The Teamsters union that represents workers at both of Canada’s largest freight railroads has filed the lawsuits it promised challenging the orders that forced employees back to work.

Canadian railway operations have resumed after a brief work stoppage, following government intervention in an ongoing labor dispute.

TORONTO — The Canadian arbitrator appointed to resolve a railroad labor dispute to protect the North American economy has ordered employees at two major railroads back to work.

Canadian National Railway Co. spelled out a challenging picture for the economy as earnings fell short of expectations in the third quarter, partly due to falling demand for consumer goods.

Canadian National reported record second-quarter earnings that beat the expectations of Wall Street analysts.

Canadian National Railway Co. dropped the most in eight months after saying that Jim Vena, a former executive favored by shareholder TCI Fund Management Ltd. to run the company, had dropped from consideration to replace CEO Jean-Jacques Ruest.

The embattled CEO of Canadian National Railway announced his retirement on Oct. 19, the same day the company posted financial gains during a third quarter that saw its attempt to merge with Kansas City Southern fall apart.

Canadian National Railway Co. said it plans to cut spending, streamline management and buy back C$5 billion (about $4 billion) of stock next year as its tries to ward off a shareholder revolt started by TCI Fund Management Ltd.

Canadian National Railway reported an increase in second-quarter net income and revenue, and for the second period in a row company leaders spent significant time detailing for analysts the value of the company’s $33.7 billion merger with Kansas City Southern.

As leaders from Canadian National Railway and Kansas City Southern Railway promote their proposed merger, concerns are growing among some of their customers.