Union Pacific Railroad officials plan to conduct a full investigation into what caused four rail cars transporting hazardous chemicals to topple off the tracks near Peter Messina Road on Tuesday afternoon, company officials said.

The derailment prompted an overnight evacuation of houses in the surrounding neighborhoods that were located within 1,000 feet of the derailment.

Jeff DeGraff, director of media relations for Union Pacific, said it likely will take some time before the company gets definite answers on what went wrong.

“We’re going to be looking for defects in the tracks; pulling data from the train itself looking to see if there was a handling error, some operator problem,” DeGraff said Wednesday morning. “It’s going to take a little while.”

Parish officials said the rail cars were moving slowly when they tipped over.

Union Pacific crews were at the site Wednesday morning repairing the section of tracks where the four train cars tipped over around 1:30 p.m. Tuesday just north of the intersection at Peter Messina Road.

No injuries were reported in the crash, and authorities said there were no spills or leakage that would pose a threat to public safety.

The four train cars were transporting sodium hydroxide, propylene oxide, propylene dichloride and nitrogen blanket purge, authorites said.

But as a precaution, West Baton Rouge Parish President Riley “Peewee” Berthelot declared a local disaster emergency late Tuesday afternoon and issued the mandatory evacuation order for those living within 1,000 feet of the derailment as crews worked to right the tanker cars and clean up the crash site.

Lynn Cline, a spokeswoman for West Baton Rouge Parish, said 175 to 200 houses were affected, but only those living within 1,000 feet were evacuated. Other residents living in the Acadian Crossing and Sunset subdivisions were allowed to shelter in place, she said.

Cline said Wednesday that approximately 35 households living in close proximity of the derailment site evacuated overnight.

The parish lifted the evacuation and “shelter in place” order at 1:15 a.m. Wednesday morning and all the residents were allowed to return to their homes after the rail cars were uprighted and moved into a storage facility at the yard.

DeGraff said Union Pacific crews were working on track repairs all day Wednesday.

“We pulled the rail track out and replaced them,” he said. “Nothing we’re doing is impairing traffic or our main rail line.”

DeGraff said the company will continue to monitor the four rail cars that derailed to ensure there is no leakage in the days that follow.

Sodium hydroxide is an inorganic compound used mostly as a chemical base in the manufacture of household cleaners as well as pulp and paper.

Propylene oxide is an organic compound used in the production of polyurethane plastics.

Propylene dichloride is an odorless and flammable organic compound used in the production of perchloroethylene and other chlorinated chemicals.

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