Road Types (USA) – comprehensive overhaul of drivable roads

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A freeway can certainly end or begin at another type road, and many do. I thought of adding that a few days ago, but I wasn't near a computer.

As for mid-freeway connections to major/minor highways, this is possible as well, especially at the beginning/end of a concurrency (say, when US-11 and I-59 run together for a time). This will be covered by this section of the Interchanges JSG, which is pending a rewrite. That's still a type of interchange, though. Interchanges may use non-ramp segments if they are freeway/highway splits, mostly to achieve visual continuity on the map, but the point is that it's an interchange and not an intersection.

If there's another type of junction you're concerned with, I'd like to know.

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Most of what I have to say has already been said well, in Brian's response. I will add a little bit. Also, very interesting to hear about the separate classifications by certain AZ towns/cities. I wonder, are these FHWA-approved?

Anyway, your proposal sounds good. This sounds like something that would be carried out on a state-by-state basis; correct me if I'm wrong.

What conclude (for now) by looking in AZ to see what they did I see two things I will try to describe more in a bit:

(1) Phoenix, a rather large city, is comprised of a bunch of Minor Highways and Major Highways. This seems odd at first. It seems biased toward having Major Highways every half mile or every mile or so. Take a look. It seems highly differentiated.

(2) Rural areas of AZ currently seem biased to be less highways and more primary streets and streets. So the major arterial between distant cities can be primary streets. It seems under-differentiated.

So, does this make sense?

What Brian said was right, that the US/SR system augments FC in rural areas to temper this. I write simply to add that the FHWA's FC guidelines themselves mention that principal arterial (MH) spacing is expected to change a lot between rural areas (rather sparsely distributed), metropolitan areas (one every mile or two), and city centers (up to one every 1/8 mile).

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I think the point is we just need to add wording to support some of these other conditions that are missing from the Wiki.

Sketch, do you want to take a first shot at it? Or let me know and I am happy to modify that section to describe these other conditions.

Done. https://wiki.waze.com/wiki/Road_types/USA#Freeway

When a concurrency diverges I'm not sure we can really get away with not using ramps simply because there's usually a need for pathfinders, at least until we get that new feature.

There are ramp segments, only very short ones (stubs). This is covered in the rewrite of the wayfinder rules. So yeah, there are still Ramps per se, but a casual observer would not see them.

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I highly doubt waze is going to divert you 40 miles to stay on higher classified roads if that specific primary road cuts 40 miles off your trip.

This sounds like a testable assumption.

Actually I can answer that now — Waze will not use that Primary Street.

The resolution level (i.e., the distance from the beginning and end of a route at which a type is penalized) for Primary Street is 15 km for shorter routes and 50 km for longer routes (over 200 mi by air). 50 km is still less than 40 miles.

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As for US-191 (for example).... If anyone might need to use that road for a long route, they should be able to do so. Using a Primary Street for this route means it's unlikely they will be able to. Users traveling along highways out west should be able to navigate along them. A competitor's GPS would do the same. Users making those drives should be prudent enough to know that they shouldn't wait until their tank gets to E to fill up, anyway.

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US highways are set to Major in the national standard for a reason — mostly, for rural long-distance routing.

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Maybe so, but since a US highway is a Major Highway under the rules, it wouldn't happen now. (If it's been implemented there.)

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Fredo-p, your interpretation of how functional classification works is incorrect.

The standards are set by the FHWA. They are federal standards. "Principal arterial" is defined by the FHWA, as are all the other functional classes. The standards are national, so the Waze rules based on them are national.

"The process of determining the correct functional classification of a particular roadway is as much art as it is science." (emphasis added)

You are reading this sentence wrong. Fitting a particular roadway (in Arizona or in any state) into the correct functional class (defined federally) is "as much art as it is science" because the federal classes overlap somewhat and are not rigidly defined. So a state is at some liberty to make some borderline roads principal arterial and others minor arterial, and so forth — but that does not mean that one state's "principal arterial" is another state's "minor arterial", or anything like that. The FHWA still has to approve every state's FC maps.

