No worries! I don't know if pollute is the word I would choose, as it again seems a bit strong and negative (imagine if you were a new mapper and someone says that adding a perfectly true elevation you saw on a sign during your hike to the database was polluting OSM!). So I don't even think the last sentence is necessary, but I understand where you're coming from.

PS As a consumer of elevations, you might be interested in this RFC (not by me) for a proposal to formally allow elevations in feet, if the unit is specified, following similar conventions for maxspeed=* and maxheight=*: https://community.openstreetmap.org/t/rfc-documenting-feet-as-an-an-optional-elevation-unit/108543

Hello,
Thanks for going through these mistagged elevations (I'm guessing you're prompted in part by https://community.openstreetmap.org/t/announcement-openlandcovermap/108392?). I agree that this and others that you're editing are almost certainly unit errors where the ele=* tag contains feet rather than meters.

Just as a gentle suggestion, would you mind rephrasing your changeset comment? It's understandable that US mappers, especially newer ones, wouldn't know that ele=* has to be in meters, rather than the elevation in feet that are universally used and often signposted on the peaks themselves in the United States. Calling such cases "feet vandalism" comes off as a bit aggressive and negative, because it implies, at least in my reading, that the original mappers were not acting in good faith. Perhaps something more like "Converting elevations that appear to be in feet into meters per OSM standard tagging" or something would more accommodating?

Again, I have no problem with these edits, it's just a suggestion on how the changeset comment tone comes across to Americans. Feel free to disregard.

Best,
Will

Hi again. There's no way Avalon is reasonably highway=primary in OSM. I drove down it a couple months ago, it's one through lane in each direction with extensive crossings and bike lanes. It's a much less major thoroughfare than nearby primaries like Central, and even maybe other nearby secondaries. If the Caltrans database is telling you to upgrade roads like this to primary, then the database is not a good fit for bulk import into OSM.

I noticed that despite my comments on changeset/145714639 inviting you to discuss these massive changes in how roads are tagged in the LA area, you have not responded and instead have proceeded to continue editing based on functional classifications. I was hoping to have a cordial discussion, but at this point I feel I need to escalate this to the DWG and ask them to revert these undiscussed mass edits until a consensus can be reached. Other users on OSMUS Slack agreed with me on this action.

Hope to continue discussing road classification principles in Los Angeles.

Best,
Will

PS if you can't tell, I've been thinking about OSM road classifications for a while, so forgive me for my hot takes/strident opinions. I actually wrote up a whole diary entry on what I learned from my efforts to reclassify roads in LA (some of which you've now reverted) here: @willkmis/diary/399345. Hopefully, you might find it useful, at the very least as insight into how I view things. I actually specifically mentioned FCs there as well.

Hi,
Happy new year to you as well! Thanks for the additional information, and for including the citations on your changesets that I've seen in the last few days. I am familiar with the Caltrans map you linked to, having referenced it extensively when drafting the CA trunk classification guidelines (osm.wiki/California/2022_Highway_Classification_Guidelines).

Unfortunately, I strongly disagree with your approach of standardizing OSM tags to Caltrans functional classifications, because I think doing so makes OSM a less useful and consistent map. The problem is that OSM's highway=* tag definitions and goals do not align well with state-level functional classifications, in my opinion and in that of the cohort of mappers across CA and the US that put together the osm.wiki/United_States/2021_Highway_Classification_Guidance, (see the exact line there: "However, it is not a good idea to try to establish a 1:1 correspondence between OSM classifications and the state functional classifications. This will result in over-classification, with a high number of primary and secondary roads, and there will often be primary and secondary stubs and dead-ends. States generally do not put much thought or effort into their functional classification maps, especially in smaller towns, where the classifications are often arbitrary and do not always reflect reality.") I agree with that assessment within LA: even in the changes you've already implemented, there are a number of strange primary stubs with no corresponding change in road attributes, such as Figueroa, Grand, and Topanga Canyon, that in my view clearly show the dataset is at best an additional tool in helping to determine classification, not the be-all end-all.

