On November 10, 2023, one of Los Angeles’ busiest freeways and part of the fourth longest interstate in the U.S., the I-10, also known as the Santa Monica/San Bernadino Highway, closed due to damage from a massive fire that engulfed two nearby storage yards and is alleged to have been arson.
Surprisingly, the initial estimate of at least six months to repair the damaged roadway became a mere eight days. Although additional repairs continue, the highway, that carries 300,000 cars daily, reopened on November 18, 2023.
On the other side of the nation, in Philadelphia, a section of Interstate 95 collapsed on June 11, 2023 after a gasoline tanker truck caught fire and damaged the steel girders reinforcing the roadway bridge, closing off a “crucial artery for both local traffic and regional commercial travel” according to Drexel University’s College of Engineering.
Much like the astonishing effort in Los Angeles, traffic on Pennsylvania’s I-95 was back up and running on a temporary raised six-lane road – that was erected in just 12 days to return the 160,000 cars and trucks that drive it daily to proceed – while permanent repairs were made to the damaged bridge structure.
So, we wanted to know – how did they do that?
Road Damages: A National Problem
These are just two high-profile freeway collapses of the many road and bridge damages that occur throughout the United States at any given time. Compiled figures put the number of fatalities caused by these damages at 42,000 lives annually.
The American Society of Civil Engineers (ASCE) currently grades the average state of the nation’s roadways and bridges at a C-, up from its previous D+ grade, mainly due to the targeted infusion of federal funds as part of the Bipartisan Infrastructure Law, in 2021.
ASCE rates some 43% of U.S. roadways as mediocre or poor and in need of immediate repair.
The Society estimates that the nation spends $24,000 per mile of road on operation & maintenance per year. There are 4.17 million statute miles of highway in the U.S. (1 statute mile = 5,280 ft., or one eighth of an inch longer than an international mile). So, various states’ Departments of Transportation, and local, state, and federal government’s expenditures on maintenance and repair, cost approximately one hundred billion, eighty million dollars ($100,080,000,000) annually.
Each state spends their per capita road monies differently. In 2020, for instance, Alaska spent $1,858 per person on their highways, the highest per capita, while Arizona spent the least with $425. The national average for per-person highway spending was $616 in 2020, which reflects a 24.7% increase in spending over 2010 levels.
The Bipartisan Infrastructure Law is expected to drastically change spending habits, however, as it included $110 billion for road and bridge infrastructure repair and improvements, much of which will be matched by state and private funds.
Interstates 10 and 95 each have their own unique characteristics and challenges. It’s important to understand that the two newsworthy projects this article focuses on are not an “apples to apples” comparison. They are, however, valuable case studies that demonstrate how public policy decisions, plus incredible feats of engineering, construction, and sheer willpower, made the impossible, possible.
So, what does it take to reopen a major highway?
9-1-1 For Funding
In the cases of both I-95 and I-10, Governor Shapiro in Pennsylvania and Governor Newsom in California declared States of Emergency almost immediately. This is important because it allowed the release of state and federal funds to speed repairs.
The Pennsylvania repairs received $3 million in Quick Release federal funds and another $7 million in state funds to get the road open again. The final price tag on the permanent repairs is estimated at “$25-30 million, with the federal government pledging to cover the majority,” according to 6abc in Philadelphia.
I-10’s fire damage also received $3 million in Quick Release funds from the federal government. There are no apparent figures available on the amount of state funds that have been committed thus far, but the final price tag on the permanent repairs is expected to be around $10 million.
All Hands On Deck!
For both the I-95 and I-10 closures, PennDot (in Pennsylvania) and Caltrans (in California) adopted a 24-hour schedule of rotating crews to complete initial repairs and reopen the roads as quickly as possible. They also employed some unexpected practices and materials to get the job done.
