urbanMSP

Because when a three light head with arrows of each color already exists, software is the only change.

In any situation where the signal has a yellow turn arrow and a solid green, you can get by with one less signal by just getting rid of the yellow turn arrow. Do it up this way, I bet this metal sign on this signal pole is a lot cheaper than a sixth signal would have been.
https://maps.google.com/?ll=44.962589,- ... 18,,0,0.75

ohmygosh. just to summarize again:
Flashing yellow left = more options than even a 5 light signal (red/yellow/green/yellow left/green left)
Flashing yellow left = fewer lights = cheaper
Flashing yellow left = easy to implement without redoing existing lights.

Fewer lights than WHAT? What information does a flashing yellow signal convey that a solid green signal doesn't convey?
Having a yellow turn signal is more signals than just not having one, yet it conveys no more information. Nobody's told me I'm wrong about a sold green and flashing yellow arrow having the same meaning, so I'm really not understanding what the point is.

Now you're just messing with us, right?

Is the heat making everybody loopy?

Someone answer the question, what information does a flashing yellow signal convey that isn't conveyed by a solid green bulb?

None.

They convey the same information.

In some situations, the use of one makes more sense than the other.

I'll state it again, it's never been my experience that drivers need to be encouraged to make allowed movements, they have to be discouraged from making not allowed movements. So something that encourages drivers to take left turns that they're gonna take anyway doesn't make much sense to me. And you're always going to have a solid green light, so I'm not sure I understand "better in some situations." It's not an either or. It's "always green light, sometimes an extra light because we think drivers are idiots"

[smacks self for getting sucked into this]

When you have dedicated left turn lanes, there's typically a signal dedicated just to that turn lane. It only has arrows. It doesn't have a green bulb. The people in the turn lane are looking at that signal, not the signal to their right that's directing through traffic. In this situation, the only way to signal to these people that it's OK to turn as long as there's no oncoming traffic is through the flashing yellow arrow.

Now let it go, before you start to look obtuse.

I'll be honest, I don't think I've seen a lot of signal heads dedicated to turn arrows, the ones I can think of off the top of my head have turn arrows and through traffic signals.

But looking at Google Maps, it looks like Hiawatha does indeed have those kinds of signals, so now everything here makes sense.

Also thank you to Mndibile for actually explaining how I was wrong to me rather than just talking past me about how I was wrong.

I'll be honest, I don't think I've seen a lot of signal heads dedicated to turn arrows

Really? That would certainly explain your confusion. I've seen them all over the place.

Drivers being too stupid to understand they have to yield on a green ball is a real problem, to the point that some places arrows have had to be installed because there were too many accidents with drivers not understanding this. If it weren't a problem they wouldn't have spent so much effort developing flashing yellow arrows. (Some places do have a green ball for a dedicated left turn signal, if the movement is permissive only, but these are very rare and are no longer allowed in new installations. American Blvd at the Home Depot is an example.)

In Minnesota, a 3 head signal is not allowed for flashing yellow arrows. There is a national standards for permissive only turns: Flashing Yellow / Solid Yellow Arrow / Solid Red Arrow, but this was yanked from Minnesota standards before it was implemented either. Cheaper just to install a 4 head signal in case a protected phases is needed at some time in the future it could be implemented without hardware changes.

The proposed configuration Solid Green Arrow / Flashing and Solid Yellow Arrow / Red Arrow is absolutely prohibited by federal standards. Solid Green Arrow & Flashing Yellow Arrow / Solid Yellow Arrow / Solid Red Arrow {the bottom section can light either color] is allowed by federal standards but not Minnesota standards. Based on experience it's too hard to tell when a section stops flashing and goes solid and you need to get out of the intersection, so there have to be two segments that can light yellow on the head.

Minneapolis does not use flashing yellow arrows because they're way behind technologically compared to the counties and Mn/DOT. They still have a number of intersections with electromechanical controllers, and a number of intersections lack vehicle sensors, so they'll turn green on a timer whether or not there are any cars actually waiting.

I swear I've seen a flashing yellow on a 3 head signal

I'm also pretty sure that I've seen a flashing yellow on a 3-head signal, but I think a 4-head signal is maybe more common - many of them have popped up on Hennepin County-controlled roads recently. The usual configuration is (I think):

0 <- Solid Red Arrow
0 <- Solid Yellow Arrow
0 <- Solid Green Arrow
0 <- Flashing Yellow Arrow

Michigan uses (or at least did when I was there) a flashing red arrow at the top to indicate a permissive turn. Also, you can turn left on red onto a one-way even if you are on a two-way if there isn't a separately-signaled turn late. The assumption is that if you have a red, so does oncoming traffic. It really works quite well and I wish we had that rule here.

I've seen a lot of 3 section FYA (Flashing Yellow Arrow) Heads in other states, but as I've noted they were yanked almost immediately, probably before any went up, in Minnesota. With the new Mn/DOT signal design manual coming out there will be only two approved configurations for signals over turn lanes, the reason being plastic signal housings are cheap compared to having to pay a crew to modify hardware if they decide the want to change the sequencing. That means there will be some sections that aren't used- in a permissive only the bottom segment won't be used, in a protected only (Like MN 13 in Savage) the second from bottom won't be used.

Dedicated lanes: 4 section vertical
<-- Red
<-- Yellow
<-- Flashing Yellow
<-- Green

Option Lanes: 5 section cluster ("doghouse")
.. O Red
<-- O Flashing Yellow // Yellow
<-- O Green and Yellow // Green

So the pedestrian "improvements" at 38th St. are nearing completion. They took out the refuge islands, making it one LOOOOOOONG crosswalk now. The questionably unnecessary pork chops remain, as wide as ever, forcing pedestrians to zig zag their way across Hiawatha. How can a project that's intent is to improve the pedestrian landscape make things worse?
http://hennepin.s3.amazonaws.com/wp-con ... Street.pdf

I think it's time MnDOT turns Hiawatha back to the city so it can make it more human scale. Rochester did this with US63 and it works well too. Maybe the TH55 designation could just be cut back to 94/Olson, and they could extend 62 to Inver Grove Heights, and the remainder of the route to Hastings can disappear when CSAH42 becomes a TH and the 55 cutoff near the refinery is removed.

I took Hiawatha from the VA to downtown Mpls Friday afternoon at 4pm. So one would think I'm going against prevailing traffic (rush hour). It took a half hour. Some lights I'd have to stop at 3 times while the signal changed. Been awhile since I've had the same type of similar experience on Hiawatha. Horrible. I can drive to Hudson faster.