Study the sign shown. When is this MUTCD advance-warning device required on an approach?
When the primary traffic signal lacks sufficient approach visibility✓Correct answer
Before an abrupt two-lane narrowing that restricts simultaneous passage
At the nearest access point to a nearby public parking facility
One mile and/or two miles before a freeway rest area
Explanation
It is required when the primary traffic signal is not visible for a sufficient response distance. The sign gives advance warning; it does not replace the signal or create a new signal phase.
