Steel is designed to deflect under load, a whole lot more than concrete .. the bridge is doing its job. Sure looks scary, but any engineer will tell you that the deflection is allowable.
The really amazing part that most people don't see .. is how much a long bridge shrinks in the cold, and grows on a real hot day. Many long steel bridges have rollers or hinges one end, to allow for the movement, which can be anywhere between 2 and 8 inches.
Sydney Harbour Bridge spreads and shrinks up to 7 inches, and the arch, rises and falls up to 7 inches, just with heat and cold contractions. I'll wager that Canadian bridge does some sizeable shinking and growing between the depths of a Canadian winter and the heat of a Canadian summer ..