Pipelines carry much more crude than trains and have fewer leaks per mile, though failures can be serious. In 2010, for example, an Exxon Mobil Corporation pipeline spilled 1,500 barrels of oil into Montana's Yellowstone River in an hour. The possibility of oil spills from derailments is only beginning to be on the public's radar.
From 2008 to 2012, daily U.S. oil production has grown to an average of 6.5 million barrels, its highest level in more than 15 years, according to the Energy Information Administration. It is expected to grow to 7.3 million barrels a day this year and to 7.9 million barrels in 2014.
The surge comes thanks to a combination of technologies—horizontal drilling and hydraulic fracturing, or fracking, which involves pumping water, chemicals and sand down wells to break up rock formations. The increased production, much of which has occurred in remote areas of North Dakota and South Texas, has outpaced the ability of companies to build new pipelines or expand existing ones to move the oil to refineries.
Historically, railways have spilled more oil on a gallons-per-mile basis than pipelines, according to several studies. One 2009 analysis of oil spills between 1980 and 2003 done for the American Petroleum Institute by Environmental Research Consulting found 80 out of every 1 billion gallons transported via rail spilled, compared to 38 out of every 1 billion gallons transported via pipeline. (WSJ, 3/27/2013)