• As the US looks to reopen after months of lockdown, cities may face unprecedented levels of congestion if commuters avoid public transit and drive to work instead.
  • Due to increased car traffic from commuters who previously rode public transit or carpooled, cities may see 100% or more of their traffic return after only a partial reopening, one expert told Business Insider.
  • Recent surveys have shown that confidence in public-transit systems has dropped, while interest in buying cars has increased.
  • Visit Business Insider’s homepage for more stories.

As the US gradually emerges from lockdown, workplaces reopen, and restrictions ease, cities will need to contend with a challenge they haven’t regularly faced in more than three months: traffic.

According to some experts, traffic in US cities won’t simply snap back to pre-pandemic levels – instead, congestion may rapidly balloon to heights never seen before. Due to fears of contracting the virus, huge numbers of commuters who had previously opted for public transit may take to the streets, whether that’s in their personal cars, in ride-shares, or on bikes.

“The problem is going to be that all these forms of transportation are competing for the same amount of finite space,” Sam Schwartz, a transit consultant and former New York City traffic commissioner, told Business Insider. “Even at 50 or 60% of a full reopening of a city… what we’re going to see is perhaps 100% or more of automobile traffic.”

Schwartz – known as “Gridlock Sam,” since he’s credited with coining the term “gridlock” – said previous transit riders who have the option to drive will account for some of the new congestion.

"And if we follow the stupid advice of the CDC to drive alone in your car, we'll even have the carpoolers," he said, referencing the Centers for Disease Control and Prevention's recently released guidelines that encourage commuters to avoid mass transit and carpooling.

A recent survey from research outfit Elucd found that 44% of New Yorkers, for example, will avoid public transit after quarantine ends, and that another 31.5% plan to use mass transit less by walking, driving, or biking. Nationwide, the poll found that 45.8% of people will "avoid transit entirely."

Not to mention, according to a global survey cited by the Detroit Free Press, the pandemic has led to an overall increased interest in car ownership, including among younger buyers and those who have never owned a car before.

And a new study from Vanderbilt University titled "The Rebound: How COVID-19 could lead to worse traffic" further backs up Schwartz's claims. Researchers modeled out scenarios in which straphangers and carpoolers begin commuting by personal car instead of returning to their old habits. According to the paper, "Cities that depend on transit are at risk for extreme traffic unless transit systems can resume safe, high throughput operations quickly."

At-risk cities include San Francisco, where daily commute times may increase by 20 to 80 minutes per person for a round trip. New York, the study concluded, may see roughly 1.2 million to 5.8 million added traffic hours per day, the equivalent of 14 to 68 minutes added to each commuter's round trip. In Boston, round-trip commute times could increase by 6 to 22 minutes per person.

Without new policies such as vehicle-occupancy restrictions and congestion pricing, the number of vehicles in New York, for one, "could grow to levels we've never seen before short of transit strikes," Schwartz said.

"We have a real risk of gridlock as traffic goes to levels well over 100%," Schwartz said. "And when traffic was at 100%, we were moving at 4.7 miles per hour in midtown Manhattan, which is not tolerable for the long term."