Both sides of a Canadian National railroad labor dispute toughened their stances on Wednesday.

According to media reports, United Transportation Union workers began staging off-and-on strikes at various facilities.

Meanwhile, the railroad began locking-out union members.

The actions come after the rank-and-file UTU members overwhelmingly rejected a tentative contract agreement.

If the dispute drags out, it would affect not only rail shipments but also intermodal truck shipments.