I-95 Collapse in Philadelphia Didn't Cause a Traffic Disaster, Data Shows

On June 11, a section of I-95 collapsed after a truck carrying gasoline flipped and exploded. The driver died in the crash and a section of I-95 was shut down. National news outlets predicted a traffic nightmare that would last for months, disrupt freight traffic, and create noticeable inflation across the country due to a supply chain crisis. 

Nothing unites American politicians like a highway in distress. State and federal politicians snapped into action, promising to deploy all available resources to fix the bridge to avoid an economic catastrophe. Transportation Secretary Pete Buttigieg called it “a major artery for people and goods, and the closure will have significant impacts on the city and region until construction and recovery are complete.” The Pennsylvania Department of Transportation set up a livestream of the repairs, which Pennsylvania governor Josh Shapiro says he’s “completely addicted to.”

Almost two weeks after the collapse, the bridge still isn’t fixed—although it will supposedly re-open this weekend in record time—but it is clear that those dire predictions did not come to pass. Initial surges in traffic in the Philadelphia area eased by the end of the week, according to data collected by HERE Technologies and Inrix, two transportation and mapping companies that use vehicle data to measure traffic flows. 

Apocalyptic gridlock did not ensnare the Philadelphia area. Truck traffic did not come to a halt. In fact, more people rode the train or took alternate routes and life marched on. A few key highway junctions are a bit slower than they were two weeks ago and traffic in the immediate area of the collapse remains thick. But the extent of the economic damage appears to be limited to things like local business owners not being able to have their lunch delivered to them.

“It appears through a mix of reasons, whether it’s people using public transit, workers working remotely, drivers figuring out better alternate routes, the congestion in the entire region returned to pretty close to normal by the end of this past week,” Kyle Jackson, a senior data analyst at HERE, told Motherboard. “It just took Philadelphia drivers a few days to figure out what those alternate routes were and adjust their commutes accordingly.”

Rather than being some shocking twist, this was an entirely predictable outcome. It is what happens every time a section of a major highway is closed, even unexpectedly due to an emergency. In 2017, a section of I-85 in Atlanta collapsed. The ensuing commute was “not so horrible.” In 2007, a bridge along I-35W in Minneapolis collapsed, but subsequent analyses showed its impact on travel times was minimal. There are many more examples of anticipated “carmageddons” not materializing for planned closures of major highways due to construction, such as the OG “carmageddon” in Los Angeles and the 90,000 cars that “just disappeared” off of the roads daily when the Seattle viaduct was closed. 

This is because of the well-established phenomenon known as induced demand. Most commonly, induced demand is invoked when new highways are built and within a few weeks, months, or years become as hopelessly clogged with just as much traffic as there was before. But it also works in reverse, when highways are taken out of commission and there is no noticeable long-term increase in traffic on nearby highways. It is especially true when there are several options to absorb additional traffic.

This is especially the case for I-95 through Philadelphia. And it’s why the national calamity narrative never made sense. This is a local news story that fearmongers suggested was a metaphor for America's crumbling infrastructure and would cause massive nationwide problems. As anyone who has driven along that section of the 95 corridor knows, through traffic does not travel along that particular section of highway. Despite I-95 running from Maine to Florida, the interstate route in the Philadelphia area runs via 295 or the New Jersey Turnpike on the New Jersey side of the Delaware River from Wilmington to Trenton, bypassing Philadelphia altogether. The section featuring the highway collapse, which is called the Delaware Expressway, is mostly a commuter road from North Philadelphia and suburban counties north to downtown. It also serves noted North Philadelphia landmarks like Four Seasons Total Landscaping.

Initially, the bridge collapse created “a severe spike in congestion” the Monday after the crash, according to Jackson. The highways in the entire Philadelphia area saw roughly double the normal congestion. But, as the week went on, people adjusted their travel behavior. The regional transportation system, SEPTA, saw a 14 percent increase, or about 1,000 more riders per day, on the three regional lines serving the affected area the Tuesday and Wednesday after the bridge collapse versus a week prior. Other drivers took detours. Some likely worked from home instead. By the end of the week, Jackson said, traffic in the region returned to “close to normal.” 

A separate study by Inrix, a traffic management and analysis company, found a handful of “hot spots” along some of the alternate routes where traffic speeds declined by at least 25 percent during rush hours, although that is based on a rolling average for the entire week so doesn’t fully account for the normalization of speeds as the week went on. 

While a few hot spots remain like the Pennsylvania Turnpike in the evenings and the local roads in the one-mile vicinity of the collapse, for the most part the traffic hell never materialized, said Bob Pishue, an analyst at Inrix.

“At the end of the day what you see is normal behavior,” Pishue said. “Travel dispersing, people changing modes or working from home or not making trips or consolidating trips. They’re making changes to their travel habits to adjust.”

What is most striking about the emergency response to what ended up being a local inconvenience is the sharp contrast to when something similar happens to anything other than a highway. For example, Amtrak’s second-busiest route, from San Diego to Los Angeles and up to Santa Barbara, has been cut in half, requiring replacement bus service, for more time in the last two years than it has been functioning properly because of erosion near the tracks. This has received virtually no attention from politicians or the media outside of southern California, even though the route normally runs 26 daily trains and has an annual ridership of some three million trips. Boston’s transit system has been plagued by slow speed orders, which is essentially bureaucrats ordering trains to behave as if they’re stuck in traffic, delaying commutes by 20 minutes or more each way for hundreds of thousands of people, again to little attention outside of the Boston area. 

Pishue says part of the all-hands-on-deck response to highway collapses is the declaration of a state of emergency which removes red tape to allow urgent repairs to be conducted quickly. Initially, Shapiro, Pennsylvania’s governor, braced locals for the highway to be closed for months. He is now taking a victory lap because it will reopen to traffic this weekend instead.

“So the lesson is why don’t we apply some of these same things to the other projects?” Pishue said. “And I think that’s a completely fair question.”