Planning a Road Trip for the Total Solar Eclipse? Here’s Why You Should Drive Extra Carefully

Scientists found a 31 percent increase in fatal car crashes around the 2017 total solar eclipse, akin to spikes in traffic risk on busy holiday weekends

Traffic on highway
Traffic backed up on Interstate 57 near Johnston City, Illinois, after the total solar eclipse on August 21, 2017. Scott Olson / Getty Images

Millions of people are expected travel to see the total solar eclipse on April 8. And with many of them driving—clogging the roads with extra vehicles—scientists are warning of a potential uptick in fatal car crashes.

Their prediction is rooted in data from the last total solar eclipse that was visible from North America, which took place on August 21, 2017. On the day of that eclipse, along with the day before and the day after, scientists found a 31 percent increase in the number of fatal crashes per hour compared to non-eclipse periods, they report Monday in the journal JAMA Internal Medicine.

That’s one extra crash fatality every 95 minutes, for a total of 46 extra deaths linked to the 2017 eclipse. The increase is similar to what happens over busy holiday travel weekends, like Thanksgiving or the Fourth of July.

The surge in crashes likely has nothing to do with the conditions of the eclipse itself—drivers aren’t getting into accidents because of the sudden dimming of the sun.

Rather, the higher traffic risk is likely due to “increased traffic, travel on unfamiliar routes, speeding to arrive on time, driver distraction by a celestial event, drug or alcohol impairment from related celebrations or eclipse viewing from unsafe roadside locations,” says study co-author Donald Redelmeier, a physician and scientist at the University of Toronto and the Sunnybrook Research Institute, in a statement.

That theory is backed by the fact that the number of fatal crashes decreased during the hour when the eclipse was happening in 2017, reports Live Science’s Nicoletta Lanese.

“One of the surprises that I didn’t anticipate was that the risks do not occur at the exact moment of totality,” Redelmeier tells CNN’s Mira Cheng. “It’s not when everything is dark and black and chilly, but instead, they occur in the hours before and after.”

An estimated 20 million Americans traveled to see the 2017 eclipse, which had a 62- to 71-mile-wide path of totality, or the swath of Earth from which the moon appears to fully block the sun. Researchers were curious to know how all that travel affected fatal car crashes, so they dug into data from the National Highway Traffic Safety Administration’s Fatality Analysis Reporting System.

More specifically, they looked at the number of accidents that occurred the day before, the day of and the day after the 2017 total solar eclipse, from August 20-22. For comparison, they also pulled the same statistics for a three-day period the week before the eclipse, as well as a three-day period the week after: August 13-15 and August 27-29.

Using a U.S. Navy calculator, they also studied the latitude and longitude of each crash to see what time it occurred in relation to the local eclipse maximum, or the point at which the moon appeared to complete block the sun’s light.

They found that 10.3 fatal crashes occurred per hour during the three-day eclipse period, compared to 7.9 crashes per hour during the comparison periods.

The Moon and the 2024 Total Solar Eclipse

Drivers and passengers were most vulnerable after the eclipse, when the traffic risk rose to nearly 50 percent above average. The riskiest hour of the entire study period was between 6 p.m. and 7 p.m. on the evening of the eclipse, reports the National Post’s Sharon Kirkey.

“We’re especially concerned about the drive home,” Redelmeier tells Live Science.

The traffic risk was also higher in locations with clear skies, compared to those with overcast skies, the researchers found.

The study only looked at fatal crashes and did not consider other accidents with less severe outcomes. The scientists also could not distinguish between local drivers and tourists who were involved in accidents while traveling to see the rare celestial phenomenon.

This year, the path of totality is much wider than it was seven years ago. An estimated 31.6 million U.S. residents live within the path of totality for April’s eclipse, compared to 12 million in 2017. Still, the regions experiencing totality will receive a massive influx of tourists.

“Many first-time viewers will attend the 2024 eclipse because of what they heard from those who saw the eclipse in 2017,” wrote Jonathan Upchurch, a transportation engineering consultant and emeritus professor at Arizona State University, in the September-October 2018 issue of TR News, a publication of the Transportation Research Board. “The event also will have a high number of repeat participants.”

Whatever happens on April 8, the researchers recommend all drivers use extra caution and practice safe driving techniques, such as following the posted speed limits, wearing seat belts, signaling turns and limiting distractions.

“We all share the road, so just because you’re not paying attention to the eclipse, you have to pay attention to every other driver that surrounds you,” Redelmeier tells the National Post.

Eclipse viewers should also take precautions when they are watching the skyward spectacle itself. The primary risk is eclipse blindness, or solar retinopathy, which is caused by staring directly at the sun without eye protection. Anyone who wants to look up at the sun as the moon passes in front of it should invest in a pair of eclipse glasses. Cameras also need special solar filters for viewing or photographing the eclipse.

Don’t look directly at the partially eclipsed sun without the proper protection, says Hin Cheung, an optometrist at Indiana University, in a statement. “Photochemical damage is cumulative,” he adds. “Staring at the sun for short periods at a time does not protect you; the damage from each viewing adds up. This may cause temporary or even permanent changes to your central vision.”

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