NTSB releases probable cause of Tempe Town Lake train derailment and bridge collapse

Tempe bridge collapse: NTSB releasing investigation report on incident

The bridge, which was built in 1912, collapsed following a derailment in 2020. FOX 10's Nicole Garcia has more on the report's findings.

TEMPE, Ariz. - Federal investigators have released a new report into the cause of a 2020 train derailment in Tempe.

The derailment, which involved 12 rail cars, caused a bridge over Tempe Town Lake to collapse. No one was hurt as a result of the incident.

According to the City of Tempe's website, the rail bridge, officially called the Salt River Union Pacific Bridge, was built in 1912. 1912 was the same year Arizona became a state.

The findings

According to the latest investigation report released by the National Transportation Safety Board in June 2022, a broken rail was the likely cause of the incident, citing that the wheels on two cars showed damage, an indication they had gone over a broken rail. In addition, a damaged rail was discovered.

"Contributing to the severity of the derailment was the absence of an inner guard rail preceding the steel bridge structure, which allowed the derailed equipment to move laterally into the bridge structure and cause its collapse," the report added.

There were 97 rail cars on the train, and 47 cars passed before the rail broke under the 48th car.

In all, Union Pacific, which operates the railroad and bridge, spent $11 million building and repairing the bridge, as well as its surroundings. We reached out to Union Pacific regarding the findings, and a representative of the company said they are still reviewing the report, and could not immediately comment.

Former Tempe resident talks about incident

Elizabeth Dietchman lived near Tempe Town Lake in 2020, and aw first hand the fiery aftermath of the derailment and bridge collapse.

"I was on the ground crying," said Dietchman. "It was so impactful for me. I really didn't feel safe at home anymore."

The incident prompted Dietchman to make a major life change.

"Living near a situation where I could've been hurt or killed, I wasn't comfortable with the way local authorities handled the situation, so I'm no longer living in Tempe," said Dietchman.

Rail bridge was the scene of prior derailment incident

Reports: Another derailment had happened at bridge that collapsed following derailment and fire on July 29

The derailment reportedly happened in June.

This was not the first train derailment on the bridge for summer 2020.

According to Phoenix Fire Department officials at the time, crews responded to a partial derailment on the same bridge on June 26 after some of the rail ties caught fire.

Union Pacific officials said the bridge was damaged, and was subsequently repaired. It reportedly took two days to repair and reopen the bridge. They also said the bridge had received its yearly inspection on July 9. They won’t release what the inspection found, instead saying it is in the hands of NTSB.

Elizabeth Dietchman, who lived in the area at the time, took photos of the scene a month prior to the incident, showing crews working on the bridge following the 1st derailment.

"I also recorded the security guard saying it's not a big news story," said Dietchman. "Then a month later, it was a big news story."

Incident sparked massive blaze

A bridge over Tempe Town Lake caught on fire and partially collapsed after a train derailed on the morning of July 29.

Tempe Fire Department officials say the derailment happened around 6:09 a.m., and involved a Union Pacific train. Fire crews with multiple fire agencies responded to the scene.

At one point, fire officials say the fire was designated as a four-alarm, which Tempe Fire officials say represents a big event in the world of firefighting.

Union Pacific spokesperson Tim McMahan says none of the train’s crew members were hurt, but there was a report of someone suffering from smoke inhalation. McMahan also says eight to 10 rail cars caught on fire.

Some cars carried flammable liquid

Train derailment results in fire, partial bridge collapse, and chemical leak

The fire happened at a bridge over Tempe Town Lake. FOX 10's Matt Galka reports.

Some of the train’s cars carried lumber and others were tanker cars, and three tank cars fell into the park below. Tempe Fire officials say some of the cars contained cyclohexanone with the third containing a rubber material.

Cyclohexanone is a flammable, colorless oily liquid, and nearly 95% of its manufacturing is used to make nylon, according to the National Library of Medicine.

Fire officials say smoke from the fire is toxic, and there is a cyclohexanone leak. The leaked content is not going into Tempe Town Lake, according to fire officials, and the cause of the derailment is under investigation.

The leak was contained and cleaned up on July 30.

The Associated Press contributed to this report.

Train derailment results in fire, partial bridge collapse and chemical leak

The train was on a bridge over Tempe Town Lake when the incident happened. FOX 10's Bailey Miller reports.

Frame by frame: Train derailment at Tempe Town Lake

The pictures from this derailment were very dramatic. FOX 10's Troy Hayden had a chance to watch the event unfold live on July 29 and he's breaking down the video for us.

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