YELLOWSTONE NATIONAL PARK (AP) - A new type of snowcoach is being tested in Yellowstone National Park - one that is hoped will not have the same problems as previous models.

Fogging windows and broken tracks have plagued snowcoaches used at Flagg Ranch Resort in the John D. Rockefeller, Jr., Memorial Parkway. Those versions were vans converted to snowcoaches by adding four sets of tracks in place of the wheels.

The prototype developed by Heart International, the National Park Service and other private and government officials was developed to get around the previous problems.

Congress has set aside $1.98 million for Yellowstone to buy six of the new snowcoaches, which could be converted to wheels for summer use.

"We were trying to figure out how to make people want to get on this thing," said Dick Rief, vice president of sales and marketing for Heart International. "We found out that riding a bus really needs to be an experience to get people out of their car."

Tim Young, Jackson area representative for the National Parks and Conservation Association, said the snowcoach is able to easily climb the Continental Divide at 35-38 mph.

Rief said there is no need to go faster. "You can't see the park and it bounces you to death," he said.

Young said the vehicle's air suspension and diesel engine - running on biodiesel mix - made for a quiet, comfortable ride.

Sound tests are expected in a couple weeks. "I expect it to be as quiet or quieter than anything we've seen," Rief said.

The snowcoach can carry 18 to 27 passengers, depending on the design, while the wheeled version can carry up to 32 passengers.

Some problems have come up, including window fogging. Rief has added a blower to simulate a top defroster, which keeps the windows clear and will be added to newer versions.