The science of male restroom design

The following are some scientific observations I've made regarding male public restrooms.

On the psychological side of things, simply from naturalistic observation while using a restroom myself, two males will hardly, if ever, use urinals directly adjacent to one another. If there is no other urinal available except one adjacent to another one that is currently in use, the normal "polite" thing to do is to use a toilet stall, or wait until someone finishes at the urinals. If one enters an empty restroom, one will also usually take the urinal with the least chance of having someone use the adjacent urinal. In the case of a row of urinals, this would be the one at either end--there's only one urinal adjacent to it. Otherwise, most will take the next best one.

So, if there are 3 urinals, only 2 will be used (the ones on each end). If there are 4 urinals, only 2 will be used (the ones on each end). If there are 5, 3 will be used (the ones at each end, and the one in the center). If there are 6, only 3 will be used (the ones at each end, and then one of the 4 between them. Any remaining urinals will be adjacent to one that is in use).

So, for optimal cost/usage, it is best to have an odd number of urinals, and the best that can be hoped for is that if the designer intends for nurinals to be available, then they will have to install 2n-1 urinals.

A way around this is to put a divider wall between each urinal. In my opinion this is much cheaper, and allows for n urinals to be used if n are installed.