Los Angeles residents will have to wait three to five weeks before they can access the Interstate 10 freeway.

The state will be making repairs to the freeway's bridge deck and columns after a massive fire charred and chipped 100 columns – with 9 or 10 severely damaged, said Gov. Gavin Newsom at a news conference on Tuesday.

The California Department of Transportation evaluated core samples from the upper deck of the freeway to evaluate the structural damage before making the determination, Newsom said. The blaze also twisted the freeway deck guardrails.

State officials were considering a rebuild of the freeway if it could not be repaired, Newsom said.

"This will not be a demo. We will not need to demolish and replace the I-10," Newsom said at the site of the damage. "We will continue the kind of repairs you're seeing being done behind me and continue a shoring plan to shore up this site."

The highway remained closed on Tuesday between Alameda Street and the East L.A. Interchange, according to the California Department of Transportation.

The fire was set intentionally and maliciously, State Fire Marshall Daniel Berlant said at a news conference Monday. The case is under investigation as an act of arson.

Gov. Gavin Newsom, State Fire Marshal:Arson is behind fire that damaged major section of Los Angeles freeway

Strong concrete in freeway structure

Caltrans told USA TODAY on Tuesday that concrete in structures gain strength slowly for a very long time and that older structures "frequently have concrete stronger" than what had been designed. Bora Gencturk, associate professor and director of the Structures and Materials Research Laboratory at the University of Southern California, said that even though the concrete has degraded a little due to the fire, "that strength may still be sufficient because it was originally stronger than what they intended to use."

According to Gencturk, concrete can resist fire up to 662 degrees (350 degrees Celsius), The concrete cover fell off the columns, indicating that temperatures were very high during the blaze, but localized to one area of the structure, he said.   

Officials have compared the emergency to the collapse of Interstate 95 in June. But Gencturk said I-95 used steel bridge beams to support the deck, whereas the freeway in Los Angeles used concrete.

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Angelenos urged to 'work together'

On Monday, Los Angeles Mayor Karen Bass urged commuters to downtown Los Angeles to take public transportation or work from home due to the major transportation disruptions.

"Angelenos, it's good news!" Bass said at the news conference on Tuesday. "But it's still 3 to 5 weeks in Los Angeles for this freeway not to be in operation ... We need Angelenos to work together; to not turn against each other." She said she's heard several stories about road rage since the onset of the disruption.

Los Angeles commuters should use the E, J or A Line Metro trains to access downtown Los Angeles, Los Angeles County MTA CEO Stephanie Wiggins said.

Drivers who need to use the interstate should stay on the freeway and avoid local streets and people going downtown should use "surface streets," Los Angeles Department of Transportation General Manager Laura Rubio-Cornejo said.

"It is critical that drivers heed the signs and traffic officer instructions in order to maintain the safe movement of people through the impacted area," she said.

'24-hour operation, 7 days a week - rain or shine'

The state is working to mitigate the impact and work quickly, Newsom said. Debris removal will be complete in the next few days, he said. And the reparation process is a "a 24-hour operation, 7 days a week - rain or shine," he said.

"We're going to do everything in our power to move that in to the more immediate future and not extend this to that five-week period," he said.

While state officials have estimated that the freeway may be closed for weeks for repairs, Gencturk said the timing of things will be very accelerated compared to what we typically see given the urgency of the situation.

"We adapt to the conditions," he added. "Three to five weeks is obviously not perfect, but I think it's going to be manageable."

Contact Kayla Jimenez at [email protected]. Follow her on X, formerly Twitter, at @kaylajjimenez.