I-95: A Case Study in Construction Innovation
In Pennsylvania, the exact wording of Gov. Shapiro’s emergency declaration gave the state’s Transportation Secretary, Mike Carroll, a lot of weight to get things moving. Shapiro called for PennDot to “replace the bridge in the speediest session possible,” and U.S. Secretary of Transportation, Pete Buttigieg, pledged the full support of the federal government to assist.
The National Transportation Safety Board has taken charge of the investigation of the crash and collapse, which led to just one fatality – the driver of the tanker truck. The U.S. Coast Guard and the Water Department of the City of Philadelphia were quick to conduct environmental assessments to gauge the impact of the gas fire and spill on the surrounding area and community.
Demolition on the damaged highway began within three hours of the accident, thanks to a crew from C. Abbonizio Contractors, Inc. who were already working on another part of the road nearby, and local police officers later provided special escorts for expedited shipments of asphalt and building materials to the site for use by Buckley & Co., Inc., the general contractor chosen to head up the repairs.
Weather always plays a part in outdoor construction, and when you have 200 people working in 12-hour shifts, 24 hours a day, a storm can wreak havoc. When rains threatened to stall paving on the newly built bridge, the Pocono Raceway in Long Pond, Pennsylvania provided PennDot with a Track Jet Dryer, used to dry tracks for NASCAR races. This also allowed stripe painting to occur as soon as the asphalt was laid to save additional time. But the track dryer wasn’t the only innovation employed by Secretary Carroll and his team.
How Glass Saved the Day in Philly
Eight million bottles-worth of recycled foamed glass aggregate – measuring approximately 8,000 cubic yards – was placed to create an embankment for the new roadway before paving.
Ultra-light foamed glass aggregate is known as an MSE – mechanically stabilized earth – and is created by grinding the glass to a fine powder and mixing it with a silicon carbide, which acts as a foaming agent. That mixture is then kiln heated and softened. The foaming agent reacts to the heat and dissipates, creating bubbles within the glass, which makes the foamed glass aggregates.
The new material looks a lot like standard gravel, but it is much lighter than gravel or soil, requires far less compaction, and does not require waiting to achieve optimal moisture levels before adding the weight of a structure on top of it. So, it helps to protect underground infrastructure while reducing construction time. For I-95, that infrastructure included water and sewer lines that could have been damaged or crushed by heavier fill material.
This wasn’t the first time Aero Aggregates of North America, LLC had dealt with the problem of supporting a structure while avoiding crushing the utilities below. It is one of the primary applications of the material that is routinely used to help expand roadways and slab foundations above existing utilities. “[T]hey realized there was a sewer line and you can’t put weight on it… But this is the first job where we had to do something so fast,” the company’s CEO, Archie Filshill, told Engineering News Record (ENR).
In a recent phone interview for this article, Filshill provided a glimpse into how quickly events unfolded in the aftermath of the accident. The crash occurred at approximately 6:30AM. Filshill received his first call, from Buckley & Co., Inc. President Rob Buckley at 8:15AM, which was immediately followed by a call from PennDot, both less than two hours after the crash.
Once the aggregate was placed, it was surrounded with a high-tenacity geosynthetic reinforcement called a polyester geogrid, and compacted with just four passes of a steamroller, which allowed precast parapet and moment slabs to be laid, so that paving could happen immediately instead of waiting for 7-28 days for poured concrete to cure.
Filshill noted that to get a quick vertical build with the aggregate, the standard practice is to construct a temporary wire frame “basket” that is welded on the outside of the reinforced walls before adding concrete. This is the process used on I-95.
The foamed glass aggregate sped repair time by as much as 400%, Filshill told CNN last year. Plus, unlike soil or concrete, the ultra-light aggregate isn’t impacted by rain or other weather. It has been used in other construction projects throughout Pennsylvania and at least 22 other states, at sites including the Philadelphia Navy Yard and the Philadelphia International Airport.
“[The aggregate fill and precast slabs] sped up the process by weeks, because normally, you’d have to pour a moment slab and then pour a parapet on top of it,” Chad Lavallee, a Buckley & Co., Inc. engineer with previous PennDot repair experience told ENR in June of 2023.
