Robert Arnberger, superintendent of the park that celebrates one of the geologic wonders of the world--"this incredible hole," he calls it--can only shake his head at the irony of what has happened to the Grand Canyon under the weight of nearly 5 million visitors a year.

"What we've done here, by accident and premeditation, we've taken this special place that is different from everything in your life and we've homogenized it so it's just like your life," Arnberger said. "It's full of cars, you're constantly looking for parking places, you're standing around in lines."

As Arnberger spoke in his office at park headquarters one recent day, some of the 20,000 people who visit the park every day during peak season sat in their cars in the parking lot outside, their motors idling, waiting to pounce when a spot opened to allow them access to the park's cramped visitor center.

Up and down the scenic drive that meanders along the south rim of the canyon, hundreds of other cars were parked haphazardly along the roadside because the canyon overlooks were full. A few miles to the south in the gateway village of Tusayan--a hodgepodge of motels, trading posts and fast-food restaurants--planes and helicopters carting air tourists roared off the small airstrip in a steady stream.

The average Grand Canyon National Park tourist now spends only a small portion of his or her visit actually taking in the scenic wonders of this place or learning more about it, said Arizona developer Tom De Paolo. The rest of the time, he said, "you're competing for parking, you're competing for something to eat, you're buying a rubber tomahawk from Taiwan, and that's it."

Arnberger and De Paolo hope to change that through-the-windshield experience, and perhaps provide a model for the entire park system, where, despite a few evolving attempts at mass transit in places such as Zion and Acadia national parks, the automobile is still king.

In April, Grand Canyon National Park broke ground on a new transportation hub and visitor orientation facility near Mather Point on the south rim that is the linchpin of a radical plan to change the way tourists visit the canyon, a plan that will in large measure banish private automobiles in favor of light rail, alternate-fuel buses, bicycles and human feet.

Under a new plan adopted in 1995 and now being implemented, Grand Canyon Village also will be transformed, with two tired, ugly motels ripped out and a "heritage education campus" created. Visitors will be offered a much richer experience, with opportunities to learn in depth about the canyon's geology, environment and Native American cultural history through innovative partnerships with private industry and educational institutions.

In another important step, the Forest Service last month approved De Paolo's proposal for a land swap and $330 million development outside the park near Tusayan. The project is designed to ease crowding in the park with 1,200 units of new lodging, park employee housing and community facilities such as a school, medical clinic and fire and police stations.

Hailed by environmental groups and Indian tribes who helped plan it, the development will incorporate advanced environmental design and energy-saving measures. It should prevent further depletion of springs and seeps in the canyon by relying on water brought in by pipeline and rail rather than underground wells. In addition, designers say it will mesh with the park's new light-rail system and offer tribes a piece of the economic pie and a role in telling the cultural story of the canyon.

"We saw a tremendous opportunity to create a new model and to solve some park problems," said Dave Simon, the southwest representative for the National Parks and Conservation Association, in explaining how environmentalists came to cooperate with the developer of Canyon Forest Village, as the project is called. "We could not afford to do nothing. The choice was not between whether or not development was going to continue to occur. The choice was between continuing historic patterns of poor, unplanned development or choosing to master-plan."

Another change, one that environmental groups say does not go far enough, also is in the works. The Federal Aviation Administration proposed new rules last month governing air tours. The rules, designed to meet congressionally mandated requirements for the "substantial restoration of natural quiet," would cap the number of canyon overflights at the 1997-98 level of 88,000.

Even taken together, these changes will never meet the challenge President Theodore Roosevelt laid down in 1903, five years before he extended federal protections to the canyon by declaring it a national monument. "Leave it as it is," Roosevelt said then. "You cannot improve on it. The ages have been at work on it, and man can only mar it."

Man has marred it over the years because the canyon is a huge cash cow, generating as much as $1 billion a year in tourism, and because the post-World War II development of an automobile culture has made it accessible. Business people in Tusayan and other communities that funnel visitors to the canyon worry that Canyon Forest Village will put them at a disadvantage, and they are threatening legal action to block the Forest Service decision and a political campaign against the zoning changes that will be required before construction can begin.

Chris Thurston, owner of the Red Feather Lodge in Tusayan, argues that Canyon Forest Village will benefit from a huge government subsidy because of the land exchange with the Forest Service and will have an unfair competitive advantage over other area motels. He also is skeptical of whether most tourists will accept the changes underway at the canyon.

"Ultimately, if it makes things more inconvenient for the visitor, it will be a detriment," he said. "I don't need someone to tell me how to interpret the canyon. If I want to see it through the window of my car as I'm driving through, that should be up to me."

Air tour operators, who take about 800,000 passengers a year on scenic flights over the canyon, also are mobilizing to defeat the new FAA rules. The base year used by the FAA in setting the number of flights, said Barry Baker of Grand Canyon Airlines, was an abnormally slow year because of the Asian financial crisis and will result in actual flight cutbacks for many operators. Independent studies, Baker argued, have shown that the government's goal of restoring natural quiet to half of the park for more than 75 percent of the day already has been achieved.

Sitting in his office, where a letter on his desk threatens legal action by the town of Williams, Ariz., if he doesn't stop referring to Canyon Forest Village as a "gateway" community, Arnberger ponders aloud how national parks became more important for their commercial possibilities than for preserving natural resources.

"There's always been an element of profit in the idea of parks," he said. "The early fathers of the park system saw that as an important part, but there was a better balance." Now, he said, "the constant argument over the almighty dollar seems to typify everything."

Perhaps, Arnberger believes, the Grand Canyon with its makeover can start to reverse that trend. In just a few years, visitors here will be able to leave their cars behind and walk or bike on greenways along the rim, savoring the hush that contributes so much to the canyon's magnificence.

In Grand Canyon village, they may be able to view an exhibit of how artists portray the canyon, or join a Park Service team working to eradicate non-native species, or listen to Hopi elders explain the canyon's special place in their history.

"This hole deserves our best shot," said Arnberger. "Mediocrity is not acceptable."

CAPTION: A motorist cruises the Tusayan strip, a crowded row of motels and restaurants near the Grand Canyon. A $330 million development is planned nearby.