Traffic Talk: Is Oklahoma City going to get permissive about left turns?
Don Gammill: “An interesting question,” says Oklahoma City traffic engineer Stuart Chai. “There are new standards for permissive (yielding) left turns at signalized intersections that vary depending on roadway conditions.”
Here's a question about turning:
I thought I heard the city was getting new signals that had turn-left-on-green yield. They would be catching up with the rest of the large cities. I have driven in every major city, from east to west and north to south. I would like to hear from you.
Here's the expert on that one, Smokey.
“An interesting question,” says Oklahoma City traffic engineer Stuart Chai. “There are new standards for permissive (yielding) left turns at signalized intersections that vary depending on roadway conditions
“Generally, if there's a dedicated left turn lane, the current standard is to use a flashing yellow arrow. If the arm on the traffic signal is just long enough to reach to the edge of the separate lane from which left turns are made, it is possible under such circumstances to use a five-section left turn head with an R10-12 sign (the ‘left turn yield on green' followed by an illustration of a green circle (representing a green ‘ball' indication.).
“Here is a link to where you can find this discussed in the Manual on Uniform Traffic Control Devices (MUTCD), 2009 Edition, with Revisions 1 and 2. Note, however, that the left turn yield on flashing arrow sign that Oklahoma City and some other cities are using is not in the manual. The manual is silent on them at this time. This is covered in Section 4D.20 (http://mutcd.fhwa.dot.gov/htm/2009r1r2/part4/part4d.htm).
“There are many instances of traffic signals set up with signals and signs for permissive left turns in Oklahoma City that have been out there for many years. It is not a new practice but it is also not one that can be used everywhere either. It is used with discretion bearing safety in mind.