Glacier National Park engineers have sized up "The Big Drift," the last obstacle to clearing Going-to-the-Sun for traffic, and it appears as big as ever.

This year the drift is estimated to cover 45 feet at its deepest point, and its western edge is crowned with a large and unstable cornice. The drift forms every year in the same place as a result of topography and wind.

Excavators, bulldozers, plows and even explosives will probably be used to tackle the drift, park officials said. Explosives may be needed to knock down the cornice, clearing the way for heavy equipment to start shaving away the drift itself.

As of Tuesday, plow crews were approaching the drift from both sides - the west-side crew is in the Oberlin Bend area and is typically responsible for the initial or "pioneering" swaths across the drift. Once conditions are considered safe enough, equipment will approach the drift from the east.

Park officials stress that the plowing schedules and the eventual road opening at Logan Pass hinge on many factors, including weather, visibility, avalanche hazards, new snow or ice, rock fall and equipment failures.

"Our snow removal crews made speedy progress earlier this spring but up to now, winter weather has kept a hold on the snow in the mountains above the Going-to-the-Sun Road," Glacier Superintendent Mick Holm said. "The hazard of avalanches may increase dramatically until the snowpack undergoes a sustained period of melting or direct sun for a period of days. The snow load in the mountains above Sun Road must slide or stabilize before we can complete the annual clearing and subsequent opening of the road over Logan Pass."

Preparing the road for traffic involves clearing rocks and other debris, installation of guardrails and signs, and clearing snow from the Logan Pass Visitor Center parking lot and walkways.

The earliest opening on record for Sun Road at Logan Pass was May 16, 1987.

Sun Road is currently open to vehicles as far as the Avalanche area on the west side and Jackson Glacier Overlook on the east side.

Hikers and bicyclists can go beyond those points, as far as Triple Arches on the west side and No Stump on the east side of the park.

Reporter Jim Mann may be reached at 758-4407 or by e-mail at jmann@dailyinterlake.com