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Re: [Page Update] Junction Style Guide

PostPosted: Sat Jun 28, 2014 2:14 am
by sketch
I'm beginning to come around to the idea that a single lane drop might merit a wayfinder, especially if there is wayfinder-type signage involved. But I don't believe signage alone should be enough. Take I-75 N exit 208 in Toledo for example: yes, there is a wayfinder sign there, but not a single lane is lost to the exit – the exit (deceleration) lane starts just before the exit. To end up off I-75 you'd have to actively make that lane change right then, with the sign hovering above you; you're not gonna just "oh, another lane, I'll get over" onto it.

DwarfLord wrote:I'm definitely open to situations I may not have considered! 1.5 lanes...that's a new reference to me...does that mean a split where the center lane can go either way? To me that case is handled by the fourth item, signage that suggests a split. If the signage is abundantly clear about one direction being "continue on" and the other being "exit", and only one travel lane is lost, I am not sure a wayfinder is called for based on the lane behavior alone.

That's what I mean by 1.5 lanes both ways, yeah. The MUTCD, by the way, calls that middle lane an "option lane", and calls lanes that are lost "dropped lanes". I like those terms.

The idea is that, if you're in either of the right two lanes in a 1.5-1.5 scenario (1 continue, 1 option, 1 dropped), you have to take some sort of action, or at least make a choice, to stay on the road. In the dropped lane, you must get over; in the option lane, you must be sure to stay to the left. If you're a chronic speed limit obeyer and you've been in that right lane for quite a while, the reminder would be good. The wayfinder rules kind of assume that you might have forgotten exactly which highway you're on and that you could use a little nudge.

Like I said, I'm starting to think that there are some situations where maybe a WF is warranted even if a single lane is dropped. This one here is definitely warranted — it's (1 continue, 1 option, 1 dropped), but pan up just a little bit and you'll see that the dropped lane was one of only two lanes of I-475, and that the continue lane actually just came off a left entrance ramp. Apparently, it's a pretty dangerous interchange because of that. I think we have a few options: (1) if there's a legit dropped lane that'd been there a while, (2) if there's a dropped lane and ≤2 continuing lanes, (3) if there's a dropped lane and a wayfinder-type sign, or maybe some combination of them.

Thanks, yes I had been interpreting the term "wayfinder" to refer to any situation where extra guidance for continuing on the same road is helpful. In San Jose for example we have a ramp that goes on for nearly two miles with two sub-exits of its own! But if the term is not to be used for anything other than controlled-access MH and F types that would be good for me to be clear about. In that case, what if anything do we call continuing-path guidance in other situations?
Ramp-ramp splits are covered below in their own section. The section on naming addresses navigation instructions. Ramp types will always give instructions if the names are different, so the type complications and display considerations are not in play there. It's much less complex – if the name of the s-in matches the name of one s-out, the s-out won't get a prompt. This includes "no name". It could maybe be explained better, but it's there.

Re: [Page Update] Junction Style Guide

PostPosted: Sat Jun 28, 2014 5:28 am
by sketch
DwarfLord wrote:Good stuff. I am thinking we need to be clarify some terms before we can craft the best language.

The term "dropped lane" is good, but does it mean a dropped travel lane -- i.e., a lane that, for some distance before approaching the intersection, was neither signed nor striped as an exit lane? Or does it include lanes that were never anything but an exit lane? For example, is the right-hand lane of this segment considered a "dropped lane" when it departs for Hwy 150 to Ojai? The right-hand lane joins at the start of the segment and continues over half a mile before it exits for Hwy 150, but it is striped as an exit for that entire length.

The term "wayfinder-type signage" -- would it include a BGS with arrows straight down, or no arrows at all, over the continuing lanes, regardless of what neighboring exit signage looked like? To be sure I am not advocating that "wayfinder-type signage" by that definition would warrant a wayfinder! My thinking is that only signage and striping that suggests a split, or that is absent, unclear, or inconsistent would be sufficient to warrant a wayfinder based on signage alone. In fact, by this criterion, the absence of "wayfinder-type signage" would warrant a wayfinder much more than its presence.

Right, dropped lane needs to be defined. It would have to be a lane that exists besides as an exit lane, indeed. A lane that starts by virtue of a directly previous entrance ramp may also not qualify.

Whether the arrows are straight down or pointing left/right depends on physical geometry (this according to the MUTCD). With arrows, I consider it a "wayfinder-type sign". Without arrows, usually it's just a reminder. At least, that's my experience.

Details do need to be hammered out further, but I wanted to get that out of the way while I had the chance just now. I'd like to look at a bunch more examples and consider how the variations would apply to them.

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Re: [Page Update] Junction Style Guide

PostPosted: Mon Jul 14, 2014 9:14 pm
by sketch
I believe guidance should be added to the Intersections page on median U turn segments that aren't part of an MUTI. These segments are currently set as "street" type as a matter of course, which I believe is fine, since they are used pretty much exclusively to get to a destination or from a start point at the end or beginning, respectively, of a route. We concluded as such during the MUTI discussion.

Perhaps more common in certain areas than in others, these are ubiquitous in both New Orleans and Detroit, so I have a lot of experience with them. In New Orleans, we name these segments "U turn", since they are almost always signed as such. In other places, I have seen these either unnamed or name "Turnaround", as that appears to be the general name for them elsewhere. I do not believe that we should use a different name in different places, but maybe we should consider whether it's wise to at least name them all something.

