Speed and proximity. They are the two factors that lead to both pedestrian anxiety about and actual bike v. pedestrian conflict. If you are walking and a bike whizzes right by your shoulder, it's disconcerting and unpleasant. A person on foot is highly maneuverable (no momentum) and may dart left or right or stop suddenly without warning. So, there is a high risk of a bad outcome.
People on bikes are bigger than pedestrians -- bike plus biker plus gear -- and less forgiving. And, bikes are faster. Keep in mind that the squared variable in mv2 is v, velocity. So, bikes have a special obligation to watch out for and take care of pedestrians when sharing the road (as in crosswalks) or shared paths.
I've been thinking about this a lot recently because, as previously noted, I've been riding the paths along the Charles River to accommodate camp drop-off for Princess NS&S. (I really did get stung, I didn't really give up the bucolic route!) I'm following two simple rules that I encourage others to follow:
- Give a wide berth when passing a pedestrian, particularly from behind
- If you can't give a wide berth, slow to just faster than the person you're passing
What's a wide berth? Depends on the speed, but at least three feet and ideally five feels right.
What about yelling "On the right/left"? If you need to warn the person you're passing that you're passing, you're going too fast or coming too close. Plus, in my experience, yelling something just heightens the risk that the person will do something unpredictable. (Does he want me to move left? Is he coming on my left?) And, it's just downright annoying.
When I'm riding in traffic and a driver honks just to warn me that he's behind me, it's aggravating. I'm in traffic. I know cars are going to pass, I don't need to be reminded. And, if it's a dangerous situation, slow down until you have room to pass slowly. I feel the same way as a pedestrian among bikers. Get by me safely ... and silently ... or cool your jets.
Finally, the anxiety and risk created by a high speed differential between bikers and pedestrians makes most shared paths a lousy place for faster riders. We should stick to the streets or just take our time.