Workers at Winnipeg's Symington Yards — one of the largest rail yards in the world — are walking the picket line.

They walked out Monday at 11 p.m. CT, joining about 3,200 Canadian National Railway conductors, trainpersons and yard workers across the country after the union and company failed to reach a deal by a midnight ET deadline.

The Teamsters Canada Rail Conference, the union representing the employees, gave the required 72-hour strike notice on the weekend.

CN officials have not said how the strike will impact Symington, which is the company's largest marshalling yard, where freight trains are divided and reassembled according to their destinations.

Symington Yard can store 7,000 cars and handles 3,000 cars per day.

The sun rises as workers strike at CN's Symington Yard in Winnipeg. (Meaghan Ketcheson/CBC)

"We are disappointed that the TCRC has initiated strike action, which will result in a significant disruption to service," Janet Drysdale, vice-president of financial planning for CN Rail, said Tuesday morning in Toronto.

"We apologize to our customers but we do appreciate their understanding that safety is always our first priority. Negotiations are expected to continue later today, under the watchful eye of federal mediators."

Economy faces big hit

Barry Prentice, a transportation expert at the University of Manitoba, doesn't expect the strike will last too long.

Historically, governments have stepped in to end rail strikes before the economy takes a hit, he said.

"Fifty per cent of all our goods move on rail, and to have that impact on the economy very, very quickly adds into the millions of dollars," he said.

Prentice expects most companies relying on rail can get along for a few days or a week, but soon, inventory will begin to run out.

Meanwhile, those who need to transport goods by rail will run out of storage.

The agriculture industry in particular could take a hit from the strike, warns Keystone Agricultural Producers.

Farmers already had to endure a dry summer, then an incredibly damp fall that included a major snowstorm right around harvest time.

Kevin Stott — who farms near Niverville, Man., and is on KAP's transportation committee — said the rail strike could further jeopardize farm incomes.

"Everyone's bins are full and they're trying to move some product to get some cash flow going, to pay off some operating loans," Stott said.

"If it's just short-term, it's not going to affect that much. We understand they're still talking to each other, which is a good sign, but nobody said whether they thought it was going to be a two-day or two-month strike."

A strike lasting a month or longer could have a significant impact on farmers, he said.

Teamsters Canada Rail Conference spokesperson Christopher Monette said the union is still in talks with CN in hopes of reaching a negotiated settlement and ending the labour dispute as soon as possible.

The workers, who have been without a contract since July 23, said they're concerned about long hours, fatigue and what they consider dangerous working conditions.

"We have members out there who are operating trains when they should in fact be resting," Monette told CBC News after the strike began.