The decision to utilize this novel approach was made easier by Joseph Sirignano, Vice President at Benesch, who had helped design the bridge on the exact segment on I-95 in question less than a decade prior. The existing bridge was a welded steel I-beam structure spanning 104 feet, that was completed in 2016. Sirignano told ENR that PennDot and the contractors, along with his team, made the call because Benesch had used a similar “temporary road with wire walls and the glass aggregate fill… on two other projects.”
The nearby availability of the Pennsylvania-manufactured material and PennDot’s previous approval of its use on other projects, along with the need for speed, were all considerations that the general contractor had to take into account, according to Filshill. “[The solution] had to be ultra lightweight, extremely fast, and not impacted by weather.”
“The first day, the skies opened up. There was a torrential downpour, and Buckley’s crew did not stop for a second,” said Filshill.
“The recurring theme – and I’ve been in this business for 30 years – was the amount of collaboration on this project. The best example of hands-on teamwork I’ve ever seen.”
Governor Shapiro praised the monumental effort by all involved, saying, “They worked through the rain, they worked through the night, they worked through the heat, and a bunch of dads worked on Father’s Day.”
I-10: Lessons from an Earthquake & Surprises Led to a Shrinking Schedule
“This will not be a demo,” California Governor Gavin Newsom said in a news conference on the morning of November 14, 2023, just four days after fire took down a key portion of Interstate 10. “We will not need to demolish and replace the I-10, so we will continue the kind of repairs you see being done and continue a shoring plan.”
Newsom’s remarks were a complete one-eighty from the six-month closure that the media and Los Angelenos had been told to expect when plans were made to demolish the 450 ft. section of elevated roadway, including some 100 columns, and build another segment that could support the 300,000 vehicles that travel the I-10 daily. The city’s commuters and commerce sector braced for months of delays and the financial impact that would follow.
“Economic prosperity was a concern,” said Ramon Hopkins, Caltrans Construction Division Chief, as he summarized in a virtual event in January of 2024, sponsored by BuildOUT California, AGC of California, and CALINFRA.
Luckily, core sample examinations of the columns and bridge deck and hazardous material testing allowed engineers and Caltrans to determine there was far less damage to the highway than expected, and they made the decision to strengthen the existing roadway and rebuild. Even with that stroke of luck, the expectation was that it would take three to eight weeks to get traffic moving again.
Additional structural analysis, however, determined that only seven rows of pillars supporting the roadway were impacted or showed signs of spalling, referring to concrete damage caused by exposure to extremely high temperatures. Eight columns will require complete replacement, as their fire damage is more extensive. Original estimates expected 14 concrete support column rows would need extensive repair or replacement. Halving the number of damaged columns also reduced the timeline.
“Let me just assure you that the reason why the freeway is going to be open quickly is because the deep structural damage that we were worried about did not take place,” Los Angeles Mayor Karen Bass assured the media and public in a November 17, 2023 news conference.
Northridge Quake Paved the Way for Quick Action
Instead of the purchasing and contract delays that normally accompany such a roadway project, Gov. Newsom instructed Caltrans to utilize the same contracts they used in the wake of the Northridge Earthquake in 1994, which allowed incentivized contracts to be awarded almost immediately to Security Paving and Griffith Company for debris clean-up and shoring of the structure.
“We are working the details of the contracts in real time,” the Governor said. “We are taking lessons learned from the Northridge quake as it relates to incentives for contracts.”
The Northridge Earthquake was a 6.7 magnitude quake that injured thousands of Southern California residents, killed 72 of them, and, according to the California Department of Conservation, cost more than $60 billion in damage and economic losses, “making it the costliest earthquake disaster in U.S. history.”
Utilizing their federal Quick Response dollars and implementing the expedited contracts allowed Caltrans to put more than 250 workers on the job in rotating 12-hour shifts – for a total of 10,000 labor hours – and reopen the highway in just eight short days, according to ENR.
