National Airport is bad enough already, what with the traffic congestion, insufficient parking, crowded terminals, the cancelled and delayed flights. Now, on top of that, motorists must brace themselves for possible dental work if they try to take the torn up Airport Connector road to get there.

Workers took the surface off this vital airport entrance some time ago, and it seems as though it's taking forever to fix it. The connector is one of the major entrances to the airport. It carries traffic from Jefferson Davis Highway (Rte. 1) in Arlington over the Alexandria rail yards to the airport entrance (see map below).

Motorists now must slow almost to a standstill to avoid losing dentures and car parts on steel plates covering holes in the road. Hubcaps and exhaust equipment litter the side of the road, testimony to the harm that road can inflict on anyone not making a sudden and dramatic reduction in speed.

"We are very much aware that it is not a pleasant place to drive," said Virginia highway spokeswoman Marianne Pastor.

What happened is that contractors working for the highway department stripped off the asphalt of the road on May 15 to make repairs on the deck and joints of the overpass structure. Once the asphalt was removed, Pastor said, the contractors found "a whole lot more work than we thought."

There were further problems. Arlington County has a noise ordinance that prohibits work at night. The Federal Aviation Administration insisted that no work be done during morning and evening rush hours to allow traffic into and out of the airport during peak use hours. So the highway department agreed to limit construction work to between 9 a.m. and 3 p.m. "Then things became further complicated because under that bridge is a parking area, and we have to be sure as we are patching the concrete we are not knocking concrete down on cars," Pastor said.

The upshot is that what was expected to be an eight-week project now is not scheduled for completion until Oct. 1, at the earliest.

Pastor said that under the circumstances, nothing could have been done differently. Following this inquiry, she said, the highway department, the FAA and the contractor are trying to find room to allow more hours for construction.

Folks, 1.4 million people use National Airport each month. To tie up a major entrance into that airport for 4 1/2 months seems wrong. There must have been a better way, like working out a longer construction schedule than six hours a day. And maybe prohibiting cars from parking under the overpass so work could proceed at a faster pace. This situation underscores the need for highway departments to develop one more layer of sensitivity to the needs of motorists and look for ways to expedite work projects on vital roads. Someone has got to give greater consideration to drivers. Bike Couriers (Con't.) Dear Dr. Gridlock:

Prompted by the letter{s} you received from {the} Rev. Kenneth A. Bastin about his encounters with bicycle couriers and your response that help may be on the way, I write in the fervent hope that you are right. I was nearly run into the other day by a bicycle courier as he came through a red light as I was crossing K Street, and I, too, was struck in the face as the result as a consequence of the resulting exchange. The proposed bill {before the D.C. Council} sounds like a good idea, but the required identification had better be highly visible. The legislation is badly overdue. ELLIOT L. RICHARDSON Washington

The writer is the former attorney general, secretary of defense and secretary of health, education and welfare in the Nixon administration.

The legislation referred to is the Commercial Bicylists Licensing Act, introduced to the D.C. Council this summer by council member Nadine P. Winter (D-Ward 6). Her bill would require commercial bicyclists to be licensed, wear identification, and receive training from their companies. The bill comes up for consideration when the council returns from summer recess on Sept. 29. A public hearing is scheduled for 10 a.m. Oct. 21 in Room 500 of the District Building. Some readers don't see a need for any such legislation. Read on.Dear Dr. Gridlock:

I'm not sure I understand what {the} Rev. Bastin's accounts of his encounters with the bike messenger have to do with me. Bastin has filed a complaint with the police and if they locate the loose id who is tormenting him, they will charge the messenger with spitting and hitting and not, I suppose, with improper passing.

This isn't a traffic problem at all, and unless we're talking about profiles of deviant behavior, a controversial subject, it's not likely an issue that will be addressed in council member Winter's Commercial Bicyclists Licensing Act.

Addressing that act, I'm against it for reasons you might emphathize with more easily if Winter were to introduce acts licensing your work or requiring you to wear a number on your back.

I can think of reasons why in the public interest it might be necessary to license clergymen and journalists, and, you will admit, there have been complaints.

I won't press for it, though, and am pleased to read that the act to license bicycle messengers will be considered in late September when the weather should be more temperate. HENRY A. TENAGLIO JR. Washington Dear Dr. Gridlock:

I wish to correct your denouncement of July 3, where you stated that bicyclists "are often the most blatant lawbreakers you see on city streets." Not so; it is the jaywalking pedestrian. Remember a few years back when police handed out jaywalking tickets? Why did they stop this crackdown?

Police Chief {Maurice T.} Turner is following the policy of other cities in this gray area of the law, i.e. victimless crime. Whether it's the cyclist's 30-pound Schwinn or the pedestrian's two-pound shoes, this weaponry in no way compares to that of a motorist's two-ton Buick. When this amount of destructive mass violates the law, it can maim and kill. But I have yet to witness or hear of a motorist being ticketed for right-turn-on-red infractions, while I have seen police occasionally ticket bicycle messengers. Perhaps many irate motorists would like to see "occasionally" changed to "frequently." For the sake of society, I hope the police continue to give this issue a large degree of benign neglect, and crack down forceably on the real threats to public safety. EDWARD ABRAMIC Washington

While being hit with a 30-pound Schwinn may not compare with being hit by a two-ton Buick, as you say, bicylists can cause accidents when they run red lights, drive on the wrong side of the street, weave in and out of traffic and treat pedestrians like markers on a ski course. Each time we bring up this subject we get a number of impassioned letters from probikers and antibikers. With both groups having a right to the roads, and with all of us trying to cope with congestion, we can agree on this: Some motorists and some bicylists drive irresponsibly. Police ought to crack down on both groups.

Regarding Winter's bill, it's hard to see how the training of commercial bicyclists would be detrimental to the public interest. And since bicyclists are entitled to use the same roads and are required to obey the same traffic laws as motorists, and because they often can go faster on downtown streets than motorists can, shouldn't they also be licensed and display identification, like the motorists they share the roads with? Please proceed, Ms. Winter.

Hidden Entrance Ramps Dear Dr. Gridlock:

When I am in downtown Washington, I often want to get on I-395 to begin my trip home to Bethesda. I would like to know where the entrance ramps are being hidden. I occasionally spot signs for 395, but after I start to follow the signs, I have gotten lost. A driver needs more cueing than has been provided. NEIL Z. BEIN Bethesda

Tara Hamilton, spokeswoman for the D.C. Department of Public Works, says her department is aware that "some of our I-395 signs are missing and that a few more would be helpful." Therefore, she said, the department plans to install about 75 more signs, to I-395, Rte. 50 and Rte. 1, to guide people to those main roads. This should be done by the end of the year.

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.