For the most up to date coverage of the I-95 collapse, click here.

An elevated section of I-95 in Northeast Philadelphia collapsed early Sunday after a tanker truck carrying gasoline burst into flames beneath it, severing the main expressway on the East Coast and causing travel chaos in the region that will be felt for some time.

Four northbound lanes fell onto Cottman Avenue in the city’s Tacony neighborhood after steel girders supporting the roadway were weakened in the searing fire, officials said. The interstate was closed in both directions between Woodhaven Road and Aramingo Avenue.

Standing within view of the collapsed and charred section of roadway Sunday night, Gov. Josh Shapiro said he would issue a disaster declaration Monday morning, a step that will allow Pennsylvania to receive federal aid.

“Remarkable devastation,” Shapiro said, describing his view of the scene from a helicopter. “I found myself thanking the Lord that no motorists who were on I-95 were injured or died.”

Read more of our coverage:

— Thomas Fitzgerald, Kristen A. Graham, Tom Avril, and Aubrey Whelan

Philadelphia schools will operate as usual on Monday.

“This minimizes disruption to school activities in our final days of the school year, aligns with anticipated plans of others in the area, and supports parents and guardians who must report to work,” spokesperson Monique Braxton said in a statement. “The district is prepared to operate student bus routes on their normal schedule. Students and staff will be expected to report to their school buildings at their regular start time.”

Still, if delays happen because of I-95-related road closures, “arrivals by any students and staff reporting late due to the road closure will be excused,” Braxton said.

A number of graduation and promotion ceremonies are planned for Monday; those events will proceed as planned, Braxton said.

Students’ final day of school is Tuesday; staff finishes the 2022-23 school year Wednesday.

— Kristen A. Graham

Both the city and state have said those looking for updates on the I-95 fire and highway collapse can check two separate websites.

Both sites include information about the latest detour routes; officials said they will be updated as new information develops.

– Kristen A. Graham

Michael McFadden doesn’t even want to think about the traffic implications of the I-95 collapse, he said.

“Oh Christ, it’s going to be a mess,” said McFadden. “This traffic’s going to kill the summer.”

McFadden and his wife Lisa live in Tacony, a few blocks from the site of the collapse. They walked as close as they could get to the wreckage, at Cottman and State Streets, and stood watching a phalanx of emergency personnel and vehicles.

Lisa McFadden works answering calls for the United States Postal Service; she was thinking about all the trucks that normally ferry mail from a Lindbergh Boulevard facility to post offices throughout the city - using I-95 to get around.

“There will be so many calls tomorrow, ‘Where’s my mail?’” said Lisa McFadden.

Side streets in the neighborhood are sure to be flooded with confused motorists, the McFaddens said. They already saw a spike on Sunday, before weekday traffic hits. And alternate roads will see an impact, too.

“You have a lot of accidents on [Roosevelt] Boulevard already,” Lisa McFadden said. “It’s going to be crazier now.”

– Kristen A. Graham

Officials are still investigating whether Sunday morning’s collapse resulted in any injuries or fatalities.

“At least one vehicle is still trapped underneath the collapsed roadway,” Gov. Josh Shapiro said. “We’re still working to identify any individual or individuals who may have been caught in the fire.”

Philadelphia authorities were not aware Sunday evening of any injuries or fatalities to motorists on I-95.

“We understand the situation remains fluid,” Mayor Jim Kenney said.

— Nick Vadala

Approaching the 12-hour mark after the fire that caused the collapse of a section of I-95 in Northeast Philadelphia, the scene was still bustling at Cottman Avenue and State Road.

Emergency vehicles and personnel crowded the area, and the rumble of heavy equipment working on the highway periodically pierced the air.

— Kristen A. Graham

In the wake of the bridge collapse in Northeast Philadelphia, SEPTA is “evaluating all options to enhance service for those who are impacted,” CEO and general manager Leslie Richards said.

SEPTA is working to finalize details for an immediate service plan for the early part of the week, and expects to finalize it Monday morning, Richards said.

The agency will add capacity on its Regional Rail service, including the Trenton, West Trenton, and Fox Chase lines. Those lines will have additional cars on already scheduled trains.

SEPTA’s Cynwyd Regional Rail line will be bused so that the agency can “repurpose equipment and personnel” for the Trenton line, Richards said.

Additionally, there will be free parking at all SEPTA-owned Regional Rail lots, as well as at the Frankford Transportation Center, Fern Rock, Fox Chase, and Torresdale lots.

Richards asked commuters and employers to work with SEPTA as they respond to an expected increase in demand for public transportation services.

“It is going to take longer than normal to get to work tomorrow,” Richards said.

