As Gatineau's public transit workers prepare to vote on whether or not to invoke their strike mandate, the Canada Industrial Relations Board ruled Monday that transit is not an essential service.

The Société de transport de l'Outaouais (STO) had urged the board to rule transit services must be maintained during peak hours in the event of a strike.

The STO argued that a strike would cause traffic to increase, slowing response time for emergency vehicles "to the extent that the health and safety of the public will be in danger," the decision detailed.

But the board sided with the union, which pointed out that emergency services would be able to use bus lanes to maintain response times in the event of a transit strike.

The union representing public transit workers in Gatineau walked away from labour negotiations with the STO earlier this month after disciplinary measures were imposed on its president, Félix Gendron, and other members of the union.

Members of the Syndicat uni du Transport Local 591 are expected to vote on Wednesday whether or not to go ahead with the strike. The union must give a minimum notice of 72 hours.

In early December 2016, transit workers voted 98 per cent in favour of a strike within 60 days.

The STO is in the process of renewing a collective agreement with 485 drivers and 115 employees responsible for bus maintenance.

​In December 2008, OC Transpo workers went on strike after the Canadian Industrial Relations Board ruled it would not force workers to return to work since transit wasn't deemed an essential service in Ottawa. Transit service was disrupted for two months as the strike stretched on.

Read the Canada Industrial Relations Board decision in the STO case here.