Moreover, I don't think that Caltrans FCs correspond very naturally in a one-to-one way with OSM's highway=* values. "Other Principal Arterial", which you seem to be conflating with highway=primary, in particular appears to me to contain too wide a variety of roads. At the very least, such a correspondence needs to be discussed (either on the community forum or the OSMUS Slack, which hosts a very active discussion on highway classification that I'd be happy to add you to) and documented on the wiki before being implemented. I'm happy to dig into the cases of individual roads and consider their specific context, but that's my view of the general approach here.

Perhaps more philosophically, I disagree with your claim that "The idea is to have uniformity across all mappers. There is no better way to achieve that – instead of having mappers make their own judgment." OSM's goal is to utilize local knowledge to the utmost to map the world, and I don't think we need to defer to a statewide agency that doesn't really care whether Hollywood is an "Other Principal Arterial" or "Minor Arterial", whereas I, someone who lives here, can tell you that through traffic going from, e.g. the Chinese Theatre to Silver Lake would avoid it and take Sunset or SM Blvd instead due to the road's characteristics (high pedestrian volume, frequent signals, narrowness), and that OSM should reflect that.

Lastly, I'm open to discussing the trunk classifications of PCH, though the talk page of osm.wiki/California/2022_Highway_Classification_Guidelines might be better suited for it than here. But I do want to point out that trunk is most certainly not only "for a true expressway and behaves similarly to a freeway" in the current consensus of US mappers, as described in osm.wiki/United_States/2021_Highway_Classification_Guidance. It can be used for that in "areas of high population density" (though note there is a different tag, expressway=yes, that can better portray the same concept), but in general highway=trunk can also be used for "the most important non-motorway roads that provide principal, long-haul connections between population centers of regional importance". I tagged PCH as trunk through Malibu because in my opinion it fit that definition as being the best way to get from Santa Monica to Oxnard, and the southern portion because it's the best way between Long Beach, Huntington Beach, and Newport Beach. I don't see houses along the road as contradicting that definition, just as they don't for US 101 through San Francisco, for US 395 through Bishop, or countless other examples throughout the country. Other road attributes, like lane counts, speed limits, and "expressway-ness", are already covered by other OSM tags, whereas highway=* is the only one that expresses the road's important in the broader network.

Looking forward to discussing this further!

All the best,
Will

Hi Kate,
Thanks for responding. I started a thread on the OSMUS Slack asking for opinions on this change: https://osmus.slack.com/archives/C2VJAJCS0/p1703005593240569. The consensus among US mappers in that forum agreed with your assessment that lanes=2 is OK in this situation if paired with lane_markings=no, also agreeing with the guidance you pointed out on the wiki. In light of that, I drop my opposition to you adding lanes=2 to roads similar to this, but ask that in future similar changes you add lane_markings=no as well to more explicitly characterize the situation.

As an aside, at least in this area, the department of transportation tends to add such markings all at once, or at least within a couple weeks of eachother. Given the imagery is more than a year old at this point, I doubt lane dividers will be added in the future.

Happy mapping and happy new year,
Will

Hi! It looks like you're making quite a large number of road classification changes across the LA area over the past couple days. Some of them seem perfectly fine to me (like upgrading Beverly Glen to secondary, or a lot of the various tertiary edits). But I don't agree with this change upgrading Hollywood Boulevard to primary, nor with a few other of your choices (like having Sunset primary through Sunset Strip, having Exposition primary at all, or having Gayley secondary in Westwood). Road classifications are certainly never exact, and I sometimes go off "gut feel", but given the extent of your edits, would you mind explaining what rationale you're using to make these major changes to the status quo? How are you picking what should be primary, secondary, etc?

Additionally, I (and anyone else who might come across these changesets presumably) would greatly appreciate if you could use more descriptive changeset comments in the future, so for instance "Upgraded Hollywood Blvd to primary based on such-and-such reasoning" would be much more helpful than just "Primary Road".

Thanks!
Will

Hi, what source are you using to find that this road has two lanes? I just removed the lanes=* value because based on a survey there were no lane markings at all, which appears to be corroborated by the latest aerials (Bing) and Streetside.

