Department of Design

April 18th, 2013

Why you almost ran into that jogger, or that biker nearly hit you, the other day

When I’m not walking—and oh, how much I walk!—I run and ride my bike. And weirdly, when I ride or run, people constantly almost run into me. In two different ways, too:

  • When I’m running, walkers either maintain a straight line—straight into me—or, puzzlingly, slowly drift over towards me. If they drift, they start pretty consistently around the 30 foot mark.
  • When I’m biking, people abruptly stop when they notice me, which is way late—about 20 feet away or less, a few seconds before we’re side-by-side.

This sucks, because means our instincts are pretty much the opposite of what we should do:

  • Walkers should stop or shift for runners, who are trying to maintain a pace, and so aren’t as responsive.
  • Walkers should maintain velocity around bikers, who are going faster and so naturally scan further ahead. Bikers gauge their speed and position based on others’ velocity: stopping abruptly when bikers are a few seconds away is what leads to near-collisions.

When I realized the reason for so many near-collisions was that walkers consistently drift into runners and stop suddenly for bikers, I was intrigued; these seem like such different behaviors. But on my runs and bike commutes, I’ve come up with a theory:

Normally, when people walk towards each other, they’ll both make subtle gestural bids on which side they’ll pick *long* before crossing each other. It’s slow and unconscious, a gradual drift one way or the other, naturally responding to the other’s trajectory. (We do this in a much faster way when we run into people in hallways; hence the classic back-and-forth bob, where both people move to the other side at the same time. Hilarious!)

This natural, subconscious conversation is confused when one person is going much faster than the other:

  • For runners versus walkers, the walker’s gradual drift is paced too slowly; they end up directly into the runner’s path rather than adjusting their course in time.
  • For walkers versus bikers, there’s rarely an opportunity for a bid system to occur. Because walkers almost never look before crossing the street unless they hear something, they don’t notice bikes until they’re very close. Instinctively, they stop to gauge the bike’s velocity— and in doing so, ruin the biker’s calculations. If you’ve ever had a close shave with a bike that ‘came out of nowhere,’ this is probably exactly what happened.

Now that I know this, I can plan ahead:

  • When I jog, I make it very clear that I’ve chosen one side or the other as soon as the other person starts to drift.
  • When I’m biking, I assume no pedestrian will notice me until I’m next to them, and always anticipate they’ll stop in their tracks.

On the flip side, when I’m walking, I always move out of the way for joggers, and I try to keep walking at a steady pace if I’m startled by a bike. Cause I know that feel, yo.


  1. krebtacular reblogged this from timoni
  2. aestimo-scribo reblogged this from timoni
  3. ideasdash reblogged this from timoni
  4. nevershittypop reblogged this from timoni
  5. hawkquy reblogged this from timoni
  6. vritrasura reblogged this from timoni
  7. timoni posted this