We also set the geometry here such that the instruction is "turn left" onto the segment. Whether or not there is another such instruction at the other end of the segment depends on the actual geometry – when it's straight across, we have a second instruction, but where there's a substantial curve leading traffic onto the next road, we do not. I believe in Michigan they include the second instruction always, because their turnarounds tend to be much more gently curved at the ends, and are mostly straight. I think it'd be wise to include some guidance about this as well.

Re: [Page Update] Junction Style Guide

PostPosted: Mon Jul 14, 2014 10:18 pm
by sketch
I will say, though, that "as a matter of course" is not universal regarding current use of the street type, as I've seen a number of these set to the "service road" type (which is of course wrong), and some set using the AGC rules (same as the road), which I think is excessive and unnecessary.

Re: [Page Update] Junction Style Guide

PostPosted: Wed Jul 16, 2014 5:11 am
by sketch
kentsmith9 wrote:
CBenson wrote:It can be disconcerting to have the next instruction be for an exit a couple of states away and 10 hours away.

I have always agreed this is a problem. This is where the freaking "continue" instruction that ALL the other navigation systems provide has us beat. Such a simple instruction. Hopefully we can fix that with Junction Boxes! :mrgreen:

Not sure if I've lost the context, but the faraway instruction is "Continue straight for x hours to Exit 123..."

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Re: [Page Update] Junction Style Guide

PostPosted: Wed Jul 16, 2014 5:42 pm
by sketch
PesachZ wrote:
sketch wrote:
  1. Add a control city, if it is known.
  2. Remove the compass cardinal from the stub name.
  3. Add a space after the stub name.
  4. Create a freeway-type stub just before the junction with no street name.
While these have already been added to the wiki along with a note to use option #4 as a last resort only because it can prevent turn delay speed averages for routing, I discovered there be another good option as well.

You can make the segment after the split be no-name, even the lead in segment and the segment after the no-name stub share identical names and road types.

I tested an example with no alt names and it works fine (audio below), there is also a live working example with alt names in Connecticut. When seeing this up especially if it will be a long no-name segment instead of a stub, on a MH or Fwy, care should be taken with alt names to ensure working detour prevention.

TTS audio to the no-name Fwy stub

EDIT: Added PLs

I really don't know why I didn't think of this. In light of this information, I suggest we replace the entire list with this method. There's no need to fiddle around when we can get the right instruction with minimal "hacking".

Re: [Page Update] Junction Style Guide

PostPosted: Wed Jul 16, 2014 6:04 pm
by sketch
PesachZ wrote:I think we can document the order of preference should be to name the two wayfinder segments to:
1) Match the BGS provided it is different than the lead-in segment name (s-in)
2) Be no-name.

Although we still need to test what happens when both the lead in segment and the wayfinder segment are no-name.

True – if the lead-in segment and wayfinder segment are both no-name, there will be no instruction. So that can't work. That'd only be an issue in complex wayfinder situations, but it's definitely worth considering.

Hopefully, we should be able to use (1) most of the time, and in every Interstate example I've seen so far this has been adequate, I think. (1) should be the default, and shouldn't include too much qualifying information. (2) should be the alternative method only for the times that (1) doesn't work. For that reason, I don't think presenting it as a list is the best way to go, as it makes it look like there are options. I think it would work better in-text.

[Page Update] Junction Style Guide

PostPosted: Thu Jul 17, 2014 5:54 am
by sketch
PesachZ wrote:I agree that a stub will fix it, but only if the next segment after the stub is named. If it is needed to be unnamed, we will stool have the problem and an additional issue. Making it a no-name stub followed by a no-name segment might flag and be 'fixed' by any of several scripts. Without editors understanding the need for it, they might think it was unnecessary. Understanding the theory, and putting an alt name on the portion after the stub will prevent the node from being considered extra, and fix detour prevention.

The point of the stub is to get an unnamed segment in there. If the out segment is unnamed anyway, there's no need for an unnamed stub.

Detour prevention only operates to prevent "detours" of two segments or more.

I don't know that an alt name will prevent deletion of a node when both segments' properties are otherwise the same. Of course, this is easy to test.

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Re: [Page Update] Junction Style Guide

PostPosted: Wed Jul 23, 2014 1:10 am
by sketch
KB_Steveo wrote:And the drive through lots section, needs to be changed to say 3 segments. (maybe with a picture of that too.)

It depends on the drive-thru. Some have a single entrance and exit point, but most in my experience have one entrance and one exit, so the drive-thru is not a loop in itself, but creates a loop with the road it's on. Compare the westernmost of these three drive-thrus with the center and easternmost (ignoring any short internal segments and side-road connections for purposes of this argument).

In other words, look at these selected segments only. If those were the only mapped segments of each of these drive-thrus, the central and eastern ones would need only two segments each, whereas the western one would actually need four – three for the loop and one to connect the loop to the road.

Re: [Page Update] Junction Style Guide

PostPosted: Thu Jul 24, 2014 9:40 pm
by sketch ... structions

This subpage recommends 22° as the angle for creating a "stay" or "exit" instruction – I don't agree with this, and it doesn't agree with the Interchanges subpage. My recommendation is to keep the angle around 10-15° – it allows for smoother transitions; also, we aren't trying to avoid the endpoints of the range, we're trying to avoid the transition point around 44°, so the shallower the better (within reason).

Also, I think the language "stick with" should be replaced with, maybe, "stay near" – no need to use doglegs on an 80° turn, for example.