Floor vibration: how fast do people walk in buildings?
Update (March 2017): how fast do people really walk in real buildings? We produced a video to illustrate different walker speeds in important settings like laboratories, hospitals, and offices. Of course, some people walk faster or slower, but you might be surprised at where the centers of those distributions fall.
I've written recently about how to look at footfall vibrations created by people walking around in sensitive buildings like labs or hospitals. The theme of that post was that all sorts of the parameters and variables we care about are distributions rather than singular numbers.
One of these is the walker speed, expressed in paces-per-minute (ppm). We're interested in walker speed because floor vibration response scales strongly with walker speed. In that earlier post, I suggested that these walker speed distributions might look conceptually like this:
Building occupants naturally walk faster or slower depending on setting. Clearly, people walk faster in corridors than in small rooms. Within those two categories, however, there is still some distribution.
Of course, I didn’t put any numbers on those distributions. So, what are some realistic walker speeds?
Everyone seems to have his or her own ideas, and that’s a problem for design or evaluation of vibration-sensitive settings like labs. Footfall vibration impacts scale dramatically – nonlinearly – with walker speed, so it’s important to get it right.
The standards don’t do a good job of clarifying this. The widely-used VC Curve system (discussed in IEST-RP-CC024 and IEST-RP-CC012) provides limits for different uses, but is silent on how fast people actually walk. AISC DG-11 discusses limits and also includes a calculation methodology, so walker speed and weight are part of the conversation. But DG-11 seems to suggest that “slow” walkers inside rooms move as slowly as 50 paces-per-minute. This seems unrealistic to me: download a metronome app, set it to 50 beats-per-minute, and try to walk around with the beat.
People naturally walk faster in corridors than they do in small rooms, so it makes sense to acknowledge this fact in the structural vibration design. However, it seems like the "50/75/100ppm" regime for “slow/medium/fast walkers” as suggested in DG-11 can sometimes lead to anti-conservative floor structures.
If we take a statistical-distributional view of walker speeds and vibration impacts, it appears unlikely that any realistic lab or clinical space would house occupants walking on average only 50ppm. [Update (March 2017): here's where that walker speed video might come in handy.]
Byron has been measuring people walking around in buildings for nearly 20 years. Contact him if you’re worried about floor vibrations in your building, whether it’s a laboratory, office, or medical center.