Road Types (USA) – comprehensive overhaul of drivable roads

[davielde]

What's wrong with davielde's sheet?

Nothing, I suppose. If people are comfortable working off of the spreadsheet, that's fine. My only concern was the number of "anonymous users" appearing in the revision history versus the actual names for the wiki. I just changed it so that everyone can edit instead of just comment. I initially pieced together the links based on the first things that I came across through searching, so the better links for certain states or the interactive/non-interactive split mentioned in earlier posts can be updated by anyone now.

[davielde]

After the Georgia data is transcribed, someone needs to tell the spreadsheet owner to delete it so we don't have two competing, unsynchronized, data sources.

The owner is following this thread.

[davielde]

Consider best ways to ensure roadway consistency across state lines. That is, some segments of road going from one state to another may have to bend to the other state's rules for some distance to help ensure good inter-state routing.

I've been taking notes as I've upgraded Michigan's southern border with Ohio and now Indiana. I'm curious to eventually have more information on how things match up between different states nationwide. For now, I've been following the road type guidance without bending anything just so it will be easier to see variations once everything has been upgraded along the borders. I'm completely fine with leaving things "as is", but I also did not want to lose sight of vectorspace's comment here with everything else going on in this thread. If we do bend another state's rules, I also wouldn't want to keep track of a list of numerous exceptions. That defeats the purpose of attempting to move to a more objective system with the new road type guidance.

For the most part, where I have seen the largest number of discrepancies at the border is not from strict FC, but in applying the "hybrid" rule that has state highways minimally at mH. Obviously, US highways benefit from the minimum MH rule, so those would be consistent. There are a few situations like this though where I think we could benefit from eventual discussion. In this example, Indiana "State Rd 120" (collector auto-upgraded to mH) continues as Michigan "Territorial Rd" (collector/PS) for about three miles before intersecting with Michigan's "Edon Rd" and Ohio's "State Rte 49" (both minor arterials/mH). Do we perhaps make an exception to upgrade Territorial to mH to avoid pruning for longer distances? Do we make an exception to downgrade State Rd 120 (legitimately a collector anyway) to PS back to either the city of Fremont or the junction with I-80? Do we simply leave everything as is even though it means State Rd 120 to Edon Rd may be pruned initially? The goal of this example is not to obtain an answer in this one case, but rather help set some parameters on if or how far we may be willing to "bend" without having to manage a large number of individual exceptions for each state.

[davielde]

So a US highway should be a major highway regardless of FC?

Not exactly. It would be a major highway minimum, but if FC has it as a freeway, keep it as a freeway.

If FC has it as a minor arterial (or less if that ever happens), it would always be upgraded to major highway under the new rules.

[davielde]

Just to clarify, this isn't an experiment and it is, in no way, focused at optimizing the cites. All of the changes we made are in direct reflection of the Arizona DOT FC map (which is current as I have been in direct contact with ADOT). There is no way this should ever be called an experiment.

?

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?

[davielde]

FWIW, US-51 in N Mississippi has several stretches where it is classified as a primary collector. It parallels I-55 for most of its length.

The goal of the automatic upgrade to MH minimum for US routes was to have a consistent "resolution" level, which is the pruning concept discussed elsewhere as part of the FC rollout. A US route collector (actually any collector) classified as a Primary Street segment will not be considered apart from the first or last 15km of a short route or 50km for a longer route. Major Highways do not have that limitation, and they help better reflect the "network" that makes up the US highway system. The upgrade to MH doesn't mean that Waze would prefer the collector portions of US-51 over another potentially faster road, but it would at least consider them for longer routes.

Unless as a collector it routes someone through a fire swamp or is filled with rodents of unusual size, it sounds like it may be a good bypass for I-55 if someone has "avoid highways" (freeways) enabled. Waze would be more willing to use it for longer distance travel or detours as a MH if it's deemed faster than any other route. Keeping it as PS may end up routing such a user way out of the way even if US-51 otherwise would be part of a fastest or shortest non-freeway route.

Perhaps we need to get a basic section on "pruning" added to the wiki as well. That may help clear up some confusion as to where road types actually do matter from a routing perspective.

[dbraughlr]

I would like to see the rationale documented for the exception for ramps to be used for at-grade connectors.

[dbraughlr]

I favor the use of functional classification. But I see a possible deficiency.

I believe that primary street should be used for the main road linking two rural towns (and presumably thus the main street through the town) when no higher classification applies (which is often the case). This could well require local knowledge of the editor rather than a published document. Functionally the street is the primary route even though there isn't much traffic.

A primary designation is very relative to population and traffic densities.

[dbraughlr]

I would like to see the rationale documented for the exception for ramps to be used for at-grade connectors.

The exception for at grade connectors is in the Wiki here http://wiki.waze.com/wiki/At-Grade_Connectors#Exceptions.

-- Except that when this was posted, in that article there was not even mention of the new situations (in which to use a ramp for an AGC) listed in sketch's draft article (the subject of this thread).

I believe that dbraughlr may be referencing the bit about jughandles and Michigan lefts specifically.

Which is correct. Those were the only situations mentioned in sketch's draft. But there was no link at the time I asked from sketch's draft page to any rationale in the wiki or even in a forum thread.

Later:

Sketch, in this section it appears it would be good to add more in explaining why the Jug handles and MI left, in addition to the turn lanes, should use the ramp type. Perhaps we can link to the more detailed article that I have already updated here and include the Jug Handles and MI left to this page as part of the explanation.

This sounds like a suggestion that someone should document the rationale for the new situations in which an exception applies for a ramp as an AGC.


<Edited to explain time warp.>

[dbraughlr]

I routinely downgrade Minor Collector from Primary to 4x4 / Dirt Roads if they are not paved. This is the only way for the Avoid Dirt Roads option to work.

I am on the side that believes where our streets and minor highways are dirt, they can't be avoided anyway and should be set according to function so that they work correctly for the people who haven't set "Avoid dirt roads" (whatever that is really supposed to mean). The function of a road and its surface material are independent characteristics. Not all 4x4 trails are dirt. Abandoned paved highways can be 4x4 trails.