Signal control sometimes gets it right, with traffic clearing the junction in the green time allowed. But more often, some traffic is caught at red, or the lights change just as traffic arrives. Traffic includes pedestrian as well as motor traffic.
With signal control, road capacity is restricted as traffic is held up when nothing is happening on the junction.
Signals cause stop-start traffic, conflicting speeds and consecutive queueing. Self-control on junctions with equal or no priority allows simultaneous filtering at low speeds. Which is more efficient?
Congestion forms at traffic lights like iron filings cluster at the poles of a magnet.
Signal control blocks flow and prevents infinite dispersal or escape opportunities. It imprisons us. Self-control frees us to go on opportunity. It allows the milk of human kindness and cooperation to flow uninterrupted.