DALLAS (CBSDFW.COM) – As the COVID-19 pandemic forced many people to stay home, across North Texas traffic volume went down.

Fewer cars on the road this year led to fewer accidents, however, a CBS 11 I-Team analysis of state crash data found a “surprising” and deadly trend.

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While the number of crashes are down, the number of people killed on the roads in North Texas has gone up.

Since March in Dallas, Tarrant, Collin, and Denton counties, 480 people have been killed on roads according to state crash records.

That’s 72 more deaths than during the same timespan last year.

“It’s a very interesting phenomenon,” said Robert Wunderlich with the Texas A&M Transportation Institute. “We were surprised to see that. What you would like to see is a proportional decrease in serious crashes in conjunctions with the decrease in total crashes.”

As Wunderlich and his team of traffic engineers studied crash records from around the state, they discovered the reason for the increase in fatal wrecks was speed.

With less congestion on the roadways this year, drivers had the opportunity to travel faster and they did. So when crashes happened, they were more likely to be fatal.

Wunderlich said this unintended consequence to less roadway congestion could change the way engineers approach reducing traffic in the future.

“We have to find a way to reduce the risk of faster travel,” he said.

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In May, 53-year-old Alvaro Torres was driving home from a construction job when his dump truck was struck by a speeding SUV on Central Expressway in Plano.

According to police, the 32-year-old driver of the SUV was “speeding over the limit” when he ran a stop sign, crossed a grassy median, went air-born, and then flipped over a concrete barrier striking Torres’ truck.

Torres and the driver of the SUV were killed.

Deadly crash on Highway 75 in Plano. (Chopper 11)

According to the crash report, cocaine and fentanyl were found in the driver’s system.

“People don’t think about car crashes until it happens to a person they know,” said Torres’ son, Alvaro Jr. “There are speed limits for a reason. People need to follow them.”

Speed is not the only risky driving behavior that’s increased during the pandemic.

According to a federal report that looked at data from emergency rooms, since the start of the pandemic nearly 65% of drivers involved in serious and fatal wrecks had alcohol or drugs in their system.

Before the pandemic, 50% of drivers in serious crashes had drugs or alcohol in their system.

The report from the National Highway Traffic Safety Administration notes “drug prevalence was high among seriously and fatally injured roadway users before the public health emergency began and was even higher during, especially for alcohol, cannabinoids (active THC), and opioids.”

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