Ben Walnum, Senior Project Manager for Griffith Company described the workload. “It was 24/7 for 72 hours.” Griffith Company was credited with shaving “two or three days” off the schedule due to their construction coordination and debris removal efforts.
Caltrans’ Hopkins credited the union construction crews for their “tireless… agile and flexible” work for returning the I-10 to service.
Did an Unusual Policy Contribute to the Disaster?
New discoveries made during the assessment, clean-up, and continuing reconstruction of the I-10 have placed a focus on the unusual practice of leasing space under and adjacent to highways throughout the state. A memo, sent to Gov. Newsom in February 2024 by Caltrans Director Tony Tavares, outlined suggested changes to prohibit the storage for highly flammable and chemically dangerous materials from the leased properties.
Caltrans currently leases 600 “airspace” properties with an estimated annual revenue of $35 million. The proposed changes may be due to the nature of the I-10 fire, which spread, in part, by burning hundreds of wooden pallets and stored chemicals at two storage facilities. The fires are alleged to have been arson and are still under investigation.
Processes, Innovation, and Outstanding Commitment
As noted earlier, the I-10 and I-95 collapses are not an apples-to-apples comparison. Rather, they provide valuable insights into how to mitigate the real and economic damage large-scale highway infrastructure disasters can cause to communities.
Process = Progress
Had the Northridge Earthquake not required extraordinary efforts in freeway rebuilding and given the state a process for awarding large-scale emergency contracts, California would have experienced a financial impact in the millions, if not billions, of dollars as citizens and commercial interests waited months until traffic flow was restored.
Further, the structural analysis and environmental investigation processes in both Philadelphia and Los Angeles, handled by local, state, and federal agencies, was completed in just a day or two because of the processes those agencies had in place for disaster management. And FEMA processes allowed the Quick Response funds to be allocated almost immediately after States of Emergency were declared by each Governor, providing financial incentives so that contracts could be secured in just hours, rather than days or weeks.
It's also important to note that the flexibility within each state’s processes allowed for rapid response relief because the DOTs of each state were free to hire the contractors closest to the site, or most able to mobilize quickly, which was especially important to the I-10 clean-up efforts.
Innovation Slashed Timelines
Most of the innovations reported in California were of the legislative or process variety, i.e., utilizing the 1994 Northridge contracts to speed repairs. In Pennsylvania, however, innovative planning, design, materials, and even late-stage processes, are responsible for slashing weeks of waiting from I-95’s comeback.
Led by the decision to utilize lightweight foamed glass aggregate rather than topsoil for embankment construction, and bolstered by the polyester geogrid reinforced walls, prefabricated parapet and moment slabs, Buckley Co., Inc. and PennDot were able to do in days what would normally have taken months to complete. The additional decision to bring in the NASCAR Track Jet Dryer to speed the final processes of asphalt and painting also cut days from the schedule, and frankly, lends a coolness factor to the project that at this point few can claim. Although that may change as word spreads about how it impacted the speed to reopening.
Committed Contractors & Outstanding Manpower Contributions
At the end of the day, all the innovation and processes in the world cannot pull off even the most basic highway repair without committed, experienced, and professional general contractors, subcontractors, and tradespeople. And when the stakes are as high as reopening major thoroughfares that carry nearly a half a million vehicles each day, that commitment can be tested: by policymakers, state officials, citizenry, and the media.
Governor Shapiro went so far as to install cameras at the site of the I-95 repairs with a now-famous public video feed so that people in Pennsylvania, and viewers throughout the country and the world, as well as the media, could watch the tireless work of team after team of contractors and laborers, as they, much like first responders, rescued travel, commuting, and commerce from disaster.
Tens of thousands of labor hours, day-in and day-out, in challenging and changeable conditions, are ultimately what rebuilt I-95 and I-10: the continual labor of the people who executed the plans, accepted innovation, and committed to get the job done.
That’s how you build anything – with professional, committed people.