— Nick Vadala

Pennsylvania Gov. Josh Shapiro said he would issue a disaster declaration in response to the collapse of a section of Interstate 95 in Northeast Philadelphia, allowing the state to access federal funding for repairs.

But a full rebuild of the collapsed section of the highway is still expected to take months.

“With regards to the complete rebuild of the I-95 roadway, we expect that to take some number of months,” Shapiro said Sunday. The exact timeline, he added, would be determined after the completion of a Department of Transportation investigation.

Shapiro said he would issue the disaster declaration on Monday morning. Doing so will allow the state to more quickly access federal funds to reconstruct the roadway. Secretary of Transportation Pete Buttigieg “made it clear” necessary resources will be provided, and delays in obtaining funding were not expected, Shapiro added.

“All of our federal partners have pledged complete and total support and assistance as we create alternative routes and as we rebuild I-95,” Shapiro said.

— Nick Vadala

Most bridges in the United States are not required to be fire-resistant, but the threat of fire is more common than many people realize.

Fire caused 30 U.S. bridge failures from 1980 to 2012 — roughly one per year — compared to just 20 failures from earthquakes, according to an analysis by University of Buffalo engineers.

Of the 30 bridges that failed due to fire, 13 were made of steel, like the one that collapsed Sunday morning on Interstate 95. Concrete bridges tend to be more fire-resistant, but they, too, can fail due to fire, accounting for five of those 30 failures. (The rest were wood.)

The steady occurrence of bridge fires has led some transportation agencies to study whether design codes should be revised accordingly, said Spencer Quiel, an associate professor of structural engineering at Lehigh University.

“These are low-probability but high-consequence events,” he said.

Quiel has tested the fire-resistance of various bridge construction materials at Lehigh. To protect steel girders from high heat, one option is covering them with a specialty coating called intumescent paint, he said.

“It creates a char layer that expands, which creates a thermal resistance layer,” he said.

Such paints already are used to protect steel beams in settings where fires are a greater risk, such as chemical plants and oil-drilling platforms.

– Tom Avril

Backhoes and other construction trucks sat near the the remains of the Cottman Avenue bridge on I-95 Sunday afternoon, the highway on either side emptied out.

The northbound lane of the highway had collapsed onto Cottman Avenue in a “V” shape, and the overpass was charred from the intense tanker fire that had raged beneath it.

Police, firefighters and other first responders had set up a staging area near the fire site, which is close to a number of industrial buildings and the Delaware River. Though the highway had been shut down for a long stretch of Northeast Philadelphia, traffic seemed light near the exits that were open.

— Aubrey Whelan

SEPTA said buses along Routes 70, 78 and 84 will be detoured until further notice due to the I-95 bridge collapse.For more information on those detours, go to septa.org/realtime/status

— Diane Mastrull

In a statement, the city health department said its Air Management Services division is monitoring air quality throughout the city. The city didn’t send inspectors to the site of the fire because it was extinguished quickly, spokesperson Jim Garrow said.

“There are not expected to be any air quality threats to the public due to the location and winds,” he said.

In a statement on Twitter, the Philadelphia Water Department said the spill had not impacted the city’s drinking water.

— Aubrey Whelan

The tanker that caught fire on I-95 Sunday morning had a capacity of 8,500 gallons and was carrying gasoline, according to the U.S. Coast Guard.

It was not immediately clear how full the tanker was before it caught fire and spilled its contents, but most of the gasoline has remained on land, a Coast Guard spokesperson said.

A slight sheen was visible on the nearby Delaware River, and agency personnel have deployed floating booms to limit the spread of gasoline.

Multiple agencies are involved in the cleanup on land.

— Tom Avril

Philadelphia residents in some areas will experience trash and recycling collection delays due to the collapse of a bridge on I-95, the city said in a statement Sunday afternoon.

The city said the Streets Department is still assessing which areas will be impacted as it diverts sanitation trucks to alternate routes. No specifics were offered on which streets or neighborhoods would be affected, or how long the delays might last.

— Rob Tornoe

PennDot has a recommended detour for getting around the I-95 collapse, and the information is being put on message boards in the region and in states north and south of Philadelphia, spokesman Brad Rudolph said.

Heading northbound:

Heading southbound:

» READ MORE: What commuters can do after the I-95 shutdown

— Thomas Fitzgerald

The girders that supported the collapsed I-95 bridge appear to be made of steel, a Drexel University engineer said after looking at Inquirer photos from the scene.

That means they were more susceptible to heat than if they had been made from steel-reinforced concrete, said Amir Farnam, an associate professor of Civil, Architectural and Environmental Engineering.

