The pulse of railroading used to beat to the urgent but predictable cadence of too little time chasing too much space.

Anyone who wore a trainman's pocket watch tucked into his black-and-white striped coveralls understood that - and could describe, with great precision, the calculus of promises to keep.Kimberly at 4:10. Hansen at 4:20. Burley at five of five.

But on this particular ice-bright Wednesday afternoon, with late winter seeping through the locomotive cab's safety glass, Chris Centracchio speaks of time unfilled.

"Five or six hours," he muses, easing 135 tons of locomotive westward at the pace of a brisk walk. "That's what's left of the day. We're not allowed to work longer than 12 hours a shift, but that's not a problem very often."

Conductor Ed Cullinan charts military time in neat squares on a clipboard, then slips out the door to bulldog 50 tons of molasses onto a siding and out of harm's way.

"We have to make sure we get our work done when we're supposed to, and the company keeps careful track of that," he said. "But there's no timetable for us to be at a certain place at a certain time."

Centracchio and Cullinan are heirs to the brawny business of steel-against-steel, a trade that used to employ thousands and edify millions.

Now, like the rest of the automated, digitized, information-age railroad industry, the Eastern Idaho Railroad Co. traffics in customization - commodities plucked from a rail siding here and routed with Fed Ex-style precision to a customer across the continent.

Yet here on the ground, it's a job done in increments of 30 yards, 5 mph, and a half-dozen cars shuffled like a three-deck shoe through the fingers of a European croupier.

"I like the fact that I can go to work every day at the same time and expect to get done about the same time," said Centracchio, a 10-year railroader who's been with the EIRA since it sank stakes in Twin Falls. "Not like the old days. When I was working long-haul routes, I had a three-day layover."

The mystique is largely gone from Centracchio and Cullinan's craft in an era when a five-person crew can run a 100-car train. The equation of the work nowadays is one part diesel, two parts physics and three parts microchips.

But some of the charm persists.

"Kids still wave to us all the time when we roll past," Cullinan said.

"And if we're stopped at a crossing too long, the parents wave at us too," Centracchio quipped.

Still, neither would swap this locomotive for a beet truck or computer keyboard or eight hours on a factory lathe.

"Unlike some kids, I didn't grow up wanting to work on the railroad," Centracchio said. "But I wouldn't want to do anything else now."