The world's greatest game of chicken was in full swing.

The ancient, rattling bus rambled across two lanes and took a sweeping turn, landing smack in front of an oncoming taxi.

Jerking back his olive flack jacket, the young cabbie pulled a revolver from a waistband holster, lowered the window and took direct aim at the bus driver.

"I hope you don't mind, sir," he said, glancing back at a stunned passenger.

Welcome to midday traffic in Tehran.

IN A CITY that engenders few superlatives, visitors can't say enough about the traffic -- all bad. Even hardened travelers, who have sputtered in Cairo jams and Lagos pileups, insist that Tehran deserves first prize for chaos.

An aerial view of Tehran would look like a mosaic of metal -- small sausage links undulating through town.

On the ground, it looks like a street riot.

Virtually every major road is clogged all day. In fact, the auto cognoscenti here like to travel the alleys, which serve as a kind of underground network.

Traveling 90 miles from Tehran to the holy city of Qom normally takes 90 minutes, border to border. But the drive from downtown Tehran to its boundary line can take just as long.

A passenger traveling a few miles in rush hour is well advised to curl up for a nap.

BUT STAYING awake guarantees a thrill a minute, like riding a roller coaster that switches tracks when least expected.

No one changes lanes with more than a few inches to spare, and very often bigger cars simply force their into the next lane with no more warning than a honk.

Lanes? On a two-way street, traffic often moves in three or four directions -- alternating lanes of northbound and southbound movement. At hectic times, channels reverse themselves with southbound traffic suddenly driving in the northbound lane and vice versa.

Somehow, vendors manage to weave through this incredible procession hawking Winston cigarettes, car mats and flashlight battery sets. Beggars follow, reaching right through the car window with outstretched hands.

Sidewalks are in limits during rush hour, and desperate drivers will even move backward to gain strategic positioning. Stoplights might just as well not exist.

A manual on driving in Tehran might give the following advice to drivers attempting a left turn: move into the far right lane, lean on your horn and then cut sharply left.

IN THE GHETTOS of south Tehran, herds of sheep grazing in urban trash piles frequently wander into the road, adding to the clutter. Pushcarts of food or freight move in the same lanes as four-wheeled autos.

The result of all this is a constant spaghetti-like tangle, accompanied by a symphony of horns.

Accidents are as common as a cold, and few cars survive long without dents, scrapes or scratches. The proud owner of a new Iranian-assembled Peykan drove out of the plant recently only to be sideswiped within minutes.

The state of traffic control here is not necessarily a byproduct of the city's revolutionary fervor. Most old hands say congestion was about as bad under the tightly controlled regime of Shah Mohammad Reza Pahlavi, although last February's rebellion shredded the ranks of traffic police.

It is a rare sight today to see traffic cops, and when they do take their places on the battle lines, they hardly make any difference. Sometimes, self-appointed citizens try to regulate traffic, usually making matters worse.

That is not to say that the Islamic government of Iran ignores the traffic jumbles of its busiest city. Last spring, the mayor of Tehran was executed for a long list of charges, including his failure to improve traffic flow here.

IN THE TRAFFIC wars of Tehran, the real gladiators are the taxi drivers, a stoic bunch who hone their skills with surgical precision. Not even flinching at a near miss, they shrug off the kind of bumper-to-bumper aggravation that would ruin an entire day for the Washington commuter.

When you step into a Tehran cab, you often get a choice of driving styles: fast, faster or still faster.

The best strategy: sit back and enjoy the ride.