Teamsters Canada Rail Conference has given Canadian Pacific Railway 72-hour strike notice, meaning 3,300 locomotive engineers, conductors and other train workers could walk off the job midnight on Saturday.

Union president Doug Finnson is in Montreal this week negotiating with CP, with the help of federal mediation, but says the union has not made headway on issues such as working conditions.

He is particularly concerned about the company not complying with collective agreements that require train crews to stop operating and rest after 10 continuous hours of work.

"CP is completely unable to provide the majority of our members with any sort of accurate information on when they are required to work," said Finnson in a statement.

Contract talks are to resume on Wednesday and Finnson said the union is determined to reach a deal.

The Teamsters aren’t the only CP union facing a strike deadline. Unifor, which represents 1,650 workers who perform safety inspections, brake tests and some repair and maintenance work, will be in a legal strike position with CP early Sunday morning.

'They could try and run some, but they would never be able to provide the level of service that more than 3,000 professional railroaders provide.' - Doug Finnson, president of Teamsters Canada Rail Conference

However, that union has not issued the required 72-hour strike notice.

Even with just the locomotive engineers and other train workers on strike, the disruption of service would have a widespread effect.

Wayne Benedict, a former railroader and labour lawyer, said that CP has been training office workers and managers to operate the trains, so the company would likely try to continue operations to some degree.

Finnson said that won’t be effective.

"They could try and run some, but they would never be able to provide the level of service that more than 3,000 professional railroaders provide."

"If history is any judge we would expect to see back-to work-legislation from Ottawa," said Benedict.

In 2012, the Teamsters Canada Rail Conference members were on strike for nine days before back-to-work legislation passed. But in that nine days, a huge backlog developed of freight such as grain and other commodities.

At the time, then labour minister Lisa Raitt said such a strike would cost the economy $540 million a week.

The Canadian Press contacted the office of current Labour Minister Kellie Leitch, but did not hear back.

Also this week in Montreal, the Canadian National Railway is in contract talks with the Teamsters for 1,800 locomotive engineers and with Unifor representing 4,800 other workers. No strike vote has been taken yet.

With files from The Canadian Press