I live and bike in Cambridge. We have separated bike lanes in some places, but pedestrians generally don't respect them in my experience. I used to think pedestrians that walked in designated bike lanes just didn't know it was a bike lane. But the lane on Vassar Street has a bike icon every 30 ft or so and is a different color than the rest of the sidewalk. Yet pedestrians still seem to prefer it to "their" sidewalk just to the left or right. Same thing on the Southwest Corridor, which has designated bike and pedestrian lanes, which are not respected ignored by pedestrians at all when I've been on them. If they are going to ticket cyclists, it seems only fair to start ticketing pedestrians walking in the bike lane too.