Zero chance that crossing gates wouldn't slow vehicle travel through the areas where these would be added.
I'm not opposed to making commuting less desirable via car, but this isn't really how I like to do it. The line wasn't designed with crossing gates in mind.
Exploring the legality of a bylaw for conflicting with the train is fine, adding red light cams at all of these locations is probably better, plus cameras would double as a revenue generator from drivers.
Travelling is a right, but driving is a luxury, and if the road owner (the city) wants to do certain things to protect transit infrastructure, I'm all for it.