More from Amir’s visit to Japan:

This staircase gives access to the trains at a Tokyo underground station. Given rush hour crowd density, its designers did well to split it in two, to separate the up and down streams of commuters.

Asymmetric Staircase at Ginza underground station, Tokyo

But note how the two sides are of different width. Someone characterized the traffic and found that at peak times more people will be going up than down. Other staircases might have the reverse arrangement, each optimized to its location and usage. These designers took a scarce resource, in this case stairwell width, and allocated it in a totally optimized manner; a very Japanese (and very intelligent) design approach.