As required under the Pipeline Safety Act amendments that became effective on January 3, 2012, PHMSA commissioned the National Research Council to study whether shipments of diluted bitumen differ sufficiently from shipments of other crude oils in such a way as to increase the likelihood of releases from transmission pipelines.  Significantly, the Committee’s final report, Effects of Diluted Bitumen on Crude Oil Transmission Pipelines, did not find any causes of pipeline failure unique to the transportation of diluted bitumen.  In addition, the Committee did not find evidence of chemical or physical properties of diluted bitumen that are outside the range of other crude oils or any other aspect of its transportation by transmission pipeline that would make diluted bitumen more likely than other crude oils to cause releases.  In support of its conclusions, the Committee made the following three findings with regard to diluted bitumen: (1) it does not have unique or extreme properties that make it more likely than other crude oils to cause internal damage to transmission pipelines from corrosion or erosion; (2) it does not have properties that make it more likely than other crude oils to cause damage from external corrosion and cracking or from mechanical forces; and (3) pipeline O&M practices are the same for shipments of other crude oils.  Notably, the scope of the study was limited to transmission facilities and did not address whether pipeline releases of diluted bitumen differ in terms of consequences.