“There is no concrete surrounding them,” he said. “That means they are very susceptible to any sort of high temperature.”

Steel melts at temperatures above 2,500 degrees Fahrenheit, depending on the alloy used, but the metal starts to fail at temperatures well below that, Farnam said.

The metal loses about 20% of its strength at 750 degrees, and about half of its strength at 1,000 degrees, he said. Those temperatures are easily achieved with a tanker fire like the one that occurred Sunday morning, he said.

“When you have a fire like this and it lasts for a few hours, the yield strength of the steel decreases drastically, and it fails,” he said.

That doesn’t mean the bridge had a design flaw, he said. Given the tight space constraints, steel girders likely were the appropriate design choice, he said.

“You don’t expect an outdoor structure to experience fire,” he said.

Concrete is, however, used to surround the steel supports in buildings, in part because it’s an effective means of fireproofing.

Unless it fails. That’s what happened on 9/11, Farnam said. When planes hit the World Trade Center, the impact sheared off some of the protective concrete, exposing the steel underneath to high heat until it collapsed.

— Tom Avril

Fire Department Lt. Derek Bowmer said that earlier in the day, manhole covers had been exploding due to gasoline runoff. He said he couldn’t confirm that the truck under I-95 was a tanker.

Some runoff had gone into the Delaware River, but the Coast Guard has engaged in mitigation efforts there, Bowmer said.

He said he could not confirm whether anyone was injured in the fire but said that no city personnel responding to the scene had been hurt.

Police Inspector Francis Bachmeyer said in addition to the shutdown on I-95, police have closed off Cottman Avenue from Torresdale Avenue to State Road, and State Road from Rhawn Avenue to Princeton Avenue.

— Aubrey Whelan

Neighbors from the blocks around the fire gathered at the police line on Cottman Avenue to get a glimpse of the fire. Dawn Heller, who lives nearby, walked down after getting an alert on her Citizen app. “I couldn’t understand what happened — I had to come see for myself,” she said.

Sierra Jones woke up to a barrage of text messages from friends asking if she was okay — and then heard several muffled explosions.

She decided to walk down to Cottman Avenue to see the scene in person. “It’s mind-blowing,” she said.

Jones uses I-95 to get to her job as a massage therapist in Yardley and is unsure how she’ll do that now — she expects that traffic will clog her neighborhood like never before as people take alternate routes while the highway is closed.

“I guess I’ll just take the train,” she said.

— Aubrey Whelan

Both Pennsylvania Gov. Josh Shapiro and Philadelphia Mayor Jim Kenney are urging all residents to avoid I-95 in Northeast Philadelphia as officials respond to a bridge collapse that has shut down the highway in both directions.

“For now, please avoid the area and follow the direction of the first responders on the scene,” Shapiro said in a statement Sunday morning.

Neither offered any new information in statements, but Shapiro said his administration has been briefed and is coordinating with partners in Philadelphia, New Jersey, and the federal government in response to the collapse. Shapiro also said the Pennsylvania State Police and PEMA are on the scene assisting first responders.

— Rob Tornoe

In a short briefing Sunday morning, officials urged drivers to avoid I-95 in Northeast Philadelphia, which remains closed in both directions after a truck fire caused a northbound bridge to collapse between Cottman Avenue and Academy Road.

“I-95 will be impacted for a long time, for a long time,” said Philadelphia managing director Tumar Alexander.

About seven miles of I-95 are closed, from Allegheny and Castor Avenues (Exit 25) to Academy Road and Linden Avenue (Exit 32). Officials warn that other streets closer to the bridge are also closed due to the police and fire response.

“Today is going to be a long day,” said Dominick Mireles, the director of the city’s Office of Emergency Management. Mireles suggested it could be weeks before the roadway could be repaired.

“It’s heavy construction equipment that’s going to be required to come in to search and remove that debris,” Mireles said.

Officials said they believe a vehicle underneath the collapsed bridge continues to burn, and they’ll need to move in heavy equipment to deal with the remaining fire.

— Rob Tornoe

I-95 remains closed in both directions after a truck fire caused a bridge to collapse on I-95 in Northeast Philadelphia.

Police haven’t released many details about the incident.

Here’s what we know

Here’s what we don’t know:

— Rob Tornoe

A truck fire and partial road collapse have closed Interstate 95 in both directions in Northeast Philadelphia.

I-95 is closed between Cottman and Academy Roads, according to state transportation alerts.

The truck fire is under control, but the heat of it caused the collapse of the northbound lane of I-95 at Cottman Avenue and State Road, authorities say.

— Diane Mastrull