It was just a matter of time before the frustration with metropolitan area traffic took on an international flavor. And who would be the logical first target for a verbal Stinger? The Russians, of course. While Foreign Minister Shevardnadze is scheduled to be in town today to discuss arms, at least one reader is up in arms over the parking habits of his representatives here:Dear Dr. Gridlock:

On successive days I observed D.C. police in the pitiable and wasteful process of ticketing diplomatic cars on 16th Street in front of the Soviet Embassy. As is well known, the only purpose to which the Soviets put these forms is littering. Most days, the Soviets even double park their diplo-bus on 16th Street, closing it down to one lane northbound at the height of rush hour.

The way to fix these flouters of public order is to give them a dose of the free market and lift all parking restrictions within three blocks of the embassy. Three blocks of absolutely open curbs, except, possibly, driveways. All such spaces will, of course, be completely filled with smarmy capitalist exploiters of the proletarian masses by 7 a.m. at the latest, an hour at which no self-respecting plenipotentiary representative of the Worker's Paradise has yet emerged from the sack. MICHAEL B. JENNISON Washington

The Russians say they don't park illegally. "We park in our parking complex," said embassy spokesman Boris Malakhov. Well, there you have it. Apparently you must have mis-observed something, Mr. Jennison.

In the rare instances when one of the Soviets might park illegally, however, you are quite right in concluding that they don't have to worry. "We don't have to pay for parking tickets," Malakhov said. "Under the bilateral agreement between the two countries, we are exempt from paying such tickets."

This comes as something of a surprise to officials at the D.C. Department of Public Works, who initially didn't think diplomats were exempt from parking citations. But, for all practical purposes, they are.

According to the State Department, a parking ticket is worth one point against a diplomat's driving record. If eight points are accumulated, then the driving record is reviewed. But only in an extreme instance would a driver's license be revoked, a spokeswoman said. In fact, that never has happened, she said. Therefore, diplomats don't have to pay parking tickets up to eight points, and don't really have to worry after that either.

The current parking provisions on 16th Street NW near the embassy (located between L and M streets NW) is that two-hour parking is allowed from 9:30 a.m. to 6:30 p.m. on both sides of the street. Diplomatic cars only are allowed in two spaces in front of the embassy. Parking is not alllowed during rush hour.

Informed of Mr. Jennison's complaint, Tara Hamilton, spokeswoman for the D.C. Department of Public Works, promised to investigate. "If, in fact, during rush-hour traffic there are diplomatic cars not abiding by the parking restrictions it may make sense to lift the restrictions as your reader suggests," she said. "Your reader may have a point."

Wonder what effect this would have on arms negotiations . . . . Fired Up Over Smoke-Belchers Dear Gridlock:

I don't understand why trucks and cars aren't prohibited from belching massive clouds of thick, black smoke every time they accelerate. Have you ever driven a few times in rush-hour traffic with buildings lining each side to prevent exchange of air, moving in slow, small gains between stoplights and been behind or beside these lung destroyers?

One time I waited behind two such trucks at a stoplight where a bus stop with a shelter enclosed on three sides with glass was filled with people. The light changed, the first truck accelerated, belching an enormous cloud of thick black smoke which filled the bus stop and obscured the people inside from my view. As I watched in horror, the second truck accelerated and its enormous cloud of black smoke billowed out and into the shelter to add to the first. If I stood beside the street with a coal-burning stove designed to propel large blobs of smoke and let it spew smoke into the rush-hour traffic, would anyone stop me?SARAH BOOHER Alexandria

Given the way police sometimes indifferently attend to traffic laws in the District of Columbia, you could probably fire up that coal-burning stove in the middle of an intersection and not get ticketed.

The answer to your complaint is that there are lots of state and local laws governing air pollution. They vary and, if you'll pardon the expression, are kind of hazy. In Virginia, any vehicle that emits smoke that blocks 20 percent or more of the light getting through for 10 seconds violates state laws on air pollution. In the District, any vehicle that emits smoke of any kind for more than 10 seconds can be cited. You get the picture. The fine is $35 in Virginia, $50 in the District and $20 in Maryland.

But who enforces these regulations? State and local police are supposed to be the primary protectors of our lungs in these cases, but has anyone ever seen a smoke-belcher cited? State air pollution officers say they have to see the violation to write up the ticket.

What can you do? Air pollution officials say you can call them about violators, providing identification such as the driver's license number, or the name and number of the bus or truck company, and an inspector will call the driver or company and ask that the problem be corrected. "We have found that that will do it," said Ray Salehar of the Maryland Vehicle Emission Inspections Office.

So next time you eat smoke, you can note the offender's tags and call the air pollution authority in the jurisdiction where the vehicle has been issued license plates. In the District that is the D.C. Department of Consumer and Regulatory Affairs at 767-7370; in Maryland it is the Vehicle Emissions Inspections Office at 787-2927; in Virginia it is the Regional Air Pollution Control Board at 644-0311.

Metro Responds to Lack of Signs

Remember the lady who wrote in to complain about the lack of signs outside Metro stations posting the hours of the stations? She had arrived at the Huntington station on a Saturday morning for a train to National Airport, but didn't learn the station was closed (after having found three entrances locked) until she actually went down into the station. Metro has decided to do something about that. According to spokeswoman Beverly Silverberg, a directive has gone forth requiring hours to be posted at station entrances on the street level. This is a good thing.

Speaking of Metro, how about Fawn Hall, Ollie North's former secretary, getting a $10 citation for eating a banana in the Metro Center station last week. Although Hall was reportedly indignant, Metro public relations officials are delighted. The publicity, which made national news magazines, is the best possible reminder to the public that eating is not tolerated in Metro stations, according to Metro's spokespeople. Hall purportedly got the ticket after she had been warned by a Metro policeman to stop eating that banana, and polished it off anyway.

On another Metro topic, chief spokeswoman Beverly Silverberg advises customers of Metrorail to pay special attention to the narrow gap between the station platforms and the rail cars. A number of people have had their foot get stuck in that gap. "They are frightened and gesticulate wildly," she said. "Fortunately the train operators know what is happening and there haven't been any serious incidents." But there have been a number of cuts and bruises and sprains. "People need to pay better attention to where they are walking," Silverberg said.

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 problems 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.