What can you do if you see someone deliberately run a red light? Or block an intersection? Or otherwise violate traffic laws? Is there anything we can do, or are we all potted plants when another person commits a driving sin and there is no policeman around? A number of motorists have asked this, most recently on a WAMU-FM call in-show.

The answer, given the anger and frustration on the roads these days, may lead to a new dimension in traffic enforcement. If so, here's looking at you:

In Maryland, police say they will follow up a phone call if the witness has the tag number, location and time of incident, can positively identify the driver and is willing to testify in court.

In Virginia, police won't press charges if they don't see the violation. Motorists, however, can file a complaint with a local magistrate. If the magistrate determines there is probable cause, he or she can issue a summons and the matter can go to court. The witness must be able to make an identification and be willing to testify.

In the District of Columbia, police have to see the violation to issue a citation for routine traffic violations.

There are exceptions to these guidelines. If a driver sees a violation on the order of a hit-and-run, reckless driving or drunk driving, police are asking for an immediate call through 911 so they can check into it.

Also, police say they still want to hear about routine traffic violations, even if the motorist does not have a positive identification, or is not willing to testify, and even if the matter is not something the police will pursue on an individual basis. Police say they are looking for trends, such as people routinely running a particular red light. If enough such calls are received, police said they will monitor the location.

Most people will not be able to make a positive identification of a stranger on the move. The need to testify is going to deter others. But there may be an option here for a persistent person who just can't take it any more.

Here are the numbers to call:

Maryland: Montgomery County police, 279-8000; Prince George's police, 350-9700; Howard County police, 992-2266; Anne Arundel County police 987-4050, Anne Arundel District Court commissioner 974-2616; Charles County sheriff, 934-2222, Charles District Court commissioner, 934-3081; Calvert County sheriff, 535-1400; St. Mary's police, 475-8008; Frederick police, 694-2071. In Anne Arundel and Charles counties, call police for routine complaints. Also, in those two counties, the district commissioner may issue a summons based on an individual complaint.

Virginia: Fairfax County police, 691-2131, Fairfax magistrate; 273-1155, Alexandria police, 750-6411, Alexandria magistrate, 838-4515; Arlington police, 558-2459, Arlington magistrate, 558-2304 (the Arlington magistrate wants police called first); Prince William County police, 335-6500, Prince William magistrate, 631-1703; Loudoun sheriff, 777-0445, Loudoun magistrate 777-0383.

District of Columbia, 727-4326.

Comments, about this item in particular, are welcome. No Boating, No Parking Dear Dr. Gridlock:

On Aug. 12, 1987, at 12:17 p.m. I received a parking ticket at the Thompson Boat Center in Washington, D.C. I am paying the $20 fine, although I know I am not guilty. I realize there is nothing I can do about this ticket, but this letter may serve to save some other unfortunate person from receiving a ticket as I did.

There is no sign on entering the parking lot that indicates that the lot is restricted to boat patrons only. The sign that does exist states: Thompson Boat Center U.S. Department of the Interior National Park Service

Once inside the lot, my two passengers and I looked (obviously in vain) to find a sign that would indicate that we couldn't park in the facility. We did this by driving through the entire lot once. We could find no such sign. There were signs, however, that indicated a two-hour parking limit, of which we used one hour and 57 minutes.

Needless to say, I was shocked to find a ticket affixed to my windshield upon our returning to my car. At that point we once again drove through the parking lot to see if we could find any sign indicating that we could not park in the lot. On our third drive through the lot, we finally spotted a signpost. This one sign was obscured by the branch and leaves of a tree. We had to get out of the car and walk under the tree to read the sign.

So I must admit that there is a sign, albeit obscurely hidden from view that says: "2 Hour Parking for Boat Patrons Only"

However, I must also say that unless the sign is easily visible, I don't deserve a ticket. Also, this is the first time that I have ever been told I can't park in a national park parking lot. This is the real crime committed here, that a national park parking lot is restricted to parking by boat patrons only! My tax dollars pay for these parks, too! LORETTA SCHULZ Oakton

Earl Kittleman, spokesman for the National Park Service, said it is possible there was only one sign at that lot when you were ticketed because "people keep uprooting the signs and taking them away." As of this week, he said, there are eight signs at that lot.

