The TSB issued a rail safety advisory to Transport Canada, calling on the regulator to pay closer attention and to review CN Rail's "risk assessments" for the northern railway line. TSB investigators concluded track failures contributed to the string of crashes — all within the space of a month — near Gogama, Ont., including one March 7, 2015 incident in which 39 rail cars derailed, caught fire and spilled crude oil into the Makami River. Investigators found worn rail at that site, which the TSB determined likely contributed to the crash. The TSB has investigated 13 major derailments in the past decade where investigators concluded track failures, poor maintenance and failures in oversight by Transport Canada were the primary cause. Only two of those derailments involved Canadian Pacific.