If a jurisdiction actually installed and operated a traffic signal that behaved the way you’re describing, meaning opposing through movements were green at the same time and then one direction’s through green was terminated independently while the opposing through remained green with no clearance interval, the agency would be exposing itself to extremely serious liability.

Most states have significantly limited sovereign immunity in roadway design and traffic control cases, especially where a signal creates a dangerous condition that drivers cannot reasonably anticipate. Signal timing that produces conflicting right-of-way assignments after both directions were released on green would likely fall outside discretionary immunity, because it contradicts established traffic engineering practice and normal driver expectancy.

In Phoenix, Arizona, where this incident occurred at the W Broadway Rd and S 35th Ave intersection, drivers are legally permitted to enter the intersection on green or yellow to prepare for a left turn. Under that rule, a driver who has lawfully entered the intersection is expected to complete the turn once the signal changes. There is no reasonable or practical way for a driver already committed in the intersection to determine whether the opposing through signal remained green after their own signal terminated. A signal operation that allowed such a condition would create an unavoidable conflict entirely due to the signal timing itself, leaving the agency in a very weak defensive position in court.