You can look at Union Pacific's (NYSE:UNP) second-quarter results in two ways. You can give this Western rail operator hearty praise for strong revenue growth and improved operating efficiency. Or you can point out that they've been poorly run for long enough to make the bar artificially low, and they're still not performing up to par with their peers.

Whichever way you view it, revenue did jump another 17% this quarter, and once again the components of that growth nearly came down to thirds -- volume added 5%, better pricing added 6.5%, and fuel surcharges added the rest. And to the company's credit, they continue to shave down an industry-worst operating ratio -- lowering it to below 82 this quarter and subsequently seeing operating income jump 53%.

It was disappointing, though, to see less progress on asset utilization numbers. Velocity was stable from last year and last quarter. Though dwell times were improved sequentially, they were slightly higher than last year and well above rivals. In fact, Union Pacific's average dwell times are nearly 10% higher now than those at CSX (NYSE:CSX) (hardly a great operator themselves) and more than double those at Canadian National (NYSE:CNI), though that comparison isn't quite fair to Union Pacific.

So long as rail operators like UP can push through better pricing and continue to make operating improvements, good earnings should continue rolling down the track. And if, by some miracle, fuel prices ease up, they'll get an even bigger boost. The question, though, is how realistic that is. I mean, doesn't there have to be a limit to what Ford (NYSE:F) or Archer Daniels Midland (NYSE:ADM) can (or will) pay for freight?

Then again, as long as they control the rails -- and we don't see truckers slashing pricing or consumer demand tanking -- they hold a lot of the cards. Keep an eye on operating efficiency going forward, though, since the most efficient operators are the ones with the most flexibility on rates.

I certainly am no fan of UP and don't really see why it should get an above-sector valuation. Yeah, I get that they're turning around and more likely to produce gaudy growth figures, but I don't see why a company like BurlingtonNorthernSantaFe (NYSE:BNI) or NorfolkSouthern (NYSE:NSC) doesn't deserve just as much consideration.

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Fool contributor Stephen Simpson has no financial interest in any stocks mentioned (that means he's neither long nor short the shares).