Railcar manufacturer Greenbrier (GBX 21.17%) used strong cost management to easily top expectations and raise profitability guidance for the year.Investors are relieved, sending shares of Greenbrier up 20% as of 12:30 p.m. ET. Making the most of a tough environmentIt is a tough operating environment for railroads, with volumes down due to economic uncertainty and the impact of tariffs. In times like this, you don't normally see railroad companies making big capital expenditures, and shares of supplier Green ...