Blue-collar workers demonstrated outside Montreal City Hall on Monday, the first of 40 days of planned walkouts. (CBC)

Montreal blue-collar workers launched the first of 40 days of rotating strikes on Monday.

City workers in the downtown Ville-Marie borough gathered outside city hall to call attention to the strike, which began at midnight.

The strike put a halt to road repairs and garbage collection, and forced the closure of some sports facilities.

Crews continued to salt roads and will clear snow when more than nine centimetres is forecast, according to the union plan approved by Quebec's Essential Services Council on Friday.

Montreal’s 5,000 blue-collar workers have been without a contract for more than two years, and Mayor Gerald Tremblay has vowed not to give in to the union's demands.

The union and the city are at odds over salaries and subcontracting. The workers are asking for a salary increase of nearly 10 per cent over four years. They are also demanding the city cut back on subcontracting to private firms.

"Personally, what I would say to [Mayor Gérald] Tremblay is, let's talk — there is a way to reach an agreement," said Norman Weaner, who works in the Ville-Marie borough.

But the union has been "unflexible and unwilling to move," countered Coun. Marvin Rotrand.

"The reality of the situation is the blue-collar workers are asking for more than every other union," said Rotrand, who is the leader of the majority on city council. "If you did a survey, the public wouldn't stand behind that."

The city says union demands would cost $35 million — an amount that could force it to raise taxes once again.

The one-day strikes are expected to rotate through each of the city’s districts until March 5.