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Protective Permissive Traffic Signals



Left Turn Signals

There are two types of left turn signals in operation at City intersections: “protected” and “protected/permissive”.  Many drivers often ask questions, and express confusion, regarding the operation of the protected/permissive left turn signals.

Protected Left Turn Signals

Drivers have been accustomed to seeing left turn signals where there is initially a green arrow, followed by a yellow arrow, followed by a red arrow.  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 red arrow, left turns are not permitted.  These types of left turn signals are called “protected” left turn signals. They can be helpful, but when there is no traffic, they can cause unnecessary delays.

Protective/ Permissive Left Turn Signals

In the last couple of years, a five-section left turn signal has been implemented at intersections in the City.  Under this new arrangement, left turn signals provide the usual green arrow, followed by the usual yellow arrow.  After the yellow arrow has terminated, motorist are faced with a solid green ball signal (no red arrow).  During the display of the solid green ball, left turns can be made when there are adequate gaps in opposing traffic to complete left turns safely.  This type of left turn phasing is designed to help minimize delays by eliminating the need for the red arrow and allowing vehicles to turn on the green ball when opposing traffic is cleared.  By not having the red arrow, motorists do not have to sit and wait to turn left even when there is no opposing traffic, a situation that often occurs during periods of low traffic volumes.  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 red arrow.

Advantages of Protected/Protected/Permissive Left Turn Signals

Reduce delays, as left turn drivers may have an opportunity to make their left turns during the green interval.

Allows the use of a shorter time cycle length by reducing the time of the fully protected green interval for the left turn movement.

Less chances of disturbing traffic in the adjacent lane, since cars waiting in the left turn lane are less likely to exceed the length of the turn lane.

Current Protective/Permissive Intersections

“M” st @ Loughborough/Collins

“M” st @ 23rd St.

“M” st @ 21st St.

“M” st @ 19th St.

“M” st @ 18th St.

“G” st @ Childs Ave

“G” st @ 21st St.

“G” st @ Main St.

             
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