The conductor, train train, and yard yard from Canada gave notice of the strike before Tuesday's deadline.
The union, which represents 3,200 workers, gave 72 hours notice on Saturday when contract negotiations continued this weekend.
The Canadian Rail Teamsters Conference warned in October that it was ready to launch a working action after more than six months of failed talks.
The strike can begin at 12:01 ET on Tuesday now after the notice is given.
Workers, mostly in major urban centers in Canada, have been without contracts since July 23.
Rob Reilly, CN's executive vice president and chief operating officer, said in a statement the company would continue to negotiate "in good faith" in the coming days.
"If a settlement cannot be reached this weekend, we will once again encourage union leaders to accept binding arbitration as an alternative to disrupting the Canadian economy."
The strike notice came a day after the Montreal-based CN confirmed the reduction in work, saying it was "adjusting its resources to demand." CN won't say how many people will be affected.