“As oil by rail shipments have increased in recent years, there has been a dramatic increase in the number of incidents involving crude oil by rail. Nationally, rail incidents rose from several per year prior to 2010 to 155 in 2013, and 90 thus far in 2014. More crude oil by volume was spilled
in rail incidents in 2013 than was spilled in the nearly four decades prior.
California is experiencing similar trends, albeit on a smaller scale to date. Incidents involving oil by rail in California increased from 3 in 2011 to 25 in 2013; as of May, there have been 24 thus far in 2014.Total petroleum spills by rail in California (crude oil and other) increased from 98 in 2010 to 182 in 2013.
Most reported incidents document a relatively small volume of oil released, but as detailed below, the potential for high-consequence incidents will increase as
more oil is transported by rail.”

http://www.caloes.ca.gov/HazardousMaterials/Pages/Oil-By-Rail.aspx