Rail car traffic is up about 5 percent across the board for the year among all different commodities, and petroleum car loadings are up more than 20 percent, he added.
There is also a low volume of spare rail cars in storage, and rail car productivity is challenged.
"It takes more rail cars to move a given quantity of goods," he said.
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On top of that, Vitale thinks Street estimates are light for both Greenbrier and Trinity.
Vitale has a "buy" rating on all three names—with a price target of $35 for Freightcar America, a $75 price target for Greenbrier and $52 for Trinity. He does not cover American Railcar, which has jumped 78 percent year to date.
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However, one of the drivers of the rail car sector's success is the shale boom, and if that goes bust "these stocks will react poorly," Vitale said.
—By CNBC's Michelle Fox. CNBC's Shartia Brantley contributed to this report.
Disclosure: RAIL, GBX and TRN are investment banking clients of Sterne Agee