There are way
too many bad assumptions in the analysis.
Speed bumps are designed to make drivers to slow down.
Not all speed bumps are. Some are designed to make car drivers slow down, while allowing larger vehicles to pass over them unmolested. The intention is that large emergency vehicles which have a wider track, such as fire engines, shouldn't have to slow down, while cars with a narrower track, do. Still others are designed to ensure drivers are travelling at or slower than a particular speed, but not necessarily
slow them down.
Going over a typical speed bump at 5 miles per hour results in a gentle bounce, while hitting one at 20 delivers a sizable jolt.
Not so, either by design (see below) or by accident. There are two speed humps in particular that I can call to mind that are perfectly fine for driving over at the speed limit of 25 mph. Different makes of car show the same response. I see other drivers choosing
not to slow down too, so it's not just me.
If you hit a larger speed bump—like a speed hump or speed table—your car might not fare so well.
A speed table
is one of the type I mentioned above: they are designed to deliver an uncomfortable bounce at, say, 35 mph, while traveling over them at 25 mph is perfectly fine.
This is nothing at all to do with size. In my experience, it's the smaller speed bumps, and back in the UK, "sleeping policemen", that deliver the most uncomfortable jolt, even at very low speeds, with unconcealed tyre traps at parking lot exits being the most uncomfortable of all, at any speed. The approach and departure angle determine how much horizontal energy is converted to vertical motion, not
There's also the horrible assumption throughout that we're talking about a "typical sedan". Even though I read the US motor press almost daily, I still think of sedan chairs when I see that word. The answer there is "What speed bump, commoner?" But what about an emergency vehicle? These have provision for poor road conditions. What about a luxury car or an SUV? These aren't always as great as they're sold to be, but some like the Land Cruiser and Range Rover definitely are. Unimog or other military vehicle? Baja, rallycross, or rally car? These are all designed to go over rough terrain at speed. What about a hovercraft?