being slowed and accelerated as they moved down the grade into bowl track 1. At a speed of 18 to 20 mph, the two tank cars impacted an empty tank car. Upon impact, the coupler of the empty tank car rode over the coupler of car 17 and punctured the tank head. Butadiene spilled from the car and formed a vapor cloud, which dispersed over the area. After 2 to 3 minutes, the varpor exploded violently; as a result, 1 person died and 235 were injured. Total damages amounted to about $13 million, which included the destruction of 231 railroad cars substantial damage to 282 others.


Probable Cause

The National Transportation Safety Board determines that the probable cause of the overspeed impact was the failure of the retarding system to slow the two coupled tank cars and the absence of a backup system to control cars which pass through the retarders at excessive speeds. The failure of the retarding system was caused by foreign substances on the wheels of the two cars that preceded the two tank cars through the retarders.

Contributing to the accident was the failure of the Southern Pacific Transportation Company to enforce procedures to exclude cars with a foreign substance on their wheels from the humping system, and the Shell Oil Company's failure, after notification of the hazard, to eliminate spilled epoxy resin from the flangeways of their track.


Accident Location: Houston , TX    
Accident Date: 9/21/1974
Accident ID: 80327

Date Adopted: 5/21/1975
NTSB Number: RAR-75-07
NTIS Number: PB-243598/AS

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