The flashing yellow arrow has a very informative section on this Wikipedia page: https://en.wikipedia.org/wiki/Traffic-light_signalling_and_operation including this information: "The flashing yellow arrow is now a standard configuration for protected/permissive turn signals in the new US 2009 Manual on Uniform Traffic Control Devices, released on December 16, 2009. " This document is over 8 years old but Sunnyvale has not adopted this standard configuration on any new lights installed since this time. Traffic has increased dramatically in Sunnyvale since the 2009 MUTCD was released
Other comments on the above referenced Wikipedia page that are directly applicable to the Innovate Climate Action initiative: "The purpose of these signals is to allow traffic signal controllers to safely select movements as needed to maximize traffic flows, and to prevent vehicles from stacking up in left turn pockets to the point that they block through lanes of traffic. It also gives traffic engineers more flexibility with the leading and lagging protected left turn phase configurations, allowing for better progression (coordination) between signals. This saves gasoline by stopping fewer vehicles. "
Here is a pdf link to the most up-to-date version of the MUTCD: https://mutcd.fhwa.dot.gov/pdfs/2009r1r2/mutcd2009r1r2edition.pdf Discussion pertaining to flashing yellow left turn arrows begins on Page 465 in Section 4D.17 Signal Indications for Left-Turn Movements
No, not flashing red arrow. Yes, flashing yellow arrow. If there is no oncoming traffic, there is no need to stop, just to proceed with caution. Here's a link to a good description of how it is employed in Nevada: https://www.nevadadot.com/safety/roadway-safety-improvements/flashing-yellow-arrow-turn-signal The flashing yellow arrow is already commonplace in many other states in addition to Nevada, I have personally experienced it in Oregon, Utah, and Colorado. According to Wikipedia, "The flashing yellow arrow is now a standard configuration for protected/permissive turn signals in the new US 2009 Manual on Uniform Traffic Control Devices, released on December 16, 2009." With this document released over 8 years ago, why has Sunnyvale not adopted this standard configuration on any new signal lights that have been installed since that time?