The maintenance employees of the STM approved a six-day strike mandate on Sunday, while the union remains hopeful it will reach an agreement with the transit network.
Union president Gleason Frenette says the 2,400 workers he represents are particularly worried about the disappearance of work-family balance measures.
The maintenance workers, mechanics, electricians, plumbers and carpenters on-hand on Sunday voted 98 per cent in favor of the walkout at a general meeting, with a participation rate that the union described as "unrivaled."
The six days are banked to be used if and when the union decides.
After more than 30 meetings, negotiations are ongoing and the union hopes that this strike mandate will result in a "change of tone."
Frenette challenged the STM has never been so "aggressive" in their requests.
The STM wants to impose mandatory overtime, Frenette said, even though maintenance employees completed almost 500,000 overtime hours last year.
"We do not understand, all our employees are dedicated," he said in a telephone interview with The Canadian Press. "Five hundred thousand hours is huge. It's been increasing year by year for more than 20 years."