Sheltering in place had one positive $1 billion side-effect for California

An aerial view from a drone shows an empty Interstate 280 on March 26, 2020 leading into San Francisco, California. With millions of San Francisco Bay Area residents under order to shelter in place due to the COVID-19 outbreak, few cars are on the roads. less An aerial view from a drone shows an empty Interstate 280 on March 26, 2020 leading into San Francisco, California. With millions of San Francisco Bay Area residents under order to shelter in place due to the ... more Photo: Justin Sullivan, Getty Images Photo: Justin Sullivan, Getty Images Image 1 of / 47 Caption Close Sheltering in place had one positive $1 billion side-effect for California 1 / 47 Back to Gallery

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The statewide order to shelter in place that went into effect on March 20 had a beneficial side-effect: Accidents, injuries and fatalities on California roadways were cut in half, saving the state and residents of California $1 billion, according to a UC Davis study.

In the 22 days after the shelter-in-place order (March 21-April 11), there was an average of 450 vehicle collisions per day throughout the state, according to the study conducted by the Road Ecology Center at UC Davis. During the same period in 2019, there were 1,128 collisions per day. In the 22 days prior to sheltering in place, there were 1,056 accidents per day.

“The reduction in traffic crashes, injuries and fatalities is a bit of a silver lining for people who are staying at home and who are impacted by the pandemic,” said UC Davis Road Ecology Center director and project lead author Fraser Shilling.

"The reduction in numbers of all collisions, injury, and fatal collision was equivalent to a $40 million/day savings in costs and about $1 billion in savings since the Governor’s order went into effect," the study concluded. The figures were calculated using Federal Highway Administration data, which includes savings from "property damage, treatment of injuries, lost time at work, emergency responses, insurance claims, and the equivalent cost of a life."

Not surprisingly, the study found that traffic volume decreased 20% to as much as 55% on freeways monitored by Caltrans.

"There is no equivalent in our recent transportation history to such large changes in vehicle movement on our state and local roads," the study said. "One outstanding question is: Why are so many people still driving on what may be non-essential trips?"

The decrease in traffic volume and accidents is the reason why California ordered some auto insurance companies to refund premiums for March and April, and possibly beyond if the shelter-in-place order is extended.

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Matthew Tom is a Homepage Editor at SFGATE. Email: mtom@sfgate.com.