Seen from the air at the height of a morning rush hour, as 175,000 cars and buses from the suburbs attempt to reach points downtown and near the Pentagon, the Washington area's traffic snarls have an almost pleasing sense of order.

Day after day, vehicles from neat, slowly advancing queues at the same spots on major arteries such as Shirley Highway and New York Avenue. Jams materialize promptly at predictable times, normally linked to federal office hours, then dissipate on schedule.

On the ground, drivers sweating out tangles like the daily backup on the Southwest Freeway -- 102,000 vehicles use it on a typical weekday -- gain an entirely different impression: complete chaos.

For them, it is small consolation that in past decades billions of dollars have been devoted to expressways and the subway system. Wheel-pounding delays on car trips to work remain a fact of urban life -- and traffic experts all say that's not likely to change soon, if ever.

Traffic jams build up daily at the same spots for simple reasons that generations of traffic engineers have battled unsuccessfully: funding shortages, poor planning, driver psychology, disputes between local governments and, most importantly, a basic law of physical science -- two bodies cannot occupy the same space at the same time.

In some cases, jams are actually planned or at least tolerated to regulate flow downstream or encourage people not to drive at all -- which driver advocates such as radio station WMAL traffic pilot Dan Rosenson, known to listeners as Captain Dan, see as discrimination plain and simple. "The attitude now is make life tough for these guys so they won't bring their cars into work," he complains.

Still, the consensus in area governments today is that at times traffic flow must take a back seat to other urban objectives such as clean air, the preservation of neighborhoods and fuel economy.

"We all came to learn over the last 20 years that you can't keep widening roadways," says Seward Cross, traffic engineering chief for the 1,100 miles of roads that the District of Columbia maintains. "You'd end up with no downtown," says Norman Ross, who manages timing of city traffic lights. "It would be all paved."

The era of pouring concrete is past. For future improvements, engineers are relying on tinkering with what's already there -- linking traffic lights by computer, making streets one-way, putting in left-turn lanes. At the same time, they hope to get more people into fewer cars or onto the Metro subway to decrease the load on existing roads.

Planners claim that some small progress has been made in reducing total traffic flow. Metropolitan Council of Government (COG) figures show that the number of cars entering the downtown core has dropped by about 4 percent since 1975.

Nonetheless, Washington congestion remains a case of too many cars in too little space. About 270,000 cars, buses, trucks and other vehicles cross the Beltway inbound every working day from 6:30 a.m. to 9:30 a.m., COG studies show.

Between those hours, about 170,000 vehicles stream into what planners call the "Metro core," a 14-square-mile area enclosing downtown, Crystal City and the Pentagon -- the area's main employment center. About 18,000 of the inbound vehicles use the 14th Street bridge alone.

Despite the development of Metrorail, Washington remains very much a city of rubber wheel transportation, with 260,000 people entering the core each morning by automobile, more than twice as many as arrive by public transit.

Traffic engineers, often protesting that the public doesn't understand the limitations they work under, argue that traffic of that volume cannot realistically be expected to move without delays. "You're going to hit the back of that crunch sooner or later," says Ross.

Cars pile up in three types of places: where two big roads cross, where two or more merge into one, or where a single roadway just can't handle the volume. Washington has an abundance of all three.

The intersection of Massachusetts and Wisconsin avenues demonstrates why crossings are bottlenecks. Thirty-two thousand vehicles on Wisconsin Avenue must somehow pass through more than 20,000 on Massachusetts. With no overpass and none planned, someone must always wait.

But even with overpasses, big roads cannot cross without a disruption of flow. For example, at the Shirley Highway-Capital Beltway interchange, which handles 227,000 vehicles on an average weekday, cars weave toward exit ramps, causing those behind them to brake. Accelerating cars getting into the traffic stream also cause it to slow.

The second type of classic chokepoint -- merging roads -- comes to full flower just north of Alexandria, where four lanes become two as East Abingdon Drive joins with northbound George Washington Memorial Parkway. "It's like when you pour three gallons of water into a two-gallon bucket," says Charles Kenyon, chief of Alexandria's transportation division.

Shirley Highway, which some days is more like a 10-mile-long parking lot between the 14th Street bridges and the beltway, is the monsterpiece in the third chokepoint category -- a segment of roadway that can't handle the load. Rte. 50 at the Four Mile Run bridge and at Carlyn Springs Road, where three lanes of roadway in each direction narrow briefly to two, is another example.

Other roadways flow relatively smoothly many days but are terribly unforgiving if anything unusual, such as breakdowns, rain, or sun in the driver's eyes. The Woodrow Wilson Bridge, for instance, has no shoulders. With more than 100,000 vehicles barreling across the bridge daily, a single disabled car can create a backup that extends for miles.

Collection points are the basic challenges of traffic engineering, which can offer clean solutions in textbooks but once on the street is buffeted by countless uncontrollables -- weather, accidents, stuck lights, driver impatience, or uncooperative officials in the next jurisdiction, for instance.

D.C.'s engineers treat congestion as inevitable but try to control where it occurs. One basic technique is to use certain intersections as sluice gates regulating the flow of cars that gets downstream. Backups on approach roads are considered preferable to a gridlock downtown.

For example, cars moving inbound on New York Avenue from Maryland back up at Bladensburg Road. They are held there, then released by the green light in groups (engineers call them "platoons") that are meant to advance as a cluster through a sequence of green lights without stopping.

Engineers complain that driver psychology undoes many of their efforts. For phased traffic signals to work, cars must maintain a uniform speed and stay in a cluster. However, drivers at the front of a group tend to press down on the accelerator when they see open pavement and green lights ahead. That puts them ahead of the cycle and forces them to stop.

