The future of an unprecedented Canada railway stoppage hinged on a decision expected Saturday from a federal labour board amid an ongoing, bitter contract dispute between the country鈥檚 two largest railway companies and the Teamsters union representing thousands of their workers.

Teamsters, Canadian National and Canadian Pacific Kansas City were all waiting on a decision after a 鈥渕arathon nine-hour hearing鈥� before the Canada Industrial Relations Board, the union said.

鈥淭he union will lawfully abide by any decision from the CIRB, and is prepared to file challenges in Federal Court if necessary,鈥� the union said in a statement issued after Friday鈥檚 hearing.

Freight shipments and some major commuter lines across Canada came to a standstill on Thursday when CN and CPKC locked out workers after months of increasingly acrimonious contract talks failed to yield a deal. It marked the first time there were simultaneous work stoppages at the railways.

Labour Minister Steven MacKinnon stepped in later that day, asking the labour board to send the parties to binding arbitration and to force workers back on the job while an agreement is hammered out.

MacKinnon鈥檚 directive said binding arbitration would produce a settlement to secure 鈥渋ndustrial peace鈥� and protect Canada鈥檚 trade relationships and sectors hit hard by the shutdown.

The board held meetings Thursday night and Friday, and has said it鈥檚 addressing the issue 鈥渨ith utmost urgency.鈥�

CPKC workers went on strike at the same time a lockout came into effect early Thursday morning. While CN lifted its lock out on Thursday, workers there could strike as early as Monday after Teamsters issued a 72-hour notice on Friday.

CN said service had resumed across Canada Friday morning and no major issues had yet been reported.

鈥淭he ramp up is continuing. We are focused on powering the economy and we call on the union to do the same and not take the Canadian economy hostage,鈥� spokesman Jonathan Abecassis said in an interview Saturday.

CPKC鈥檚 operations remained shut down as of Friday.

The Teamsters say both companies are attempting to weaken protections around rest periods, shift length and scheduling, jeopardizing worker safety. CN also has a plan to move some employees to far-flung locations for several months at a time to fill labour gaps, the union says.

The Teamsters have said the labour minister鈥檚 referral was unconstitutional and would 鈥渄estroy collective bargaining rights.鈥�

Jordan Omstead, The Canadian Press