Visit Amsterdam and that is exactly what you will see. In Amsterdam when you step up off the car roadway onto the pedestrian/cycle sidewalk, the first 6 or so feet are the bicycle lane. Be careful not to stop there (thinking you are in the clear just because you are no longer in the roadway) - you are standing in the bike lane. Take a couple more steps to be in/on the pedestrian portion of the sidewalk, safe from bikes and cars. To help peds see this, the bike lane portion of the sidewalk is red brick or other reddish brown material. In Denver and Boulder it seems they're tending ot use green as a color/signifier, but you get the idea.