Tioga Road in Yosemite National Park has 23 avalanche zones.

One man died clearing it in 1995, when an avalanche crashed down on his bulldozer.

Even without avalanches, accidents are common when the path stayed open for Christmas in 1977, more than 40 were reported in 24 hours.

That same year one of record drought the road opened five days after the annual spring plowing began. Still, sketchy weather prompted 22 closures between mid-April and July 4.

The clearing of Tioga Road, a stretch of Highway 120, has been an annual spring rite in Yosemite since the early 1900s. The highest automobile pass in California, it connects Lee Vining and Mammoth Lakes with Yosemite's Crane Flat before leading west to Groveland.

When it's open, about a quarter of the park's guests come through the Tioga Pass gate. An early clearing means added revenue for eastern Sierra towns, and a late one digs into the pockets of business owners.

But it wasn't until the bulldozer driver was killed by an avalanche in 1995 that the National Park Service realized how lucky its crews and operators had been.

"We thought we were very safe," said Kevin Cann, deputy superintendent for Yosemite.

But 1995 was a year of big snows, following six years of drought.

"In that amount of time, we seemed to forget the process for clearing big amounts of snow," Cann said.

The most dangerous site

Barry Hance was 43 when an avalanche struck the bulldozer he was driving at Olmsted Point. The foreman for the road crew in Yosemite's Mather District, Hance lead the effort to open the highway for 12 years.

Olmsted Point is popular with summer tourists who can stop for a snack while taking in the backside of Half Dome. But road crews regard it as the most dangerous site in their yearly plowing of the byway connecting the Eastern Sierra with the rest of the state.

Slick granite rock next to the road at Olmsted Point angles about 35 degrees and faces south leaving the site ripe for avalanches.

The patches that accumulate there don't look big. But one cubic feet of snow on that face weighs about 45 pounds. When it falls, it's comparable to a rockslide.

That's what happened June 13, 1995, when Hance was in his bulldozer directly underneath it. Four-foot-deep patches of snow had accumulated on the face. Warming rock melted the bottom layer, causing it to slide.

The far lane had been plowed, and the avalanche toppled the bulldozer off the snowpack and into the cleared lane, burying both vehicle and driver.

"It was frantic," recalled Yosemite Roads Supervisor Bob Brantley, a 25-year veteran of clearing Tioga Road.

Despite quick moves by the rest of the plowing crew to uncover him, efforts to revive Hance were unsuccessful.

"He loved Yosemite"

The accident still stirs emotion in the Park Service.

Each year one person in Yosemite earns the Barry Hance Award, a $2,500 honor given to the person who best exemplifies Hance's spirit.

"He loved Yosemite and he loved everybody who worked here," said Cann, who counted Hance among his good friends.

Cann was the Yosemite division chief of maintenance the year of the accident.

If Hance told his crew to be there at 5 a.m., the foreman would show up at 4, Cann said, and still have a smile on his face.

"He knew how to get people to work and have a good time doing it," Brantley said.

Cann said some theorize that Hance knew the danger at Olmsted Point that day, and therefore lead the plowing himself.

While Hance's death was a tragedy, most in the Park Service say agency officials have learned all they could from the situation.

Cann boasts that Yosemite now employs some of the best avalanche technicians and safety precautions in the world.

Avalanche technicians

An avalanche team now scopes out the 23 avalanche zones, or spots where snow slides commonly occur.

That crew of four or so aboard snowmobiles or cross-country skis work ahead of the plowing equipment to analyze the snowpack. The team observes the snow layout, digs pits and examines layers left by various storms.

The team often skis 10 to 15 miles, hauling explosives and charcoal to blast down potential avalanches before they happen or spread on snow to absorb the sun's heat and help the packed powder melt faster.

The technicians are also responsible for ensuring avalanche zones behind the equipment stay secure.

"Just because it's stable today doesn't mean it's safe tomorrow," said Erin Anders, an avalanche technician. Overnight freezes and daytime melts can quickly change a zone from safe to shaky.

That's why, even with the best efforts by the avalanche technician team, only one vehicle may drive through an avalanche zone at a time. The beginning and exit points are clearly marked, and drivers must radio before entering and once they leave.

Stops are not allowed in the zone for any reason not even to fix a flat tire or a chain.

Avalanche beacons must be worn at all times, as it's easier to find a buried person that way.

Also, anyone traveling the road before it's officially open like those setting up Tuolumne Meadows for the summer must go through avalanche training to learn to identify hazard spots and find buried victims.

Along with improved safety regulations, relations with east-side communities have improved as well.

"I think there's an acceptance that we're probably doing it as well as can be done," Cann said, noting the Park Service now works well with the Mono County Board of Supervisors and others in Mammoth Lakes.

A plaque on a rock near Olmsted Point honors the favorite foreman, but it's covered much of the year by snow.

Still, road crews know where it is and pay their respects as they drive by, said Yosemite Valley Roads Supervisor Ed Appling, who has worked to clear the road since 1973.

Rather than an annual ceremony, Appling said, crews pass by and "just say hi."

Contact Genevieve Bookwalter at gbookwalter@