If you have tears to shed and nobody else has prior claim on them, shed them for James E. Clark III. He is acting director of the D.C. Department of Transportation.

Clark's plight is tearful because his job is one that nobody can do well. One cannot hope to master modern traffic; one can only work toward minimizing its frustrations.

Franklin Pierce Adams used to say, "An oboe is an ill woodwind that nobody blows good." Transportation is the oboe of municipal government.

There is never enough money in the budget to do what traffic directors would really like to do. To make matters worse, Washington's circles and diagonal avenues can't be rebuilt. Drivers can't be forced to stop being selfish, inept or careless. It is impossible to assign a sufficient number of policemen to traffic duties, or to make all of them diligent enforcers.

And even when transgressors are brought into court by the ear, smart lawyers get them off with a slap on the wrist. Many a driver whose auto killed somebody has walked out of court upon payment of nominal fine of $100 or less, with no jail time ordered, and not even a temporary suspension of his permission to drive.

In addition, traffic directors are also frustrated by arguments between residents and transients. Inasmuch as all of us live somewhere, and are therefore residents, and all of us move about in areas where other people live, and are therefore transients, one might think that residents and transients understand each other's needs and get along well. Unfortunately, one who thinks this is wrong.

Residents want to keep their own streets quiet and residential in nature. However, they reserve the right to be transients and travel on every other resident's street. The Department of Transportation is frequently called upon to referee these disagreements -- for example, the recent decision to turn 13th Street back to residential status by ending its role as a one-way commuter route during rush hour.

Another aspect of the resident vs. transient struggle manifests itself in those neighborhoods in which residents qualify for special parking privileges but transients do not. When Colleen Fogarty was ticketed in front of her house, she tired to protest that the ticket had been issued without cause. However, she found that the "adjudication" number (727-5000) was busy, busy, busy; and when the phone was finally answered, it was by a recording that told her to hold the line and she would be heard in turn.

She held the line for 1 1/2 hours, she told me. And I told Clark.

He said, "Yes, I know. Many people have complained that they can't get through. We're going to have to do something."

"When?"

"Give me a couple of weeks," he said. "I have more pressing problems right now."

"Like turning 46th Street back into a 'residential' street?"

"Yes," he said frankly. "That's one of them. But if you write about it, please don't say we're installing speed bumps, because that would create the impression that we're going to put in those severe bumps one sometimes finds in shopping malls. Ours will be humps rather than bumps -- about 12 feet of pavement that's raised a maximum of four inches -- just enough to remind a driver that he's on a 25-mile-an-hour residential street."

The work will begin "any day now." Nine humps will be built into the one-mile stretch of roadway that runs between Massachusets Avenue and River Road. There will also be lots of signs and flashing lights warning that the speed limit is 25 miles an hour for autos and 15 miles an hour for all other vehicles, even motorcycles.

Clark says 99 percent of the street's residents are "in concurrence" with his plans. He will follow developments on 46th Street with special interest because the humps-not-bumps are obviously meant to be a test of Clark's ideas about urban traffic control.

He says, "I am well aware that the automobile can't be banned from modern cities, and that there will always be people who are not adequately served by public transportation. I realize, too, that even when people do live a few steps from a bus or subway stop, it is not easy to persuade some of them to change habits of long standing. But we must make the effort. We must try to woo as many people as possible away from their private autos. A modern city can accommodate only a finite number of private vehicles."