As to the use of the lot, Kittleman said: "It's a parking facility that has space for 50 vehicles and is for the use of the patrons of the boat house. If we opened it up {to everybody} it's so close to the city the 50 spaces would be gone and the boat patrons wouldn't have a chance. The commuter would come in at 6 a.m. and take all the spaces.

"The Park Service is mandated to provide recreational services in park areas for the use of parks and it's entirely within those parameters that we operate there. We have a concessionaire running a boat facility and the parking spaces are for that."

Cooler Times Are Coming Dear Dr. Gridlock:

The heat and humidity in the Smithsonian Metro station is always uncomfortable. It is always humid, and sometimes it is brutally hot, too. Even short waits for trains this summer were often unbearable. The problem exists whether the station is crowded or not, so it's probably either a matter of adjusting the air conditioning equipment or correcting a design problem.

I have called the Metro consumer compaint line about the problem at least three times, but nothing has been done. We commuters deserve better. Can you help?ROBERT G. BIDWELL, JR. Reston

You're right. The Smithsonian station is the only one in the Metro system that has no air conditioning. The reason, according to Metro, is that the temporary "chiller plant" at 12th and G streets NW that generates air conditioning for Metro Center and Federal Triangle stations can't reach Smithsonian. A long-term squabble over land use blocked Metro's plans to fix the problem. Now, according to spokeswoman Beverly Silverberg, a new chiller plant, capable of supplying cold air to all three of the downtown stations, is planned for the basement of a new hotel near Metro Center. The new chiller plant should be completed by next year, and air conditioning will be provided to the Smithsonian station by the summer of 1989, Silverberg said.

Inspection Note

Here's a note of importance for District residents who are going to get their cars inspected in the next few months. The D.C. Department of Public Works is going to close down the Northeast inspection station for renovation beginning next Monday through February. That means everyone will have to use the other inspection station at 1001 Half St. SW. The hours at that station will be extended starting Oct. 5. The new hours will be 7 a.m. to 10 p.m. Monday through Friday and 7 a.m. to 3 p.m. on Saturday. The Northeast station, at 1827 West Virginia Ave. NE, is almost 50 years old and needs repairs, particularly to the ventilation system, as long-suffering customers can attest. D.C. officials plan to note how many residents use the other station in the evening or on Saturday, and may adjust hours at the stations when the Northeast work is done.

A Quiet Discussion of Hood Latches Dear Dr. Gridlock:

Sorry Doc, but you blew it. The letter from Paul Pasquarella {Sept. 25} had to be a phony.

I cannot imagine anyone being able to drive and not even knowing where the hood latch is located and you only thanking him for the letter.

I wonder what he does in rain or snow.

Now I can understand why there are people in the passing lane doing only 50 mph and then {making an obscene gesture} when you blink your lights and try to get them to move over so you can go at least the speed limit. It is probably Paul hunting for a gas station on the median strip.

For shame, Doc. LLOYD BEASLEY Dunkirk, Md.

Now, now, Mr. Beasley, aren't you being a tad harsh? There are many, many people who don't know where the hood latch is because they've never used it. These folks never, ever, check their oil or water or otherwise look under the hood (that's left to gas station attendents) and therefore they don't know where the hood latch is.

Now, about your habit of blinking lights at motorists. That's illegal. It's a potentially dangerous distraction. The motorist who irks you has a right to drive in the left lane at that speed. You should signal and pass cautiously on the right when it is safe to do so.

Thanks for your letter.

Dr. Gridlock appears in this section each Friday to explore what makes it difficult to get around on roads, from misleading signs to parking problems to chronic bottlenecks. We'll try to find out why bad situations exist and what is being done about them. You can suggest topics by writing to GRIDLOCK, c/o The Washington Post, 1150 15th St. NW, Washington, D.C. 20071. Please include your full name, address and day and evening phone numbers.