John F. Herrity, chairman of the Fairfax County Board of Supervisors, discovered a D.C. Transportation Department "boot" -- the scourge of parking ticket scofflaws -- clamped to the left front wheel of his green Toyota in downtown Washington yesterday.

Less than an hour later and after a telephone call by Herrity to city hall, the boot was removed, and Herrity drove back to suburban Virginia.

It wasn't "any big deal," Herrity said afterward. He and transportation department officials explained it this way:

Herrity had driven into Washington on personal business and parked in the 1700 block of M Street NW.

A transportation department crew spotted the Toyota and matched it to a computer printout showing it had accumulated four unpaid tickets since 1976, totaling $90 in fines and late penalties.

The crew promptly affixed a large metal boot to the car, immobilizing it. Ordinally, the owner of a booted vehicle cannot get it released until he has paid all back tickets and penalties, a process that can take 24 hours or more.

When Herrity discovered the boot on his Toyota at about 3 p.m. yesterday, he said he "tried vigorously" for 15 to 20 minutes to call the transportation department number listed on the booting ticket, "but it was constantly busy."

So he called the office of D.C. City Administrator Elijah B. Rogers at the District Building, identified himself and explained his problem to a Rogers assistant. The assistant called John M. Brophy, head of parking enforcement in the transportation department, who in turn called Herrity, who was waiting at a phone booth near his immobilized car.

Herrity told Brophy he did not believe he had accumulated any tickets, but if he had, he pledged to pay them promptly. In the meantime, he wanted to go home.

Brophy said he told Herrity the department's computer had "made errors" in the past, and other citizens complaining like Herrity had been correct in their assertions of innocence.

Brophy said he thus agreed to let Herrity go for the moment and ordered the boot removed. He said he would check the validity of the four alleged tickets today and call Herrity for payment on any if necessary.

"I never met Mr. Herrity," Brophy said, "but I think he is an honorable man . . . It's unconscionable to think he would try to get away with four parking tickets."

Herrity said later in a telephone interview he did not think he had ever received a D.C. parking ticket, "but I have four teen-age drivers in my family," and it is possible one or more of them accumulated the tickets.

"I don't see any big deal in this," he said. "I was not trying to get away with anything . . . I would have cleared it through normal channels if I could have, but the (transportation department phone) line was constantly busy."