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Gregory Jordan, Center for Advanced Transportation Technology Laboratory |
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In January 2025, four wildfires driven by seasonal Santa Ana winds tore through coastal communities in and around Los Angeles. Two of these—in Pacific Palisades and in Altadeena, 25 miles to the east—ignited on January 7, just eight hours apart. That day spawned the most destructive wildfires in Los Angeles history, with the direct loss of 31 human lives and destruction of more than 15,000 homes, stores, and other buildings.
Afterwards, emergency planners in a nearby state with significant wildfire exposure asked University of Maryland (UMD) researchers to focus their highway traffic analysis tools and expertise to produce a record of roadway traffic patterns during those events—vehicle and people movement insights that can inform disaster preparedness planning for high-risk population centers.
UMD’s research tools, part of the Regional Integrated Transportation Information System housed at the Center for Advanced Transportation Technology Lab (CATT Lab), parse location data reported by connected vehicles in the traffic streams, and from sensors deployed along highways. These enable analysts to understand which evacuation routes were used and when; what speeds and travel times occurred along those routes; which detours were taken; and the severity of congestion along each. The underlying empirical data—anonymized, time-stamped movements of vehicles in traffic—were provided by INRIX, a transportation analytics company that has shared data with UMD since 2008 for projects with dozens of state and local departments of transportation.
Hard Data on Difficulties of Escape
By studying how traffic flowed along major arteries during these emergencies—through and around coastal bluffs of the Pacific Palisades community, or filtering through the traditional street grid of Altadeena, CATT Lab researchers were able to corroborate anecdotal reports of where the bottlenecks formed, while pinpointing the precise timing and spread of the conditions. The most significant findings contrast the relative ease with which evacuees could flee along the Altadeena street grid, compared to winding for miles through crawling queues across Pacific Palisades while the fires advanced.
The Palisades Fire, originating in the parched Santa Monica mountains just to the north, was driven by fierce winds along the ridgelines and into the communities. Gregory Jordan, an expert in people movement analyses at the CATT Lab, explains that “with the fires coming fast on one side and the ocean on the other, there just weren’t enough ways out.”
Evacuees living both to the north and south of Sunset Boulevard, the primary east-west arterial through the heart of town, had to converge on that road and then travel east toward Santa Monica, or west to join the Pacific Coast Highway. At the ocean, however, fire blocked travel farther west, forcing fleeing vehicles to turn back to the southeast. “It’s a factor of terrain, geography, and nature,” Jordan said. “You’ve got these hills with bluffs that keep the housing areas enclosed.”
The difficulty of escape has been documented in the CATT Lab data. For example, just two hours after smoke was first reported, traffic cutting through Temescal Canyon slowed to 9 mph, soon down to 6 mph during the next two hours. At 3:15 p.m., traffic stopped entirely on W. Sunset Blvd near Palisades Drive. This correlates with anecdotal reports of smoke, flames, and vehicles abandoned by panicked occupants fleeing on foot. After the immediate danger passed, responders were blocked until bulldozers pushed these cars aside, as recorded in the memorable videos shown by the media.
CBS News highlighted the CATT Lab/INRIX project in a recent story, “How the Palisades Fire zone turned into an evacuation nightmare,” which also included an interview with actor and local resident Steve Guttenberg, who helped save cars with keys left behind from the bulldozers.
Lessons Learned Could Spur Improvement
Emergency preparedness planning includes not only making predictions about where and why evacuation bottlenecks will form in emergencies, but in weaving those predictions into mitigation strategies and plans, Jordan said. These plans, in turn, must be agreed on, funded, and operationalized by law enforcement, first-responder, highway traffic management, and governmental & civic leadership groups.
To do this effectively, he said, analyses must be backed by provable facts. Models need real world data for their what-if analyses, and compelling stories need to be told to stakeholders and the public about the potential consequences of doing too little. “If there can be a beneficial side to the Palisades and Eaton Fire disasters, it will be in the motivating forces that come from understanding—and telling and showing—exactly what happened,” Jordan said.
April 14, 2026
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