Many state departments of transportation are launching intensive communications efforts and planning how their operations teams will handle a potentially huge travel-disrupting event that is just a month away – the Aug. 21 daytime solar eclipse that will have the moon totally block the sun across parts of 14 states.

Those and other agencies warn that the eclipse could trigger major traffic jams, possibly lead to more traffic crashes, spur more human-caused wildfires at the height of fire season and potentially cause permanent eye damage to viewers including motorists who do not take proper precautions.

“Transportation often isn’t the first thing that comes to mind when you mention the eclipse,” said Matt Hiebert, assistant director of communications at the Missouri DOT. “But when you think about the number of people traveling to witness the event, maybe it should be.”

Hiebert is heading a multistate, eclipse-focused task force for TransComm, the committee for state DOT communications professionals at the American Association of State Highway and Transportation Officials.

He told the AASHTO Journal that the goal of the TransComm task force “is to unify messaging and make sure states have the resources they need to communicate the transportation impact of the event. The state DOTs have different levels of staffing, different priorities and access to resources. We wanted to reinforce message consistency about this important even, but we also wanted to help out the states who need the extra resources.”

State DOTs are usually experienced at managing isolated special events in a specific area, but this eclipse is a fast-moving event that is going to cross all kinds of jurisdictional boundaries – cities, counties, states and regions. That makes it a unique event, and one that could post an unprecedented set of traffic challenges as it shifts across the nation.

The transportation-related risks spread far beyond the 14-state “totality” zone where the sun will be completely blacked out for a couple of minutes in each area. The complete eclipse will last about three hours in each spot, and many states could feel the disruptive impact much longer as the eclipse moves through communities within their borders.

People in states well outside that zone will be able to see much of the eclipse, and their reactions could also affect roadway travel. A 50 percent solar eclipse is projected to be visible as far away as southern Texas and northern Maine. 

This will be the first total solar eclipse seen in the United States since 1979, and the first visible from coast to coast since 1918.

In many states the hospitality industry is marketing the event ​with special destination offers, including hotel or campground packages, parties and festivals. Those offers range far outside the total eclipse area, and venues are reportedly booking fast. 

“Some estimates show that 200 million people live within a day’s drive of the path of totality,” said Hiebert. “Millions of them are expected to travel to see it, and some states are predicting an influx of up to 2 million out-of-state visitors.”

Transportation departments see plenty of ways eclipse viewers could strangle normal traffic routes, in addition to the sheer numbers of extra vehicles.

For instance, if motorists slow down to glimpse it as they drive or pull off to the sides of busy highways, they can clog traffic and perhaps trigger crashes. Even those pulling into designated viewing areas could be stuck for hours once the eclipse begins.

And there are special risks. Many motorists will know to avoid looking directly at the eclipsed sun without special protective glasses, but some will not. DOT communications teams are also pressed to make sure drivers know not to operate vehicles with such eyewear.

Hiebert said the TransComm task force first met in April and found a wide variation of state preparations. “Some had been talking about the eclipse since last fall, while others were just getting off the ground,” he said.

Since then, states have shared messaging tools including social media graphics, a prototype press release, a draft communications plan, potential language for on-highway message boards and general talking points for state DOT officials. The task force is also working with the Federal Highway Administration on the effort, he said, plus other AASHTO committees, the National Operations Center for Excellence and the Society of Broadcast Journalists.

The total eclipse zone will enter the continental United States at Oregon’s western border, move in a downward arc across the West, Midwest and South, and exit through South Carolina.

Along the way, the totality will also touch – in chronological order – Idaho, Montana, Wyoming, Nebraska, Iowa, Kansas, Missouri, Illinois, Kentucky, Tennessee, North Carolina and Georgia. The FHWA has been spreading the word on a special website that includes a map of the totality path from the National Aeronautics and Space Administration. 

“In the area of the path of the total solar eclipse,” the NCDOT said in its own website notice, “daylight will fade like dusk, go to darkness and then have a dawn-like experience in the middle of the day.” It is among state DOTs that will suspend highway construction projects for days around the eclipse. 

The Idaho Transportation Department, a high-altitude state in the totality, said that “estimates are for tens and even hundreds of thousands of people to descend on Idaho. Some projections put the migration at more than one million.” The ITD said it is “developing an incident-response plan, identifying locations that may become bottlenecks and developing traffic-control plans.” 

MoDOT has a website with a countdown clock to the eclipse, and says an extra 1.2 million people are expected to visit. It advised motorists “to expect heavy traffic on Missouri’s interstates and all roads inside the area of the total eclipse on Monday, Aug. 21. Extreme congestion is expected once the eclipse passes in the afternoon. Viewers of the eclipse should leave early for their viewing location, stay put and then leave late to avoid the heavy congestion.” 

The Oregon DOT has a particular worry, since the event is coming at the peak of that state’s fire season, is projected to draw one million visitors to Oregon and 70 percent of wildfires are caused by people. “The odds are not in our favor,” ODOT said, in a press release that gave tips on reducing the fire risk. 

Map courtesy NASA, shows the path across the country where the total solar eclipse will take place.​