I don't know how motorists would react, but it's funny to see how most of them react to speed bumps and speed humps.
On a few streets with parks, etc., we have a few long speed humps – the kind that are quite manageable at the 30 km/h speed limit, or even at 40 km/h. Yet most motorists tend to slow down to a crawl, and quite often they brake right on them, which means their suspension springs even more than if they were travelling it at full speed. But the ironic aspect is that those same people who drive over those humps at 10-15 km/h will drive on much more severe potholes at full speed!
So maybe these humps would be effective after all.