Glacier National Park's Going-to-the-Sun Road offers one of the most gorgeous drives in the national park system. Running 50 miles from West Glacier to St. Mary on the east side of the park, the highway cruises past forests thick with larch, hemlock and cedar before climbing to the continent's spine at Logan Pass.

Here, at 6,646 feet, the alpine scenery is stunning: alpine meadows come alive in summer with bursts of wildflowers, shrieking pikas, and wooly mountain goats, while overhead jagged peaks battleship gray climb even higher.

The steep road, which turns 75 this June, also cuts through one of the harsher climates in the Lower 48, and the year-round weather conditions -- heavy snows, torrential rains, frost heaves, runoff, rock falls -- have taken their toll on it. A much-need rehabilitation program got under way in 2004, but now, with not quite 25 percent of the work accomplished, inflation is forcing engineers and park officials to recalculate the project's cost and time-line.

Skyrocketing construction costs are threatening the ambitious rebuild of Glacier National Park's Going-to-the-Sun Road, with latest estimates for the job at least $100 million more than initially thought.

While officials initially pegged the cost of rehabilitating the road at $140 million-$170 million, double-digit inflation in the construction sector has boosted those numbers to somewhere between $240 million and $270 million over the next 8-10 year period, if the project is fully funded.

"Given limited resources and double-digit increases in construction costs, we (the agencies) must determine how best to continue this important project," says Clara Conner, the division engineer for the Federal Highway Administration's Western Federal Lands Highway Division. "As part of our fiduciary responsibility, we must continue to assess and evaluate costs and determine the best course of action."

As things currently stand, the park has obtained $82 million that will fund the rebuild through 2009. Beyond that, though, funding questions take over. In December officials met to discuss the rising costs -- construction costs jumped 19 percent in 2005 and another 20 percent in 2006 -- and try to figure out a solution. Project managers currently are reviewing the latest numbers that have been developed into draft alternatives for revised time-lines, cost-saving measures, and work sequencing. "Decisions regarding any changes will be announced when a course of action is determined," say park officials.

"The project team will continue to monitor and analyze future construction trends in order to provide timely and appropriate management guidance," says Stephanie Dubois, the park's acting superintendent. "The Sun Road is one of our great national treasures, and we will do everything possible to preserve this engineering marvel for the future."