> There's no way that's true, is it? What circumstances would a four way stop sign allow for more traffic flow than a roundabout?
Heavy traffic. In most situations a roundabout will do better, but when completely saturated, the 4-way has a slight advantage. This is probably due to how 4-way stops with dense traffic develop an predictable alternation pattern that eliminates ambiguity and reduces the clearance requirements.
What I've seen here is that traffic will sometimes back up into the roundabout from a blockage down the road, and then things grind to a complete halt, which a 4-way stop should never suffer from.
Heavy traffic. In most situations a roundabout will do better, but when completely saturated, the 4-way has a slight advantage. This is probably due to how 4-way stops with dense traffic develop an predictable alternation pattern that eliminates ambiguity and reduces the clearance requirements.