Ann Arbor, Mich., 5:09 p.m., a typical Tuesday afternoon in late 1996.

Marty Robinson has been scrambling since his shift started 99 minutes ago. As Con-Way Central Express’s line-haul dispatcher, Robinson has to gather and sort through a foot-and-a-half stack of mainframe printouts showing what freight needs to move between 200 locations across 25 states and Canada during the next 12 hours. Robinson reviews tonnage, available drivers and trucks, and trailer capacity at each of the 40 locations assigned to him. Like the other seven dispatchers sitting in a brightly lit tray of cubicles, he must plot the nightly routes that will transport 50,000 shipments of heavy freight on 2,100 trucks from their origin points to midway freight-assembly centers. (A midnight shift will route the freight from the assembly centers to its final destination.)

Con-Way’s model for line-haul?the movement of freight over long distances from service center to service center for redistribution?forces Robinson into a perpetual tug-of-war between the promise of on-time overnight delivery (a nonnegotiable customer expectation) and efficiency. For efficiency’s sake, he must build routes with the fewest miles, maximize trailer loads and make sure drivers, who are nonunion, can get home when their daily shift ends. The clock ticks insistently on the whitewashed wall that’s covered by maps of the Midwest. Robinson has 51 minutes left to finish the route plan and start typing his instructions to individual freight depots and their waiting drivers. But there’s a snag. He’s got two more freight units to ship from Indianapolis to Louisville, Ky., and he’s out of trailer space.

Robinson can reroute a truck from Terre Haute, Ind., to Indianapolis to grab the two units, but the truck would have to return empty to Terre Haute to meet its incoming load. That’s 130 nonrevenue miles.

He shouts to his neighbor John, visible over the low cubicle wall. "Have you got anyone in your area who can divert to Indianapolis for two units?"

No, John’s already short of drivers for Cincinnati. Robinson could keep checking, but he can’t afford the time. He eats the empty miles and shifts his attention North, to Chicago.

Actually, Con-Way’s line-haul dispatch job is even more complicated than the image drawn so far. For example, Robinson’s working with only 85 percent of the day’s freight orders. The rest come seeping in while he’s wrangling his route plan. And an ice storm he hasn’t yet heard about may shut down one of his cities, throwing another monkey wrench into his plans.