An estimated 250,000 cars use the Atlanta interstate, which is currently closed indefinitely. That’s similar to the traffic volume on parts of Seattle’s Interstate 5.
Atlanta drivers, we feel for you.
Not too long ago, Interstate 5 in Seattle closed due to a propane-truck crash, causing massive traffic gridlock throughout the region and frustrating commuters who were stuck in traffic for hours.
But that closure didn’t even last a full day.
Who knows how long people will live this traffic nightmare in Atlanta after a fire Thursday evening caused an interstate bridge to collapse, closing the major artery indefinitely, according to officials. Three people have been arrested in connection with that fire.
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As part of Traffic Lab’s series of Q&A’s, we’ve flipped the script to ask our own questions this round, spotlighting the massive transportation crisis in Atlanta.
We talked with DeWayne Wilson, a Washington State Department of Transportation bridge-management engineer, and other WSDOT staff members.
Here’s what they had to say:
Q: An estimated 250,000 cars use the Atlanta highway each day, which is similar to the average vehicle traffic on parts of Interstate 5 in Seattle. Where could those hundreds of thousands of commuters go if our roadway closed indefinitely?
A: Meditation classes, or some other way to cope with the traffic stress.
Because no matter what, since I-5’s traffic volume is higher than any alternative route, delays would be a guarantee.
Highway 99, Interstate 405 and Highway 509, for instance, would max out quickly, WSDOT spokeswoman Lisa Van Cise said in an email. The “big key” would be drivers staying off roads or delaying trips, she said.
In February, traffic paralyzed the Seattle area when the semi carrying propane rolled over on I-5, prompting an emergency response that closed the freeway for eight hours. Congestion spilled to surrounding streets as drivers attempted alternative routes.
So, if I-5 closed for a repair project like Atlanta’s, expect a similar traffic mess — only one that lasts weeks, or even months.
Wilson speculates that crews in Atlanta will install a temporary fix to the bridge within a few weeks, just to get traffic rolling. Then, he guesses they’ll return to make more permanent repairs.
That’s how crews approached the 2013 I-5 bridge collapse into the Skagit River, Wilson said. The roadway remained closed for roughly 30 days while crews made initial repairs.
Q: Could this type of collapse happen here?
A: Yes.
“It could potentially happen anywhere,” Wilson said. “It’s definitely a risk.”
For instance, a large train fire near the Puyallup River threatened a Highway 509 overpass in 2002, destroying some of the bridge’s concrete and temporarily closing traffic.
That Washington bridge is built much like Atlanta’s damaged one, with prestressed concrete that contains steel reinforcing bars, he said.
But Thursday’s fire seemingly burned closer to the bridge compared to the Washington incident, Wilson said. The closer the blaze, the greater the bridge damage.
In terms of structural threats, the 2002 train fire was extreme.
Transportation officials routinely stop traffic for vehicle fires, or firefighters sometimes head to homeless camps for blazes near major roadways, such as Seattle’s The Jungle under I-5. Bridge inspectors join those calls, too.
Fires aside, inspectors recently assessed potential damage on Interstate 405 after a semi rolled on March 15, Van Cise said.
“If it’s deemed unsafe, whether because the bridge was hit or there was a fire, we’ll send our inspectors there,” she said.
Q: In those types of emergency assessments, what do inspectors look for?
A: For fires, they first check for smoke damage, Wilson said.
Then, they see if the blaze was hot enough to cause moisture within the bridges’ concrete to boil or cause damage to the steel bars, he said.
“Once you get superheated, those things will yield and bend and get out shape,” Wilson said.
Those emergency assessments get mixed in with bridge inspectors’ routine checkups.
According to 2015 data by the National Bridge Inventory, 56 of King County’s 1,195 classified bridges have at least one defect, classified as “structurally deficient.”
That’s 4.8 percent higher than the national average, according to a nationwide analysis by The Washington Post.