WASHINGTON, D.C. — The National Transportation Safety Board (NTSB) has issued its full report on two high-profile school bus crashes that occurred in November 2016.

The special investigation report — titled “Selective Issues in School Bus Transportation Safety: Crashes in Baltimore, Maryland, and Chattanooga, Tennessee” — was the subject of an NTSB meeting in May. Board members adopted probable cause statements and recommendations related to the two crashes, in which a total of 12 people were killed and 37 were injured.

On Friday, NTSB announced that the full report is now available. The 119-page document includes details on each crash, driver oversight issues, findings on school bus occupant protection and crash prevention technologies, conclusions of the investigations, and the agency’s recommendations.

In the executive summary of the report, NTSB draws a key parallel between the Chattanooga and Baltimore crashes.

“Although the specific safety issues differed, the crashes shared one common factor: poor driver oversight by both the school districts and the contracted motor carriers, which resulted in unsafe operation of the school buses,” the agency says in the report.

NTSB also notes that while “school buses are extremely safe,” more can be done to reduce the potential for future losses like those in Chattanooga and Baltimore.

“Improved oversight of school bus drivers and enhancements to school bus design — such as installation of passenger lap/shoulder belts, electronic stability control, and automatic emergency braking — could prevent or mitigate such crash outcomes.”