The curb is a hazard to cyclists, more so than a crash with inattentive pedestrians. The majority of Dutch cycle lanes are level with the sidewalk and how often do you hear of accidents (not caused by mopeds)?
That is considered “level” - pedestrians will wander into it anyway (mostly tourists) since there is no perceivable barrier unless there is enough traffic.
It may be worth noting that there are so many bicycles in Dutch cities that, as a pedestrian, you learn very quickly that you have to be every bit as aware of them (if not more so) than you are of cars. It's mostly a pretty different situation that the occasional bike bombing down an unseparated lane on a sidewalk.
It can work OK when you have wide paths that have lots of different types of users on them. It's less good when you have fairly narrow sidewalks.
not if the curb is sloped (american suburbs tend to have these), so that you could ride up (or down) it in a pinch.
i'd support such a little "mound curb" separating cars and bikes at the same grade, which would likely be less expensive to install than building 3 different grades for cars, bikes/scooters, and pedestrians (which i'd also support).
