They built these little curbed islands near the curb on a road I frequent in AA county. There is a bikeable strip of road near the curb and the islands make the travel lane fairly narrow. With a third island in the center of the roadway. I was skeptical but it is astonishing how effective they are at slowing people down. I almost always see brake lights as people approach them. I say almost because occasionally someone approaches at an already reasonable speed and doesn’t need to brake.