PHOENIX – When a highway closes or you’re just looking for possible routes, it’s natural to consult a navigation app or GPS unit. But drivers need to apply common sense to a computer’s suggestions, starting with not taking buses and other vehicles that aren’t up to the task down unpaved roads.

Since State Route 64 closed due to heavy snow between Grand Canyon Village and Grand Canyon National Park’s east entrance, a large bus, a smaller bus and at least two passenger vehicles carrying tourists have gotten stuck on a forest road heading east from US 180 between Valle and Flagstaff toward US 89.

While tow trucks were able to free the other vehicles free and get them headed back to US 180, the Arizona Department of Public Safety, with help from an Arizona Department of Transportation snowplow, had to rescue 45 people from the tour bus as Monday’s snowstorm moved in. The driver of the bus, which was bound for Page, said his GPS unit recommended taking the forest road.

The Coconino County Sheriff’s Office receives many calls throughout the year from motorists who get stuck following suggested alternate routes onto unpaved roads. It’s a big concern for ADOT during the winter, when snowstorms can cause sudden and prolonged highway closures.

“Sticking to the main highways is a driver’s best bet, especially during snowstorms,” said Audra Merrick, district engineer for ADOT’s North Central District. “Our snowplow crews are out clearing these roads around the clock along with patrols from the Department of Public Safety and ADOT’s motor-assist vehicles. Don’t follow an alternate route that’s not regularly plowed during winter storms.”

Earlier this winter, a Pennsylvania family wanting to see Grand Canyon National Park’s North Rim got stranded following forest roads suggested as an alternate route to State Route 67, which closes for the winter along with park facilities. A woman suffered frostbite walking 26 miles trying to get help, while her husband eventually was able to call rescuers by climbing high enough to get a cellphone signal.

Sgt. Aaron Dick, search-and-rescue coordinator for the Coconino County Sheriff’s Office, said if a suggested road becomes rough or difficult to navigate the best thing to do is turn around. Motorists also can prevent problems by understanding the settings on their GPS units or navigation apps, starting with making sure they are ranking alternate routes by “shortest time” rather than “shortest distance.”

“The shortest-distance setting will connect roads in the GPS unit’s inventory to create the shortest route without knowing the status or condition of the roads,” he said. “The shortest-time setting will generally keep the driver on paved or well-maintained roads.

Drivers heading to northern Arizona should do their research on road conditions by checking az511.gov and ADOT’s social media accounts on Twitter (@ArizonaDOT) and Facebook (facebook.com/AZDOT). They also should consult ADOT’s tips for winter driving at azdot.gov/KnowSnow, including:

• Tell someone where you are going, your intended route and your expected arrival time.
• Bring extra clothing and gloves, make sure the gas tank is half to three-quarters full at all times, keep cellphones charged, and pack extra drinking water, snacks and all necessary medications.
• Pack an emergency kit that includes blankets, a flashlight with extra batteries, an ice scraper, a small shovel, a container of sand or cat litter for traction and warning lights or reflectors.