COLUMN ONE : Passing ‘Go’ in Bosnia Tests Nerve : Checkpoints dot the war-torn republic’s back roads. Some are guarded by peacekeepers. But at many, travelers confront hijackers, extortionists and drunks with guns.

“Stop. No U.N. soft-skin vehicles beyond this point without escort. We care for your safety. PAKBAT.”

As bleeding Bosnia-Herzegovina lurches from crisis to crisis, it is, as ever, hostage this summer to a dangerous checkpoint culture. In the Bosnian outback, it is too often checkpoint-stealpoint: The rule of law becomes tenuous in a country riven by war and ethnic division.

Checkpoints are arbitrary, and scary to everyone who must pass through them. They are microcosms of the awful unpredictability of life in a war zone, where routine and tragedy can seesaw without warning.

Here on a mountain curve an hour from the northern Bosnian city of Tuzla, the U.N. control point staffed by a Pakistani battalion--PAKBAT--is a welcome aberration: It is meant to help.

On this stretch of bad road, at least, the presence of blue-helmeted Punjabis discourages the more usual sort of Bosnian highway patrol: hijackers, extortionists, drunks with guns, criminals in ragtag uniforms; hot, bored, hungry and ill-disciplined young soldiers of one side or another.

Sometimes they take out their leaders’ political frustrations on travelers. Often they inflict their own anger and avarice. Whim often wins, so it takes an expert to keep score: In the Bihac pocket of northwestern Bosnia, where fighting has been heavy, six armed forces are battling for control of territory and roads.

Here, along a roughly two-mile stretch of dirt road exposed to hilltop Serbian guns, the doughty Punjabis run a crisp shuttle. Drivers are obliged to don helmets and flak vests and ride behind armored cars. Passengers are bundled into an armored personnel carrier for a hang-on, high-speed, sardine-tin gallop through the danger area.

“The pucker factor is pretty bad the first time, but after that you begin getting used to it,” said Bob Nelson, a volunteer for an American relief agency who drove the road one recent morning, dodging shell holes and sticking close to the Pakistani armored car leading the pack.

Checkpoints come and go, more nuisance than threat. Until suddenly one goes bad. Bosnian life is like that too. Tuzla, case in point, is a Muslim “safe area” in northern Bosnia little affected by war. But without warning on May 25, high school graduation day, Serbs shelled the city’s packed main square, killing 71 people and wounding 165.

Where there are no U.N. troops on Bosnian roads, the anxiety never lets up. Not far from the PAKBAT shuttle is a Bosnian government checkpoint at the junction of two dirt roads that have become main routes for international convoys.

One recent morning, belligerent and thirsty Bosnian soldiers calling themselves Black Swans waylaid a convoy of Scandinavian aid supplies.

The convoy leader, a young Norwegian civilian, was still shaking half an hour later. “They said the paperwork was no good. I said I would fix it. ‘Impossible,’ they said. They would be obliged to take my two passengers, government officials visiting from Sweden. Can you imagine losing two government officials? Off into the woods with the Black Swans?

“I begged. They wouldn’t relent. Until finally, one soldier said, ‘OK, give us some beer and cigarettes and you can pass.’ ” The Norwegian nervously puffed a cigarette under watchful Pakistani guns. The two Swedes, sweating through body armor, looked distinctly pallid.

Since cars or trucks traveling alone are the easiest mark for checkpoint crooks, drivers form convoys in exactly the same way and for exactly the same reasons that settlers once moved by wagon train through the American West.

A convoy can be psychologically reinforcing. Usually it is also physically protective. But sometimes it is not enough.

“Pulling up to a checkpoint I was in a 4-by-4, the last vehicle. I thought nothing of it until a couple of criminals in uniforms stepped out in front of me,” recalls Dirk van Gorp of Schroon Lake, N.Y., who directs Bosnian aid programs sponsored by American Methodists.

