An assortment of views on Friday morning of Seattle-area roadways as seen from Washington State Department of Transportation traffic cams. (WSDOT Images)

Average speeds on major roadways in the Seattle region were more than 10 mph faster than normal on Thursday morning, the first full workday after Microsoft, Amazon and other major companies instituted work-from-home policies amid the novel coronavirus outbreak.

The early numbers from INRIX, the Kirkland, Wash.-based traffic data and analytics company, suggest that many employees are heeding the guidance of their employers. The trend continued Friday morning, as traffic cameras showed smooth sailing on normally clogged arteries in Seattle and east of the city in Bellevue, Wash.

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“Based upon early returns of traffic data for Thursday, it appears travel speeds have increased by 50-100% with work from home policies,” INRIX said in an updated post.

However, the Washington State Department of Transportation wasn’t ready to call the trend statistically significant. Time of day, which direction you’re coming from, the weather and the same old driver mishaps all play a factor in traffic flow.

Earlier in the week, as some companies started encouraging workers to stay home, INRIX reported speeds 4 to 5 mph for the morning commute and 9 mph faster for the evening commute. Both routes that cross Lake Washington — I-90 and SR-520 — experienced significant increases in average travel speeds on Monday, INRIX said.

Traffic maps showed green lines extending around a region that is normally awash in red.

Images on social media Thursday captured roadways without the usual bumper-to-bumper stream of brake lights, and caused some to ponder a time before the tech boom transformed the region. Others wondered why telecommuting wasn’t more widely practiced.

INRIX data comes predominately from car-based GPS systems and mobile data. Travel speeds analyzed for Monday were calculated against average speeds from the six preceding Mondays on King County roadways such as Interstates 5, 405 and 90 and State Routes 520 and 99.

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Compared to sunshine on Thursday, rain and stalled vehicles in various spots on Friday managed to snarl things a bit, according to various tweets from WSDOT. Drivers heading south from northern points such as Everett saw easier commutes, while those coming up from the south end ran into trouble.

“We look at the range of what’s normal, high end and low end, and travel times have been lower,” said Bart Treece, a communications manager with WSDOT’s Northwest Region. “It’s too soon to see if it’s a trend,” he added, noting that sunnier weather and earlier light in the morning usually leads to better drive times. “People tend to drive slower when it’s dark and wet outside.”

(WSDOT screen grab)

WSDOT has a number of online tools for measuring traffic data. Users can select a date and display maps of Seattle area bridges, for instance, to try to better understand any particular moment in time and how things were flowing. The above map shows Friday morning at 8 a.m.

Regardless of coronavirus or regional work-from-home policies, Treece repeated WSDOT advice that could come at any time of year under any circumstance.

“It’s prudent for people to know before you go,” he said, noting that it doesn’t take much to jam things up. “Stay plugged in, check our mobile app, check Twitter.”

Post updated at noon Friday with latest INRIX data.

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