How Tropical Storm Debby snarled Tampa Bay traffic

If you drove between St. Pete and Tampa early last week, you experienced it: traffic on our cross-bay bridges — especially the Howard Frankland Bridge — slowed to an agonizing crawl.

Why it matters: The jam was another product of Tropical Storm Debby's scrape past Tampa Bay, underscoring how much an indirect hit from a weaker storm can upend our lives and routines.

What they're saying: "Debby wasn't much of a storm," but still caused a storm surge that inundated roads, University of South Florida physical oceanography professor emeritus Robert Weisberg told Axios.

• "If we were to have an actual hurricane hit this region, it would be an actual disaster."

Driving the news: Debby brought a deluge of rainfall and gusty wind to Tampa Bay starting last weekend and continuing into last Monday.

• On the Howard Frankland, video shared by the Florida Highway Patrol showed waves thrashing the barrier wall and spilling onto the causeway.
• Early Monday, troopers learned part of the northbound shoulder had washed out in the storm, Sgt. Steve Gaskins told Axios.
• That led troopers to close all northbound lanes for much of Monday. The inside lanes later reopened, but the outside lanes stayed closed while workers fixed the shoulder.
• All lanes reopened about 4:30pm on Wednesday.

Yes, but: Commutes were miserable in the meantime.

By the numbers: On a typical weekday morning in July, it took about 6 minutes to drive over the 6-mile bridge, according to Florida Department of Transportation data.

• On Wednesday, while the two outside lanes were still closed, that drive time ballooned to about 31 minutes.
• The mid-day drive time tripled, from about 5.5 minutes to 17 minutes.

💭 Kathryn's thought bubble: It was so bad Wednesday afternoon (before the lanes reopened) that Google Maps recommended I go over the Skyway and up through southeast Hillsborough to get from south St. Pete to north Tampa.

• Somehow, that 62-mile trip was 15 minutes faster than the 36 miles it would take me to go over the Howard Frankland.

How it happened: A washout is sudden erosion from the foundation of a road being inundated with water.

• Debby brought about 3 feet of storm surge to Tampa Bay, bringing the water level almost as high as the road, Weisberg told Axios.
• The slopes next to the two washed-out areas were under construction and had only a temporary wall for wave protection, per FDOT spokesperson Kris Carson.
• Sections of the bridge with permanent walls were not damaged, she said.
• "We are confident the final construction will meet the standards for this type of roadway," she said.