Railbit is a common blend of bitumen and diluent used for rail transport. Railbit which contains approximately 17% diluents or less. compared to 30% in dilbit. Dilbit can be transported through pipelines but railbit cannot. To prevent solidifying in lower temperatures, both raw bitumen and railbit require insulated rail cars with steam-heated coils. Because it has a smaller percentage of diluents, railbit crude requires special capacity rail unload terminals capable of loading railbit and of handling larger unit trains. By the fall 2013 approximately 25% had that capacity. The U.S. State Department in their 2014 Final Supplemental Environmental Impact Statement (SEIS) regarding the proposed extension to the Keystone Pipeline, acknowledged that,