A national rail stoppage is looming across Canada after the two largest railroad operators issued lockout notices to their unionized workforces over the weekend. Canadian National Railway (CN) and Canadian Pacific Kansas City (CPKC) have notified the Teamsters union representing 10,000 workers that they plan to lockout workers starting on August 22.However, the lockout notices come after the Teamsters, which represent yard workers, locomotive engineers and conductors, issued 72-hour strike notices to both companies. A shutdown of the national rail network that stops freight shipments could have…