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Key Bridge collapse’s impact on Baltimore tunnels, I-95 traffic revealed in data

Cars and trucks have clogged Baltimore’s two interstate tunnels following the collapse of the Francis Scott Key Bridge, backing up traffic and slowing the speeds of area drivers, according to data analyzed by The Baltimore Sun and a private traffic management firm.

During the week ending March 30, Baltimore’s two remaining harbor crossings — the Fort McHenry and Baltimore Harbor tunnels — combined to handle over 9% more traffic than they did the previous week. That’s according to The Sun’s analysis of data it obtained from the State Highway Administration using Maryland’s Public Information Act.

Before the collapse, almost six out of every seven trips across the harbor were through one of the tunnels. But that still left more than 34,000 daily crossings of the Key Bridge for the tunnels and other routes to potentially absorb, according to Mansoureh Jeihani, who directs the National Transportation Center at Morgan State University.

The Fort McHenry Tunnel gained the most traffic following the bridge collapse. It carries Interstate 95 under the Patapsco River, is the innermost crossing of the harbor and is historically the busier of the two tunnels. Southbound traffic heading from Southeast Baltimore’s Canton neighborhood to South Baltimore increased nearly 12% in the week ending March 30 from the week prior, while northbound traffic increased by nearly 11%. In 2023, the increase in the same weeks was around 4.4% and 6.5%, respectively.

The Baltimore Harbor Tunnel didn’t see as much of an increase, but traffic still rose 7.5% northbound (the route heading from the Brooklyn neighborhood of South Baltimore to Canton) and 4.7% southbound. The Harbor Tunnel thruway is part of Interstate 895. It splits from I-95 to take a more westerly approach from the north and a more southerly approach from the south.

Traffic in both tunnels remained elevated more than three weeks after the collapse, which was the most recent period available when the data was requested.

Seasonal swings in traffic are normal, but only by a few percentage points, said Bob Pishue, a transportation analyst for INRIX, a traffic management and analysis company that tracked decreases in vehicle speeds in the Baltimore area from March to April.

The overall regional impact of the bridge collapse on traffic has been minimal, said Pishue, but INRIX’s data analysis shows certain areas have experienced slower travel times. The analysis uses anonymized GPS data to analyze how vehicles are moving.

Pishue said that while congestion can have many contributors, like crashes or weather, the disruptions being observed are likely due to the Key Bridge collapse.

“Trying to figure out how much of it exactly is — that’s probably a scientific paper of some kind,” Pishue said. “Because there’s so many factors.”

One of the hotspots noted by Pishue was southbound I-95 from Rosedale in Baltimore County to Washington Boulevard in the city, including the Fort McHenry Tunnel. The average speed of vehicles driving through the tunnel was as low as 21.6 mph at 7 a.m. in April. That’s a 59% decrease from the average speed of vehicles heading south through the tunnel at 7 a.m. in March.

In the evening, another hotspot has been northbound I-95 between Arbutus in Baltimore County and the Fort McHenry Tunnel. Average traffic slowed nearly 67% to 13.8 mph in the 4 o’clock hour from March to April in that section of the highway.

Michael Latona, 34, of Union Square in Central Southwest Baltimore, tried driving this stretch of I-95 for about two weeks when he started a new engineering job shortly after the bridge collapse. He gave up, switching to commuting via MARC train and a bicycle.

“The Thursday and Friday — the straw that broke the camel’s back — Thursday, it took me about an hour and 40 minutes to get home and then Friday it took me about 2 hours and 15 minutes to get home,” Latona said. From his office to his door, it’s an 18-mile trip.

Despite these problems, the full impact on traffic of the bridge collapse hasn’t been felt yet. That’s because truck traffic is still reduced, due to fewer ships being able to reach the Port of Baltimore. The Army Corps of Engineers hopes to restore normal port access by the end of the month.

“When the port opens and the bridge is not built yet — then we’re going to have even worse traffic,” Jeihani said.

How commuters respond to traffic is one aspect of research being undertaken by the University of Maryland and George Washington University along with Morgan State, which is to conduct a community survey of individual travel behavior.

Morgan State is also collaborating with the Maryland Department of Transportation and the State Highway Administration on possible solutions to glean from patterns in simulated traffic models. Researchers are using past data to simulate different scenarios.

“There are specific areas that we know people are going to reroute to,” Jeihani said. “But when those areas get more congested, people are going to reroute further and other places.”

One possible short-term solution is implementing ramp meters, Jeihani said. Used on Interstate 270 in Frederick and Montgomery counties, these are traffic signals on on-ramps that control how many vehicles enter. When Morgan researchers ran scenarios with three ramp meters on I-95 and three on I-895, each showed “signs of improvement.”

There are also solutions that can involve drivers and employers. Jeihani said people can help by not driving aggressively, by using transit and by ridesharing. Employers can set workers’ hours to avoid rush-hour commutes or allow remote work.

The U.S. Census Bureau released estimates May 8 that indicate around 4,600 car commuters living or working in Baltimore or Baltimore County likely used the Key Bridge, with about a third working in management, business, science or arts jobs and nearly as many working in production, transportation or moving of materials.