The department is prohibiting both men from driving commercial vehicles in the United States, alleging that speeding played a part in the crash that killed nine and injured dozens more.
The U.S. regulator body says Mi Joo Tour & Travel's driver Haeng Kyu (James) Hwang was driving too fast for road conditions when he lost control on icy roads and his bus plunged down an embankment.
A second driver on the trip working for the Coquitlam, B.C., bus company, Choong Yurl Choi, is also accused of driving too fast for conditions.
The department says both drivers were also found to have been driving well beyond the 70-hour limit over a seven-day period.
Police have not yet said what caused the Dec. 30 crash, so the federal department's assessment of excessive speed is the first suggestion of what may have contributed to the tragedy.