My fair city/county (Arlington, VA) has got these neat speed bumps that have 2 grooves for bikes to go through. This is a great idea! The one I posted in my pix below is on a downhill, so I especially zoom down this incline.
I don’t think cars can cross the double yellow line in order to bypass these bumps (both wheels over the cut-outs). My neighbor told me that the local cops were ticketing cars that were doing this (I haven’t seen this). Rather, they should let the left wheel take the cut-out and right wheel go over the bump (on their side of the road). Hooray for traffic calming!