Shipments of oil via the nation's railroads tripled between 2011 and 2012; that growth will likely continue as oil producers seek alternative markets for the highest returns and refiners look to replace expensive foreign imports with cheaper domestic crudes. Pipelines still transport the vast majority of oil in the U.S., and therefore they currently take the vast majority of criticism for oil spills. In this video, contributor Aimee Duffy looks at the numbers behind the safety records for trains and pipelines, and ponders what investors should think about going forward.