As everyone readjusts to leaving the house more often and perhaps going back to work, they may not feel safe riding public transit or carpooling for a while, which could make for some ugly commute experiences for months to come.

That's the prediction being made by a study out of Vanderbilt University's Work Research Group.

"As communities begin to reopen, it is important to understand how quickly traffic will rebound," the study authors write. "Using basic laws of traffic, we can predict the amount of traffic that will occur in each city given only the number of vehicles on the road. This allows us to explore 'what if' scenarios."

The study looks at San Francisco, San Jose, New York, Los Angeles, Boston, Chicago, and Seattle. And because of San Francisco's relatively heavy dependence on transit and the fact that 3 out of 4 transit users here also own a car, we fare worse in these forecasts, with commuters seeing anywhere from 20 to 80 extra minutes sitting in traffic.

The scenarios are all working from 2018 traffic data as a baseline, and in that year the average SF car commute was around 35 minutes.

If 1 out of 4 transit users in SF decide they're going to start going to work by car, that could mean 10 extra minutes in commute times. If 3 out of 4 transit users opt for cars, they're looking at average commutes of 75 minutes or more. And if all transit users suddenly switched to cars, commutes would climb to 98 minutes or more.

"The most extreme scenario (when all riders switch) is extremely unlikely," the researchers write. "But it does illustrate that keeping transit open, safe, and available will be important to control the traffic rebound."

BART ridership has reportedly been down 90 percent during the pandemic lockdown, with the remaining 10 percent primarily being front-line healthcare workers and others who have to commute to other essential workplaces.

As things slowly begin to reopen, we'll see how many people opt for BART — and the SFMTA hasn't even given a date for when the Muni Metro might reopen. But given how slowly the Bay Area is expected to reopen businesses — and how many people are unemployed and how many companies will likely allow remote working for months to come — the "carmageddon" scenarios here could be quite a ways off.

Photo: Joel Danielson