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Traffic Q&A: What’s the deal with the flashing yellow arrows?

Post by John Henrikson / The News Tribune on Dec. 17, 2010 at 5:07 pm with 5 Comments »
March 11, 2011 5:12 pm

Question: Robert Staeger of Vancouver is curious about a new type of traffic signal he’s encountered.

“Recently I observed in the Hillsboro, Ore., area left-turn arrow signals changing to flashing amber after a short period (apparently allowing for the initial wave of oncoming traffic to pass through). This seems like a good idea to me. Is this a new idea? Is it done in Washington State?”

Answer: The flashing yellow left-turn arrows have started to appear nationally in recent years. The new left turn signals have four phases: green (protected turn), solid yellow (prepare to stop), red (stop) and flashing yellow, which permits a left turn, but only after yielding to pedestrians and oncoming traffic (which has a green light). Trial studies showed that the lights were effective in reducing motorist confusion and traffic accidents, while improving traffic flow.

Oregon localities, including Washington County west of Portland, were among the first to embrace the new signals. And they’ve spread to several Washington locations, including Kitsap County, Everett, Bellevue, Kennewick and Vancouver.

Federal Way piloted its first yellow flashing yellow arrow signals in 2006, shortly after federal and state authorities begin allowing them under an interim rule, according to Rick Perez, the city’s traffic engineer. The city just turned on its ninth last week and had plans to install more in the next year.

A comparison of accidents before and after the conversions showed an overall improvement in safety in Federal Way. “Like most traffic changes, initially there was some negative comments, but those have died away, and now we mostly get requests for more of them,” Perez said.

Expect to see more flashing yellow arrows in the wake the Federal Highway Administration’s full approval last year.

“I’m excited about the benefits being realized, and hope that more agencies jump on this bandwagon,” Perez said.

Here’s a link to a cool animation of the signal.

Got a question about traffic congestion, construction, spending or other transportation issues? E-mail it to Traffic Q&A. Include your name, hometown and daytime telephone number. We’ll answer as many as we can.

Leave a comment Comments → 5
  1. I know about the left on a red arrow on one-ways. Can you give us some examples? I know 13th and A Street in Downtown is an easy one. It gets a little iffy with the onramps. From my understanding 38th Street eastbound to I-5 North/16 is another ok free left turn because the offramp is not right next to it at the intersection of 38th.

    Oh and I like the blinking yellow left turn in Vancouver. They have been doing that for at least 10 years.

  2. vikefan66 says:

    I appreciate that the new lights are reducing accidents. What bothers me is that we needed to spend the money to implement a new device to even further simplify a process that wasn’t particularly convoluted in the first place.

  3. why do we have to yield to pedestrians

  4. I can appreciate the flashing yellow arrow. It works will in Federal Way.

    Vikefan66, you might want to take a look at how they work in Federal Way. Take a drive to 1st way South and S 336th street.

    I don’t think they were meant to reduce accidents. They do improve traffic flow where their installation is appropriate.

  5. Whoops! I see Federal Way says they improve safety. I don’t see how, but if they say it’s so, then I guess it is.

    They do improve traffic flow. I can vouch for that.

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