Traffic lights

[Scott5114]

Norman appears committed to the five-light doghouse signal. They're everywhere.

Haven't seen a FYA in Oklahoma at all yet.

[froggie]

On the subject of Flashing Yellow Arrows, I've noticed recently that Andrews AFB has a temporary Flashing Yellow RIGHT Arrow at an intersection, due to construction.

Not the first one in the region, though...there's a Flashing Yellow Right Arrow on Virginia Ave NW near the Watergate (yes, that Watergate).

Several Flashing Yellow Left Arrows in Alexandria, mainly along Duke St (VA 236), but also one on Washington St (VA 400/Hidden VA 90005).

[SidS1045]

I don't know how the city of Boston screens its traffic engineers, but they must not require any sort of expertise, because this city is the worst I've ever seen.  It's usually not an issue of not having traffic signals where they're needed, but the city is at least 50 years behind the times in installing pavement sensors to trigger the signals.  Every day on my commute I deal with at least half a dozen signals which turn red for the main road with no traffic whatsover waiting on the side street.  Operating traffic signals on timers in that situation is so 1960.

[Chris]

Those are static traffic lights, they do the same cycle over and over again. They may be time programmed, but are fairly insufficient these days.

[agentsteel53]

I don't know how the city of Boston screens its traffic engineers, but they must not require any sort of expertise, because this city is the worst I've ever seen.  It's usually not an issue of not having traffic signals where they're needed, but the city is at least 50 years behind the times in installing pavement sensors to trigger the signals.  Every day on my commute I deal with at least half a dozen signals which turn red for the main road with no traffic whatsover waiting on the side street.  Operating traffic signals on timers in that situation is so 1960.

if you don't run 3 red lights each way on your commute, you're not truly driving in Boston!

[deathtopumpkins]

I've noticed that problem around here too, but the lights seem to be affected by traffic levels, so I assume that there is some sort of sensor. Many entrances to now-dead shopping centers that are like this seem to change periodically just to go through the cycle. Nonexistent cross-traffic only has a green for a few seconds, while through traffic has it for several minutes.

As for flashing yellow arrows, I noticed a few of them on US-158 on the Outer Banks installed this summer, and might have a pic lying around somewhere.
What do you do on a yellow arrow? Yield to oncoming traffic when turning?

[Tarkus]

What do you do on a yellow arrow? Yield to oncoming traffic when turning?

Yes, that's it exactly.  The flashing yellow arrow means the same thing as a doghouse with a green light but no green arrow.

-Alex (Tarkus)

[burgess87]

That'd better be in the new MUTCD & some updated driving manuals, because that's gonna confuse a lot of people.

[mightyace]

That'd better be in the new MUTCD & some updated driving manuals, because that's gonna confuse a lot of people.

Given how much most people actually read these days, it will confuse a lot of people even if it's in the MUTCD and updated driving manuals. 

[roadfro]

That'd better be in the new MUTCD & some updated driving manuals, because that's gonna confuse a lot of people.

The meaning of a flashing yellow indication is already in the MUTCD Section 4D.04

Standard:
The following meanings shall be given to highway traffic signal indications for vehicles and pedestrians:
(...)
D. Flashing signal indications shall have the following meanings:
   1. Flashing yellow–When a yellow lens is illuminated with rapid intermittent flashes, vehicular traffic is permitted to proceed through the intersection or past such signal indication only with caution.
   (...)
   3. Flashing RED ARROW and flashing YELLOW ARROW signal indications have the same meaning as the corresponding flashing circular signal indication, except that they apply only to vehicular traffic intending to make the movement indicated by the arrow.

However, the meaning of a flashing yellow arrow as it relates to turns is not fully made clear from these definitions--especially as it relates to yielding to oncoming traffic or pedestrians. The current definition of circular green does a better job

Standard:
The following meanings shall be given to highway traffic signal indications for vehicles and pedestrians:
(...)
A. Steady green signal indications shall have the following meanings:
   1. Traffic, except pedestrians, facing a CIRCULAR GREEN signal indication is permitted to proceed straight through or turn right or left except as such movement is modified by lane-use signs, turn prohibition signs, lane markings, or roadway design. But vehicular traffic, including vehicles turning right or left, shall yield the right-of-way to other vehicles, and to pedestrians lawfully within the intersection or an adjacent crosswalk, at the time such signal indication is exhibited.

It should be noted that the new version of the MUTCD has a proposed text revision that aligns the meaning of a flashing yellow arrow to that of the yield-when-turning condition of the circular green.

[Tarkus]

It's also shown in the 2007 MUTCD Figures Notice of Proposed Amendments, as Figure 4D-12.

ODOT's also got them codified in their "Traffic Signal Policy and Guidelines" document--see Figure E1 (page 63 of the PDF).  If you'll scroll down, you'll notice that Figure E2 (the "doghouse") comes with the warning "Not acceptable for new designs on state highways".  (Farther up in the document, they say that there are limited exceptions, but it's pretty clear they're "gung ho" on Flashing Yellows.)

The 2007-2009 Oregon Drivers' Manual also describes Flashing Yellow lights on the section about protected/permitted signals (pages 22-23), but the illustration of a protected/permitted signal that they show is of a doghouse.  I presume they'll be fixing that in the 2010 edition--especially since there's 188 of them in operation as of August 6th, 2009.

-Alex (Tarkus)