Montague street bridge

From my understanding, this bridge keeps getting hit and people keep seeming to consider things like raising bridge or lowering road, but what I don’t understand is why can’t they put a series of sped humps to slow down vehicles to about 20 km/h so that people have more time to realise that their vehicle is too tall and abandon their attempt, and even if they do hit the bridge its at a much lower speed which would surely be better than the current situation because it would at least be less likely for vehicles to get wedged under the bridge.

just put the bumps where the 40 km/h sign is…

If someone here who knows how road engineering regulations are set up in Australia is something like this not allowed, I notice that in Australia speed bumps/humps seem to be incredibly uncommon when they are such a simple solution that would surely help with traffic calming on especially troublesome main roads and busy streets.