Due to the regulatory obstacles and lawsuits
Rail transport
One of those obstacles is that oil producers and refiners are increasingly choosing to transport the black stuff by rail. Rail cars in Canada carried 20 percent more oil in 2013 than they did in 2012. Due to the regulatory obstacles, lawsuits, various land holdings disputes (from private landowners to aboriginal land claims) and environmental assessments that prevent a pipeline from being quickly constructed, rail transport is an easier option even though it is in principal more risky. Oil shipment by rail generated 2 incidents per billion ton-miles annually, while pipeline shipment caused 0.6 incidents over the same time and distance.
Without more pipeline approvals, rail shipment could further increase. Although the U.S. already has 2.6 million miles of pipeline and Canada 511,500 miles, it is rare to see new monumental projects being undertaken equivalent to, say, the epically-named Power of Siberia pipeline, which will carry natural gas from Russia to China. Many of the major pipelines under discussion in the United States --Keystone XL and Northern Gateway, for instance -- have been debated for years, although it should be noted that the other three phases of the larger Keystone pipeline system have opened since 2010.