At a few locations in Plano, drivers are accustomed to seeing left turn signals where a green arrow followed by an yellow arrow is followed by a circular red. On the green arrow, drivers are given the right of way to complete left turns free of any other traffic conflicts. The amber arrow warns drivers that the left turn signal is ending. On the circular red, left turns are not permitted. These types of arrows are helpful; but when there is no opposing traffic, they can cause unnecessary delays.

Protective/Permissive Left Turn Signals

At many locations in the City, a different type of left turn signal has been implemented. Left turn signals provide the usual green arrow which is usually followed by the normal yellow arrow; but after the amber arrow has terminated, drivers are now faced with a circular green signal. During the display of the circular green signal, left turns can be made when there are adequate gaps in opposing traffic to complete the turn safely. This helps minimize delay by allowing vehicles to turn after opposing traffic has cleared. By not having the circular red, motorists do not have to sit and wait to turn left when there is no opposing traffic. The signal still provides a green left turn arrow during rush hours when traffic is heavy; but during off-peak hours, left turning vehicles are not delayed by a circular red.

Why doesn't the City use Protective/Permissive Left Turn Signals everywhere?

The City uses protective/permissive left turn signals at locations where drivers can turn left safely into adequate gaps in approaching traffic and drivers can clearly see oncoming vehicles. Examples of protected/permissive left turn installations include Park Boulevard at Custer Road, Park Boulevard at Independence Parkway, Parker Road at Independence Parkway, Parker Road at Custer Road, K Avenue at Park Boulevard, and many others. If a location does not use protected/permissive left turn arrows, it is because an engineering study has shown that the intersection will operate more safely with protected only operation.

Why does the Left Turn Arrow come up at the beginning of green at some locations and at the end of green at others?

At some locations, the green arrow may come up before or at the same time as the circular green signal. At others, the left turn arrow may be displayed after the circular green indication has been on for a minute or so. In order to provide good signal coordination, special left turn sequencing is used to provide smooth traffic flow through many intersections in the City. On many streets in the City, including intersections on Coit Road, Plano Parkway, Park Boulevard, and Parker Road, one arrow comes up at the end of the green. In some cases the operation varies by time of day to accommodate changing traffic flow patterns.