Would a better solution to be having bike lanes as part of the sidewalk vs part of the vehicle traffic? Move the side walks out a foot 1/2 on each side, partition off the bike lane with a small curb (could be even smaller than now is on the roads, because a person veering into the bike lane isn't as dangerous as a car into bikes or vice versa) and you reduce the walking space a bit. I noticed the older lanes in Amsterdam were mostly like this. Sometimes there was a small fence-like divider between the sidewalk and the bike lane. Sometimes you get people walking on the bike lane and I'm sure cyclists get annoyed by it, but a simple bell ring makes you move. And it's a lot easier to move yourself than it is to move your car or your bike.
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