The road damage may be caused by bad construction, but even the best contractor would be challenged to build a highway that could withstand the severely overloaded trucks that regularly travel East Africa's roads.

Transporters said they routinely overload trucks in East Africa, paying off weigh-station clerks who are supposed to be protecting public highways. Kuria's boss, Anwar Bayusuf, the operations manager of M.A. Bayusuf & Sons Ltd., said that until recently he typically overloaded his trucks by 50 percent.

The company's customers and drivers say Bayusuf is being modest. The humanitarian organizations that contract Bayusuf to carry food aid said his company's trucks often arrived at their destination with twice the legal limit of 35 tons of cargo.

Kuria, the truck driver hauling a load of sorghum grain to Sudanese war victims, said he has hauled as much as 77 tons of cargo.

Trucks wait to enter Uganda from Kenya at the town of Malaba. Paperwork on both sides of the border can cause a delay of several days.

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The result of the corrupt practice is that transporters made huge profits at the expense of the road system, destroying it so thoroughly that Kuria must slow down to walking speed to get through the broken pavement. The economic costs of time lost and vehicles damaged by such roads is incalculable.

Two years ago the International Monetary Fund refused to lend any more money to Kenya, partly because corruption had become so blatant it was holding back the nation's economy. Since then, Kenya has taken action to curtail corruption, and overweight trucks are no longer tolerated.

"No more overloading," said Bayusuf. "I have too many trucks. I can't risk it. You know why we're doing this? The IMF has gotten too smart for us."

The IMF and the World Bank have begun to recognize corruption as a drag on economic growth and a threat to democracy. The international lenders have asserted themselves to force nations to address endemic corruption.

They have singled out Kenya for particular criticism, partly because corruption under President Daniel arap Moi's government has increased but also because Kenya is relatively well developed and has much to lose if its infrastructure is allowed to deteriorate.

The criticism seems to be having results. Yesterday The Nation newspaper reported that "panic has gripped civil servants" in Kenya because of the pressure to root out corruption.

"Apparently, there is stiff competition among the anti-graft arms in government to catch some big fish in an effort to prove to skeptical Kenyans that they are dead set on fighting graft," the newspaper reported.

But corruption is difficult to wipe out overnight. Many people expect a gratuity for doing their job. It's known as TKK - Toa Kitu Kidogo in Swahili. "Give something small."

As he drives along Africa's highways, Kuria is often stopped at police roadblocks and asked for gratuities. On this trip, he said he is grateful to have a white foreigner in his truck because the police treat muzungus with deference.

"If they see a muzungu, they wave you through," said Kuria as he glided through a checkpoint. Even in post-colonial Africa, white people often get preferential treatment.

Along the highway, the bribery system is well entrenched. Kuria never paid off weigh-station clerks himself. Rather, Bayusuf sent "clearing agents" to deliver the cash ahead of the truck's arrival. When Kuria arrived, he would be waved through.

Humanitarian organizations and United Nations agencies such as the World Food Program, which are often funded by international donors such as the U.S. government, can't submit bribes to donors for reimbursement.

"What we do instead is to hire clearing agents," said Joern Lose, the logistics officer for the World Food Program in the Kenyan port of Mombasa. The clearing agents do their dirty work, and the cost is reported as an administrative fee.

Early yesterday, as Kuria departed from his roadside parking space in Bungoma, Kenya, the rear brake on his trailer locked up. He blew a tire - one of 26 on the seven-axle rig.

Rather than repair the flat on the spot, Kuria decided to hurry to the border to get into a long line of trucks queuing to cross the border into Uganda.

Malaba, the border town, is a depressing place where cows graze in trash-strewn lots and most of the people at the border post look grim and hardened. Everyone seems to be looking for opportunities. Young men offer to ease the hassle of passport control for a fee.

There are so many trucks nudging through the border checkpoint that the air is choked with great clouds of black diesel fumes and dust. The EPA would probably shut down this place if it were in the United States. Here, nobody pays much mind.

Kuria was greeted at the border by Bayusuf's clearing agent, who grabbed a stack of police and customs documents placing the value of the cargo of 35 tons of grain at about $5,000.

The clearing agent ran off with the paper to get customs approval. Not once since the truck left Mombasa on Saturday has any authority lifted the tarpaulin to confirm the cargo is actually grain.

Kuria eased his 50-foot truck through the scales. Once he was clear, he slowly drove across a bridge separating the countries. By 11 a.m., four hours after he arrived at the border crossing, Kuria had cleared the scales in Uganda. The worst was yet to come.

The Ugandan border is notoriously slow for trucks carrying cargo to other countries, such as Sudan. It is a minimum of one night and can often take more.

Once cleared, a truck carrying cargo through Uganda cannot simply drive off. It must wait until the next morning for customs documents to be transported to Kampala 150 miles away. Then drivers must take their trucks to Kampala and check in with customs to confirm that they are still carrying cargo and have not unloaded goods in Uganda without paying duty.

Kuria's fortune ran out when a customs agent demanded he produce the truck's log book, a document proving ownership. Such a document doesn't normally travel with the truck and it was not required a month ago when Kuria crossed the same border. But the customs agent would not budge.

And so Kuria parked his truck in an undulating moonscape of dirt that looked like a refugee camp for big rigs - more than 100 trucks were parked there, waiting to be unleashed.

"Maybe we'll leave Thursday," Kuria said hopefully after telephoning his home office in Mombasa to consult about the documents.

Maybe not. Kuria's son, James, the assistant on the truck, in the afternoon removed the punctured rear tire and discovered that the brake drum was damaged. Another call was put into the home office in Kenya, demanding the delivery of spare parts.