Industry experts report that trucks have become warehouses on wheels, as stores and factories, aided by the Internet, have cut costs by shrinking the amount of production materials and consumer goods they warehouse. They rely on trucks to pick up goods the moment they become finished products and deliver them to customers when needed.

Such "just in time" scheduling and inventory control has made life more hectic for truckers.

• There are nearly 600,000 drivers of large trucks -- those weighing more than 10,000 pounds.

• Trucking company revenues are up more than 60 percent this decade -- to more than $400 billion -- and the number of trucks on the road has swollen 18 percent.

• Truckers haul 81 percent of the value of the nation's freight -- and 60 percent of the tonnage.

• Because truckers are in heavy demand, industry insiders say the average trucking company has an annual turnover rate of 100 percent.

In April, the Department of Transportation toughened its fines for rule violations by truckers -- such as driving too long and ducking safety measures. But some drivers say they routinely break the rules anyway.

Source: Peter T. Kilborn, "In a Non-Stop Economy, Truckers Keep Rolling," New York Times, November 24, 1999.