Left Turn Signals

How are Advance Arrows Implemented?

Advance arrow phases are developed for intersections on a case by case basis, and must meet the needed requirements. These advance phases are either omitted or added depending on the impact they have on opposing traffic flow.

Where are Left Turn Signals Installed?

Left turn signals are usually installed:

• At intersections where oncoming traffic is constant
• Where obstructions make it difficult for the driver to see oncoming traffic

Why do they only Come on at Certain Times?

The left turn advance for most intersections is activated all day, and must have 3 cars for the signal to be activated.; Few intersections may have the left turn advance omitted due to volumes at that time of day, therefore this phase is omitted to provide extra time to the through phase. However in a non-coordinated "free" mode the controller is permitted to cycle through all the phases that have demand.

For example: An entrance into a commuter lot may require advance left turn phasing in the morning, yet the rest of the day it simply isn't necessary and would negatively impact the opposing traffic. This arrow however would be permitted at night if the demand were present because the opposing traffic volumes are significantly lighter.

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