(Yes, there are a lot of Major Highways in cities. Good. That's how it works.)

FC is a national system. The guidance is national guidance. The FC portion of the guidance is not subject to changes by the states.

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Ignoring US and state highways when implementing the new road type system is a mistake. The US highway system is also a national system, and it was taken into account when creating the national standards. Setting US highways to Major Highway is, likewise, not subject to change by the states.

The state highway systems are not nationally set, so maybe some rules pertaining to the road types of state highways may be changed by a particular state. But, at a minimum, "primary" state highways should be at least Minor Highway — every state has state highways, you can decide which of those are "primary" (easier in some states than others). But you'll get better results in most cases by leaving state highways as mH at least.

Props on implementing FC in Arizona, but if my understanding is correct, then you have not implemented the new road type rules. You will have problems routing through rural areas.

The difference between what AZ has implemented and what everyone else is doing is that AZ is strictly adhering to FC while all other states are using the FC + the "hybrid" guidelines to help preserve continuity and reduce "pruning" for longer distances (state highway is mH minimum and US highway is MH minimum regardless of FC). Is that a fair summary, or are we missing something?

This is my understanding of the situation.

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Oh — please don't get me wrong, I'm very impressed with y'all's work implementing FC throughout Arizona so quickly. I told as much to nnote a few days ago. Of course, the good stuff tends to get lost or forgotten when a problem is identified.

I only send PMs when I need to get someone's attention or when I need to keep something private. If there's already a thread on the topic I'll typically just post there. My feedback might be useful to more than just one person.

It is comforting to know that this was a simple miscommunication and not a deliberate attempt to make such a huge change to the system.

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Hah, and here I thought that leaving the highway systems out was the "experiment" part.

Luckily it should be easy to fix; since you already did all the FC stuff, just find a good highway system map and/or route descriptions and bump up the types for those.

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Okay,
I really, really hope this helps resolve some of the issues that have happened as a result of the very strict and "simple" table I have created. This is the new table I have made. What I did was remove only the road types that are not recognized in Arizona. I have also relabeled the classifications to how the Arizona DOT has labeled them.

Is this a more usable table that follows what is on the road types wiki?

The attachment new table.jpg is no longer available

Not sure if you have an updated table somewhere, but this chart is non-compliant.

This is a hack job, but this is the correct content for your simplified chart.

new table.png

(218.14 KiB) Downloaded 877 times

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The only thing that should change from one state to the next is the way that state handles its own state highway system (and possibly county routes). By default, all state highways are mH or higher. Some states which have both primary and secondary state highways may wish to demote the secondary state highways into the "State Hwy BUS, SPUR[a], LOOP" column. Some states don't have county routes at all; some states have "county highways" and "county roads" and may wish to make the former mH+ and the latter just Street+.

But the bulk of the guidance remains the same — nothing major changes in FC, except that some states might just use the "Other Freeway" class (as opposed to "Other Freeways and Expressways"), thereby placing all partially-limited-access 'expressways' into the "Other Principal Arterial" class. Michigan does this, for example. That doesn't actually change any FC rule, it simply makes the distinction easier for us in that state. Also, the guidance as to US highways remains the same.

So it isn't really necessary for all 50 states to supplement the FC guidance, as some will not need to change any of the state highway rules at all. If anything, making a state chart should only involve renaming some column headers to match that state's maps and maybe removing a column or row or two if they don't apply. For example, Michigan does not have "Other Expressway", and calls the next two classes "Other Principal Arterial" and "Minor Arterial"; Louisiana has "Freeways/Expressways" and "Principal Arterial" and "Minor Arterial", and "Parish Roads" (not county routes), no Interstate business routes, no CONN or ALT (I think) state highways, and so forth.