The idea was if you had conveyor belts next to each other, with a low speed difference, you could get up to high speeds on foot somewhat safely.
If the red belt goes six kilometers per hour, people who can walk could step onto it without too much risk. The yellow belt would be double the speed, at 12 KPH, but that’s only a six KPH step for someone already on the red belt. And so on up to (in the image version) 36 KPH for the indigo or whatever that far left color is.
The facility in the image is probably for testing only. In a fully finished version, it would ramp up to the middlemost lane, and then ramp down on the far side, palindrome-style. And there would be another set, going the reverse direction, on one side or the other, allowing for bidirectional transport.
It takes a bit of imagination (or a better illustrator than myself) to really consider what it would be like. Airports often have those moving sidewalks, but they are single-speed. They do speed you up, but imagine if they had those next to each other like this?
I imagine that 36 KPH is about as fast as you’d want to go, even next to two 30 KPH lanes, as things like windspeed (though partially avoided by having the tunnel-like colorful forcefield thingies) would get annoying.
I’m sure it’s not at all practical, but I still like the imagined version all the same.