Reporting from Yosemite National Park -- It’s nearly summer, and swarms of cars, buses and RVs breeze through Yosemite Valley as if on conveyor belts of asphalt. But up here at 8,400 feet, along the snowbound solitude of Tioga Road, winter is still in control.

Three members of a National Park Service avalanche control team move out from their camp near Olmsted Point. They are here to bend nature’s timetable and help clear the highest automobile route across the Sierra.

From a distance, they are ephemeral figures dwarfed by the eternal landscape — a steep, treeless mountainside loaded with tons of ice and snow just waiting for a trigger.

Interactive: Four seasons in Yosemite


It is shortly after 5 a.m. The temperature is in the mid-20s, and a blue dawn signals the sun’s arrival. Time is short.

Tim Esquivel and Steve Lynds stop to load their backpacks from a sled laden with supplies — explosives, a spool of detonator cord, bags of charcoal, shovels. Both are in their mid-40s with ponytails and earrings, both strong as climbing rope.

Edward Canapary, 44, has climbed above them and is whaling on the frozen snow with a pick-ax. Ching-ka! Ching-ka! Chunks skitter down the hill and into the valley below.

He works fast. Spring in the mountains is a violent alchemy of hydraulics and gravity. Snowfields benignantly frozen at night awaken to the sun’s heat. This windless morning’s silence will soon be replaced by the ominous gurgle of percolating water lubricating the rock underneath.


Ching-ka! Ching-ka! The minutes tick by. The sky brightens imperceptibly.

When the holes are dug, Canapary calls to the men below on his radio.

“Bring the bombs up.”

From the nearest patch of dry road, it’s more than an hour by snowmobile to Olmsted Point, a sublime stage from which to view the grandeur of Yosemite National Park. It’s also the most unpredictable and dangerous avalanche zone on Tioga Road, which bisects the park from east to west.


Each fall the road closes for the winter. Each spring the National Park Service, Caltrans and Mono County launch a monumental effort to clear it, more than 50 miles blocked by towering snowdrifts, uprooted trees and fallen rock.

Letting it melt at its own pace isn’t considered an option.

Tioga Road — also known as California Highway 120 — is critical to the small-town tourism economies on both sides of the Sierra. Opening it as soon as possible is important to park managers, too. Most of Yosemite’s 4 million annual visitors come between Memorial Day and Labor Day; without access to facilities and trails along Tioga Road, the tourist hub in Yosemite Valley would resemble the 405 during a SigAlert.

The contours of today’s Tioga Road and its promise of a path through the Sierra’s inhospitable maze has attracted travelers for millenniums.


Native Americans hunted along well-worn game tracks. John Muir herded sheep through the area in 1869. Chinese laborers came next, building a wagon road to service mines that didn’t pan out. Then came stockmen and, eventually, tourists in horse-drawn wagons.

Finally, Stephen Mather, industrialist, conservationist and the first head of the National Park Service, arranged for the right-of-way’s purchase, repaired the road and had it donated to the government. In so doing, he gave the road its modern mission — and changed Yosemite forever. A dirt throughway opened in July 1915 and 190 cars crossed over that year. Five years later, more than 1,000 cars a week did.

Early on, Tioga Road’s opening and the steadily growing traffic counts garnered bold headlines in The Times. The newspaper teamed with automakers to sponsor “scout cars,” whose drivers reported on early season conditions.

“In conquering the Tioga Pass,” read a dispatch from 1922, “the Buick crew … negotiated forty-nine snowdrifts, and sawed their way through twenty-one trees which blocked the road. Once the Buick lost its moorings on an artificial roadbed and sank in to the masts, it required three days to bring the ship to the surface.”


Tioga Road and its later paving and modernization would come to embody one of the competing pressures on Yosemite: the desire for convenient visitor access. Last year, 211,993 vehicles plied the route.

Plowing typically begins in mid-April with an eye toward opening the road before Memorial Day. This year, the work has been particularly daunting, and the route isn’t expected to be fully open for at least another week.

A wild winter left Yosemite with nearly twice its average snowpack — as much as 18 feet along Tioga Road, the most since 1995. Spring blizzards knocked out power to the park and surrounding towns and delayed the start of plowing. By the second week of May, much of Tioga Road inside the park remained entombed in wet, compacted snow.

“It’s like plowing cement,” said bulldozer operator Ed Appling, who was still miles — and weeks — away from where the avalanche team was working to tame Olmsted Point in early May.


