Left Turn Signals
At a few locations in Plano, drivers are accustomed to seeing left turn signals where there is initially a green arrow followed by a yellow arrow, 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 yellow 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 yellow 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 protective / 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 protective / 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.
Flashing Yellow Arrow
The flashing yellow arrow is now mandated as the replacement indication for the circular green (green ball) in a protected/permitted left turn signal head. The permissive green in a left turn signal means that the left turning vehicle must yield to oncoming traffic but may turn left in gaps when safe to do so. This is currently displayed as a green ball, but in all future signals the circular green will be replaced with a flashing yellow arrow. For more details on how this works, view our brochure.
Double Red Arrow
At many locations where the City uses protected only left turns, the need for traffic to stop when needed is emphasize by using two red circular indications or two red arrows. The presence of two left turn arrows does not mean there are two left turn lanes; motorists should look at signs and pavement markings to determine which lane(s) are for left –turning vehicles. Several studies suggest motorist compliance with red indications is higher with the red arrows than the circular red indications. Plano will begin using the double red arrow indications on all newly replaced signal heads for protected only left turns.