“As the convoy pulled out, they let off a few rounds, separating me. The message was clear. I jumped out and said, ‘Please accept this gift from the United Nations through me to you.’ After a while, the convoy realized I was missing and somebody came back to get me,” Van Gorp said.

Sometimes highwaymen are threatening, and sometimes they are almost apologetic when they drive off. Occasionally they are even helpful, as they were Thursday when a U.N. armored car spun off a dirt road into a ravine near the eastern Bosnian town of Zepa.

“Bosnian Serb soldiers were extremely helpful in helping to recover the vehicle,” U.N. spokesman Christopher Gunness said in Zagreb, the Croatian capital, on Friday. “Then they stole the vehicle, the ammunition and the weapons.”

To lower the odds of losing a vehicle or a humanitarian cargo, convoy leaders for private aid groups often carry caches of German marks for bribes. They sometimes also are accompanied by young Bosnians, many of them women, who are nominally interpreters but are also diplomats in dealing with checkpoint soldiers.

“They know when to flirt and when to wheedle. They are smart, and they are very brave,” said Michael Taylor, the British coordinator for an American aid group.

Sometimes, as the interpreter weaves her spell at a checkpoint, a convoy leader will relieve the tension he knows is building in the vehicles behind him. The soft-spoken radioed assurance “No problem here; they’re just talkin’ ” is like a drink of sweet water on a hot afternoon.

When the hard-pressed Bosnian government is particularly angry at the United Nations, getting through a checkpoint becomes an endurance trial. The line of U.N. vehicles awaiting permission to clear a checkpoint can last for miles--and days.

On the other hand, when blockage is more arbitrary than political, it is time for psychological warfare, said Michael Rowlatt, logistics director for the New York-based International Rescue Committee.

“Drivers quickly learn to pretend that being stopped is of no consequence. One will put a towel on the hood, take off his shirt and take some sun. Others may play catch with a Frisbee or kick a soccer ball. We had one driver who liked to practice with his skateboard if there was a bit of pavement around,” Rowlatt said. “Eventually the keepers of the gate realize that their harassment is backfiring, and they wave us on.”

At that point, Rowlatt said, checkpoint theatrics demand that actors leave the stage with dignity. “ ‘Right, we’ll go, but hang on, I just want to finish this page . . . hear the end of this song.’ . . . That sort of thing.”

As a general rule, Rowlatt said, it is best to get through as many checkpoints as possible as early as possible--before the heat of the day.

“Drinking is a problem, and early they are sometimes still sleeping it off. But they are always armed and always potentially dangerous,” Rowlatt said. “More than once I’ve found myself on the ground with a Kalashnikov in my ear and some yahoo yelling in a language I didn’t understand.”

Roman Catholics and Muslims in Bosnia are now joined in an uneasy federation that has diminished checkpoint danger in the central part of the republic. When they were fighting in 1993, as Australian trucker Chris Wilson put it, “everybody with five mates and a gun had his own checkpoint.”

In recent weeks, the cruelest checkpoints have been in northwestern Bosnia, where Croats, Serbs and Muslims in half a dozen armed permutations are grappling around the Muslim enclave of Bihac.

Brad Buscetto of San Francisco, who works for the United Nations’ World Food Program, got a double jolt of checkpoint culture in the Bihac area earlier this year.

“We were stopped at one Serbian checkpoint and told we had to go back to the last one to get a missing piece of paper. I knew right away we were in trouble,” Buscetto recalled.

“Sure enough, on our way back through the woods we were cut off by two cars. Guys got out with guns, said, ‘Sorry, we need your car,’ squirted us with tear gas and left us to find our way back through a forest full of mines.”

Buscetto emerged unscathed. So did the vehicle, a nifty white 4-by-4 with state-of-the-art radios.

“I’ve seen the car since,” Buscetto said with a wry smile. “It’s had a good paint job--camouflage colors--and belongs now to a Croatian Serb village commander. It looks really nice.”