The highly contagious and rapidly spreading coronavirus brought a major change in Twin Cities commuting behavior last week as motorists drove a lot less and those who did arrived at their destinations more quickly.

Research from the global traffic-tracking company INRIX found that speeds on metro highways and freeways were 25% faster during Wednesday's morning rush hour and 38% faster Wednesday evening when compared to the week before, when schools were shuttered and employees were encouraged to work remotely.

Even notoriously traffic-choked arteries such as the I-494 Bloomington strip, I-35W in Minneapolis and I-94 on both sides of the Lowry Hill Tunnel saw big performance improvements, said Brian Kary, MnDOT's director of traffic operations.

MnDOT's analysis of data collected from sensors and cameras placed along 400 miles of highways and freeways showed that on Tuesday, for example, motorists collectively logged 30 million miles, a drop of nearly 20% from the week before.

Fewer vehicles meant commuters encountered free-flow conditions more often than bumper-to-bumper traffic between 5 and 10 a.m. and between 3 and 7 p.m. In turn, that led to higher speeds and faster trips.

"Congestion was pretty much nonexistent," he said. "It looked like a weekend on a weekday."

What happened in the Twin Cities mirrored what happened in other U.S. cities. In gridlocked Chicago, average speeds during Wednesday's morning drive time were 77% faster when compared to normal. In traffic-choked Los Angeles, motorists moved 53% faster than normal, according to INRIX's analysis of commuting patterns in the 25 largest U.S. cities.

"Every major metro in the United States is now experiencing significant changes in average travel speeds during the peak commute hours due to COVID-19," said INRIX transportation analyst Trevor Reed.

MnDOT defines congestion as when traffic moves at 45 mph or less. Using that standard, MnDOT last year found that drivers in the Twin Cities were caught in congestion 25% of the time during morning and afternoon rush periods, the highest level since MnDOT began tracking traffic flow in 1993.

There is no telling if employees who are working at home amid COVID-19 concerns will continue to do so when things return to normal.

But if that happens and wide open roads become the new norm, "that would be nice," Kary said.

Construction will go on

Shutdowns related to the coronavirus are not expected to affect MnDOT's 2020 road construction plans.

Among the first projects scheduled to begin is a new roundabout that will be built at Hwys. 13 and 21 in Prior Lake. Work is set to begin March 30.

"MnDOT construction projects are moving forward as planned," said spokeswoman Chris Krueger. But given the quickly evolving situation and unknowns about COVID-19, "we remain in close communication with our contractors so we can be prepared and plan ahead for any impacts that may arise."

One thing that won't be happening is the Stillwater Lift Bridge "Lift & Loop" celebration May 15 and 16. A new date for the event will be determined within the next few weeks, said MnDOT spokesman Kent Barnard.

Follow news about traffic and commuting at The Drive on startribune.com. Got traffic or transportation questions, or story ideas? E-mail drive@startribune.com, tweet @stribdrive or call Tim Harlow at 612-673-7768.