A broken rail led to this Union Pacific derailment on a Tempe, Ariz., bridge in July 2020, the Countrywide Transportation Basic safety Board has established. (Sol Tucker)

TEMPE, Ariz. — A damaged rail is the possible cause of a derailment of a Union Pacific educate on a Tempe bridge in July 2020, which led to a hearth, collapse of element of the bridge, and a release of harmful content, according to a report unveiled Thursday by the National Transportation Basic safety Board.

The severity of the incident reflected the lack of an internal guard rail on the wood bridge, which permitted the devices to go laterally into the steel bridge, producing the partial collapse, in accordance to the report.

The broken rail was on a wooden trestle solution to the steel bridge around Temple City Lake, and led to the derailment of 12 autos of the three-locomotive, 97-car train soon just after 6 a.m. on July 29, 2020. The educate was moving at 23 mph at the time of the derailment. jOne of the derailed vehicles strike the bridge composition, leading a collapse of aspect of the bridge and sending railcars and the bridge on to Rio Salado Parkway below [see “No estimate for repair of UP bridge …,” Trains News Wire, July 30, 2020].

Among the autos which fell from the bridge have been two DOT-111 tank autos carrying cyclohexanone, a flammable harmful product applied in the making of nylon just one of these cars and trucks leaked about 2,200 gallons of the liquid, but it did not ignite. The fire on the bridge concerned flatcars of lumber. A single firefighter was addressed for smoke inhalation at the scene there have been no other accidents.

Union Pacific approximated in general problems from the accident to be pretty much $11 million: $10 million for the bridge, $485,000 to railroad devices, and $435,000 to monitor and structures. The bridge was closed for about two months as a consequence [see “Union Pacific expects to reopen burned Arizona bridge …,” News Wire, Aug. 6, 2020].

The NTSB investigation located that the monitor on the bridge experienced been inspected just two times prior to the incident, and discovered no keep track of flaws examination of the guide locomotive’s front-experiencing camera confirmed no evident anomalies. The investigation also identified that an inner guard rail that experienced existed on the approach to the steel bridge had been eliminated for former bridge perform and had not been changed UP rebuilt the bridge with internal guard rails extending 50 ft to the north and south of the steel construction.

Photo of derailment with notations
An illustration from the NTSB report reveals details of the Tempe derailment. (Union Pacific image with NTSB notations)