Brenna Swift, The Union Democrat

A tour bus carrying more than 30 sixth-graders was stranded on a remote one-lane dirt road in Yosemite National Park over the weekend after the driver got wrong directions from a GPS mapping device.

The 44-foot-long bus got stuck on a hairpin turn Friday night on Foresta Road. It stayed there until Sunday night, when a truck from Vic's Towing in Sonora arrived.

The passengers were on their way into the park for a NatureBridge program in Crane Flat for the weekend. NatureBridge is a San Francisco-based program that introduces urban children to the outdoors.

They arrived at their destination safely around 8 p.m. Friday, shuttled there by parents and teachers who had been driving their own cars, said Kristina Rylands, director of NatureBridge Yosemite.

Foresta resident and seasonal ranger Noreen Trombley said the bus's plight came to her attention when another Foresta resident saw the students walking along the road, their path lit by flashlights.

Rylands said they didn't have to walk far, just to a spot where the parents and teachers could pick them up. NatureBridge later sent a pickup truck to the bus to retrieve their luggage, she said.

NatureBridge supplies teachers with detailed directions to locations in the park. The tour bus had been heading east on Highway 120 when it breezed "right past" Crane Flat. The driver somehow ended up going down Foresta Road, Rylands said.

Foresta is a small community on private land within the boundaries of Yosemite National Park, at its far western edge. Foresta Road starts near the town and continues to El Portal.

The tour bus was owned and operated by the San Francisco-based Alma Mater Inc., which did not return a call for comment for comment Monday.

It appears to have gotten stuck on the hairpin turn at McCauley Meadow after the driver tried turning around, then backed the bus's rear off the edge of the road and caught the undercarriage on the dirt.

Yosemite National Park's towing service tried and failed to remove it.

"The end result was that they just didn't have a big enough truck," said Scott Selesia, a co-owner of Vic's Towing.

The tow company sent down a truck capable of hauling more than 16 tons and finished the job Sunday night, backing down the road for about a half mile to reach the bus.

Trombley said drivers often follow GPS directions down the road, only to discover that it's too rough and narrow.

"We get the problem all the time with cars and smaller tour buses," she said. "This is the first time it was a tour bus that big."

The number of drivers attempting Foresta Road increased about six years ago when GPS units became more common in rental cars, said Trombley, who has lived in Foresta since 1981.

GPS units will sometimes select Foresta Road as the route to El Portal and the valley floor.

On one summer day, when she was working to remove invasive plants near the road, she counted 32 cars going down it over the course of a few hours - then heading back up after their drivers realized the mistake.

"We see them coming back up scared, with white knuckles," Trombley said.

She said Foresta residents have been asking Yosemite National Park to put directional signs at each end of the road, guiding drivers back along the main route to the valley or to San Francisco.

As it is, signs show the letters "GPS" crossed out and advise drivers that it's not a practical road, Rylands said.

Trombley suggested that visitors use the maps provided at the park's entrance gates instead of their GPS units.