[rhizome]

Isn't variance in flow rate the crux of the issue? Merge lanes are a special case in traffic, where another flow is entering the channel. This creates turbulence around the merge point that does not exist where there is pure laminar flow and all lanes can be treated equally. Would it help if "simple cure" was renamed as a "simple improvement?"

[Arelius]

This.

Sure, there exists a point where the input flow is great enough that traffic must move slower. OP's entire argument is based off of this. The problem is that there are many things you can do to slow down the flow rate even further, and merging poorly creates this "turbulence" which wastes further flow.

And, it's clear that no improvement in merging behavior can beat the maximum road occupancy, however we can approach that limit much more closely.

I think that conceptually modelling traffic as fluid flows is quite clever, and the "turbulence" idea is particularly satisfying.