There was no audience on the bus, except for five understanding colleagues, but still Mike Adams was "nervous as heck."

The driver, William Sartor, made the right turn onto Ohio Drive SW and then, perhaps thrown off by the barricades, the three auxiliary officers or the cameraman capturing the moment, he asked:

"Now what do we do?"

So went the maiden voyage of the National Park Service's "cruise line," launched on a day when sea gulls outnumbered people at East Potomac Park and the weather was, perhaps fittingly, watery.

It is the Park Service's answer to the "cruising gridlock" caused by circling cars at the park, also known as Hains Point. Starting yesterday, the shuttle will run every half-hour between 3 and 10:30 p.m. Saturdays, Sundays and holidays. The one-way portion of Ohio Drive will remain closed to traffic until 6 a.m. the following day. The change will not affect those who use the golf and tennis facilities, or the section of Ohio Drive that circles West Potomac Park.

The free shuttle service has caused uneasiness among some park regulars who see it as an intrusion.

The Park Service, however, points out that the gridlock was so awful at times that Ohio Drive had to be closed arbitrarily on weekends. That meant other park patrons were kept out until traffic cleared, something that won't occur with the shuttle.

But that's not all. And here's where Mike Adams comes in.

He and Candace Cowley, a park ranger just in from Idaho, will conduct tours from the bus, pointing out the park's sights. People will be able to get on and off at any of six stops along the 3.2-mile trip.

The maiden voyage for the shuttle was also the debut for Adams, a New Yorker who hit stride just seconds after he said he was nervous. Addressing the crowd -- Sartor, Cowley, Donna Donaldson, Thaddeus McKoy and Howard Wilder, all with the Park Service -- Adams was fast with facts.

A round of golf cost 25 cents in 1917 or 1918, when the first nine holes on the park's course were built; and that's where Washington's first ferry was moored, until 1923, when Congress didn't come through with the money.

"Here is our first stop, and we hope you enjoy your stay in the park," he announces when the bus pulls into Parking Lot 6.

No one gets off. No one gets on.

And so it went, past The Awakening ("My, what a beautiful statue") and the Mexican playground ("donated by Mexico"). Sartor, the driver, was so absorbed that he completely forgot to stop. "That was Parking Lot 21," Adams said.

The round trip was only 16 minutes long, far shorter than it will be when people with picnic baskets are getting on and off. Donaldson, the park ranger, said the test will come with the crowds.

And Adams? "You may want to know how Hains Point became Hains Point. Well . . . . "