Other habits that drive engineers mad: Illegal parking that closes entire lanes; drivers running yellow and red lights, which block intersections; and jaywalking (Cross says that D.C. studies have shown 60 percent of all pedestrian crossings violate the law in some way.)

Twenty years ago, the common approach to relieving traffic overload was to build more roads. In the 1960s and early 1970s, plans were on the books to build elaborate loops of expressways in the District, linked to the beltway, with Rte. I-95 passing through the center of town.

Then came the oil crisis and the environmental movement. The belief that highways were too expensive, drove people from their homes and served to generate more traffic and pollution gained strength.

In the District, only the Southwest Freeway and a few other segments such as the I-395 tunnel underneath the Mall were built. About $2 billion in federal money committed to D.C. interstates was diverted to Metrorail construction.

Maryland canceled segments, too. Virginia remained the truest to the highway, upgrading Shirley Highway and building, with much delay, the extension of I-66 to downtown from the beltway.

Today, two other big highways -- the Springfield bypass in Fairfax County and the "intercounty connector" linking Prince George's and Montgomery counties -- are glimmers in planners' eyes. For the most part, governments are concentrating their limited funds on improving what they have.

One goal, as it happens, is to clear blockages created by the abandonment of the interstates.

For instance, with Rte. I-95 from Baltimore planned to run through to downtown, the interchange at the beltway in Prince George's County was designed with through traffic in mind. However, I-95's inner segment was never built, meaning that cars arriving from the north must turn right or left on single-lane ramps onto the beltway.

Daily backups result. The Maryland highway administration is working on plans to improve the exit ramps. But construction, estimated as costing $17 million or so, is not likely to begin before fiscal 1985.

Modernizing traffic-light controls is viewed as another comparatively cheap way to quicken traffic flow, though it has limitations. D.C. has just awarded a contract for the design of a $34 million computerized system for its 1,250 intersections that have signals. In Alexandria, 130 intersections are now on line, with work proceeding in Arlington, Fairfax, Prince George's and Montgomery counties to improve synchronization.

Meanwhile, Virginia is attempting to apply computer technology to Shirley Highway and I-66. Starting in 1983, computers using pavement sensors will monitor traffic flow and activate red lights at the ramps to limit access to the main highway until there is room, and it is hoped, reducing overall delays.

Engineers have countless other projects on the books to upgrade existing roads. Virginia is now building an extra lane each way on Shirley Highway between Duke Street and Glebe Road and plans to widen Rte. 50 at Four Mile Run and Carlyn Springs Road bridges, for instance.

Maryland and Virginia this year raised gasoline taxes and D.C. is putting more federal money into roads, but funding remains tight all around. And even when money is there, the bureaucratic realities of the multijurisdictional Washington area make work move slowly.

The redecking of Chain Bridge, for instance, requires coordination of the D.C. government, which owns the bridge, the U.S. Park Service, which controls access on the D.C. side, and Virginia state government, which oversees access roads on that side. With U.S. taxpayers paying for the job, federal officials also get into the act.

Moreover, the different parties at times have conflicting goals. D.C.'s recent efforts to reduce traffic on residential roads such as Reno Road and 13th Street NW, for instance, have met with some protest from Montgomery County, which wants to keep open roadways for its commuters to downtown.

Steps like these tend not to solve a congestion problem, but to relocate it. "Take it off one street and it's going to go somewhere else and affect someone else," says Montgomery County traffic engineer Scott Wainwright.

So increasingly, in a variation of lowering the river instead of raising the bridge, planners are looking for ways to reduce traffic rather than expand the road.

A prime effort is Shirley Highway's reversible express lanes for buses and cars carrying four or more people. They flow briskly at peak hour, while regular lanes are backed up for miles. Officials call this an effort to encourage people to ride together (it can also be seen as intentional creation of jams on the nonexpress lanes). The express lanes carry close to 9,000 people per lane at peak hour, while the others move only about 2,400 people per lane.

Taking the concept a step further, I-66 will be open only to buses and "high occupancy vehicles" during peak hours on the grounds that this enormous investment would be wasted if single-passenger cars clogged it up. (The road is now open only to buses; private cars will be admitted starting in December.)

Other efforts in this direction include the COG's referral service to match people with car pools, which handles about 30,000 inquiries a year. COG reports some small progress in phasing out the one-passenger car. In 1975, cars entering the core area at morning peak hour carried on the average 1.43 people. In 1981 it had grown to 1.48.

Currently 39 miles of Metrorail track is operational, but COG transportation planner Ron Sarros said his agency believes that the continuing expansion of the rail system probably can't be expected to reduce road traffic, only to retard its growth.

Since the first Metro segment opened in 1976, the number of people entering the central core by automobile has held steady at about 260,000. But in the same period employment has increased markedly and Metro has picked up the extra load, with numbers entering on public transportation rising from 98,000 to 126,000.

Metro's escalating fares and troubled service have contributed to doubts about its effectiveness when competing with cars. Many commuters, especially those living in the outer suburbs, where Metro can cost $5 per round trip, prefer to go by car pool or drive alone.

Barring an oil embargo that would force gas prices up and commuters onto Metro, congestion on area roads is not likely to ease markedly in coming years. That means lots of teeth-gnashing and overhead engines, and a continuing challenge to the cunning of urban man in devising special routes and travel schedules to beat the crunch.

British Aerospace executive Leo Schefer, for instance, tries to leave either early or late when driving from his Manassas home to his company's downtown office. "If I leave Manassas after ten past six, I will get clobbered at the end of I-66," he says.

And taxi drivers, masters of the side street, will continue their search for shortcuts. Melvin Ailer, president of the Fraternal Order of Taxi Drivers & Owners and a driver since 1936, says, "People were complaining in 1936, too. But in comparison we were in heaven but didn't know it."