Appling, 58, has spent a lifetime on Tioga Road. As a child, he watched his father drill holes in rock walls for dynamite during the route’s late-1950s reconstruction. For the last 34 years he has plowed it — earning Appling the nickname “King of the Road.”

“It takes a lot of spring openings to get to the point where you know what you’re doing,” Appling said.

“Instead of taking big bites out of the snow, it’s better to take a bunch of small bites. Instead of go-

ing as fast as you can, it’s better to go slower and let the machine eat it on its own.”


Bulldozers rolling and pitching like ships on rough seas take the first passes at Tioga Road’s drifts, knocking them down by half.

Massive rotors, the Tyrannosaurus rex of snowblowers, follow. With 5-foot wheels corseted in doughnut-sized chain link and a maw of steel blades, the 53,000-pound machines gobble and spew out 500 tons of snow per hour in long arcs.

Mile by mile, the machines carve a two-lane chute through forests, around tight curves and across white-knuckle precipices where the road’s path isn’t obvious and a wrong move could mean falling into the abyss.

The dangers come from above as well. Canapary, Lynds and Esquivel make up one of two teams that monitor Tioga Road’s 26 avalanche zones — slopes pitched between 30 degrees and 45 degrees, which collect snow through the winter much as a coiled spring stores energy.


They camp in the backcountry for days at a time. They dig pits in slide paths to study the multiple layers of frozen and loose snow the way geologists would pore over the strata of a canyon wall.

The stability of these slopes changes daily, even hourly. Rapid warming, rain and new or blowing snow add weight, causing slabs to fracture and roar down at speeds approaching 80 mph.

“Predicting an avalanche is like predicting an earthquake,” Lynds said.

They nudge the process along with explosives — sticks of duct-taped charges and a mixture of ammonium nitrate and fuel oil poured into plastic bags with an old coffee can.


Cantilevered cornices are blasted from ridges. Bombs buried along with charcoal send up plumes of fine silt across slide paths; the blackened snow absorbs heat and melts quicker. When a slope is too unstable to climb, the crew rappels from cliff tops and tosses the bombs.

All three men have spent much of their working lives outdoors — repairing trails, building bridges and operating heavy equipment. (Canapary and his wife honeymooned in a snow cave.)

Their work is exacting and exhausting — and the consequence of a deadly 1995 avalanche.

It was mid-June and the bulldozers had reached Olmsted Point with a couple of weeks’ work still to go. Barry Hance, 43, was a veteran road crew supervisor who knew the hazards. Hance decided to keep things moving by clearing the most treacherous 300 yards of Tioga Road himself.


“He wasn’t even supposed to be working that day,” Lynds said. “But he was the boss. He was the most skilled.”

In an instant, a torrent of snow raced down the slope, swallowed Hance’s bulldozer and killed him.

An expert in avalanche control was hired to study Tioga Road’s slide paths and overhaul the park’s attack plan. Teams were formed and trained in snow science — how to size up risks and avoid catastrophes.

All workers are now required to take an annual avalanche survival course. They learn to search for victims with electronic beacons and metal probes. They practice shoveling and extraction techniques. They learn that nine of 10 avalanche victims live if reached within 15 minutes — and that survival rates fall off a cliff after that.


“If you get caught in a slide, try to swim on the surface to keep from being buried,” Esquivel told a class of 15 park employees, most of them beefy guys with beards and bear-paw hands. “Yell loudly so other people can see where you are. Then close your mouth.”

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Esquivel and Lynds dig their crampons into the slope and make their way up to Canapary with the dexterity of mountain goats, despite their heavy loads.

They work fast, loading the holes with explosives and charcoal and connecting the charges to one another. A strip of sunlight appears on the top of the cliff and inches down toward them.


Soon the snow sparkles as if strewn with diamonds, and the soft gurgling of percolating water begins.

Canapary spools out cord to a spot a couple hundred yards away and attaches it to an igniter.

“If anything comes flying at us, dive in there,” he said, pointing to a spot behind a boulder and a juniper tree.

“Clear the area! Blasting!” he yells down the valley, just in case there are backcountry skiers nearby.


“FIRE IN THE HOLE!”

With the push of a button the silence is shattered. The slope underfoot trembles as if rocked by an earthquake. Fire and charcoal fill the sky. And waves of concussion roll through the mountains toward Yosemite Valley, winter’s echo heralding summer’s approach.

Interactive: Four seasons in Yosemite

mike.anton@latimes.com