The NTSB has released a preliminary document regarding the UP derailment and fire in Tempe, Ariz.
The docket for this investigation includes more than 1,300 pages of factual information, including reports on operations, mechanical, track and engineering, metallurgical testing, hazardous materials, risk assessment, bridge and structures, and emergency response efforts. The docket also includes interview transcripts, photographs, and other investigative materials.
The docket contains only factual information collected by NTSB investigators; it does not provide the final report, nor does it contain analysis, findings, recommendations, or probable cause determinations. As such, no conclusions about how or why the derailment happened should be drawn from the information within the docket. The NTSB will issue a final report at a later date that will include analysis, findings, recommendations, and probable cause determinations related to the derailment.
The derailment happened when a westbound Union Pacific Railroad freight train traveled over a wooden trestle leading up to a steel superstructure bridge over Tempe Town Lake. Twelve cars of the train derailed, and the train struck the bridge, which then collapsed. Three cars carrying hazardous material released about 2,200 gal of flammable material but did not catch fire; however, lumber spilled from the derailed equipment did ignite. No injuries were reported in connection with the accident.
The public docket for this investigation is available online at https://go.usa.gov/xFKgy.