Best,
Will

Well, maybe Stony Island instead of Jeffrey: it's wider and gets exits from the Skyway and I-94. I guess that reinforces both the point that road classification is hard but also that the categories it attempts to represent are real. If you're interested, I actually wrote a whole diary post about the heuristics I came up with to decide urban road classification, although it was mostly put into practice in my current home of Los Angeles, much of which is of course a very different built environment than Chicago: @willkmis/diary/399345.

Sure, I agree that it's complicated. I don't think there's any single criterion you can use to separate primary from secondary in all cases. Fundamentally, the road classes represent a spectrum of importance, so at some point, judgment calls will have to be made. All I'm saying is that the current way Chicago is mapped does not in my view accurately represent the spectrum of road hierarchy, and I'd argue the policy of only upgrading state/US routes, while unambiguous, is a fairly arbitrary rule that doesn't correspond to much in reality. The multitude of other mappers that have come in and tried to change the primary tagging seems to support my opinion, but given that I don't live in Chicago anymore I'm not going to go in and start an edit war or anything. Just wanted to provide some feedback.

Re: the roads mentioned so far, honestly, at least Ohio/Ontario, Ida Wells, Columbus, Michigan at least north of Roosevelt or so, Roosevelt, Jeffrey, Ashland, and Western all seem like part of a reasonable primary network to me, in line with how most other US cities are mapped. That set is far from all of the secondary roads in the city.

No worries! Yeah that section is debatable, and it's gone back and forth in the past. Note that the part between La Tijera and Imperial is tagged with expressway=yes (see expressway=*), which is designed for situations where the road is built up to higher speed standards regardless of classification.

Hi, it looks like in this change you've upgraded PCH entirely to trunk between Venice and Dana Point. Can you describe your rationale for this change? In my experience, PCH acts essentially as a primary road in these areas, given that through traffic just gets on the 405 to go any significant distance.

In case you're not aware, highway=trunk tagging has been the point of some controversy in OSM. To address this, the California mapping community has come up with statewide guidelines for the trunk network, emphasizing connectivity and the "best" routes between major destinations. You can find the guidelines and their rationale here: osm.wiki/California/2022_Highway_Classification_Guidelines. As part of that, the tagging for CA 1 in the LA area was agreed to be as it was previously, as trunk only between CA 22 and CA 55 in Orange County. The guidelines are always subject to change, so if you'd like to advocate for your tagging, it might be nice to drop a post on the Discussion page on the wiki before making major changes. Let me know what you think!

Best,
Will

Hi Flierfy,
I see you've edited the 10 to be access=no due to the recent damage to the freeway. While it is true on the ground at this moment, I am not sure this change to OSM data is a good idea.

Recent news reports suggest the closure will only be for 3-5 weeks. The wiki only suggests tagging a road closure if the road will be closed >6 months: highway=construction. Since many data users only pull data every once in a while, that means the change could propagate for much longer than the road is actually closed. If this road closure is marked at all, then it should probably be a conditional restriction with an end date. Otherwise I think there’s a big risk that it’ll screw up routing on an important road segment for a really long time. I commented a similar note on changeset/143980941, which was then reverted.

Let me know what you think.

Will

I commented this on the OSMUS Slack, but I do not think this edit is a good idea. The wiki only suggests tagging a road closure if the road will be closed >6 months: highway=construction. Since many data users only pull data every once in a while, that means the change could propagate for much longer than the road is actually closed. I don’t feel comfortable changing this freeway to access=no at least until an expected timeline is announced, and even then it should probably be a conditional restriction with an end date. Otherwise I think there’s a big risk that it’ll screw up routing for a really long time

I modified the wiki in this change to reflect this discussion: osm.wiki/w/index.php?title=California%2F2022_Highway_Classification_Guidelines&type=revision&diff=2613176&oldid=2501813.

Happy mapping!
Will

And I'm not sure I buy your argument about the state/US routes. North appears to have the same number of lanes and roughly the same frequency of signals as lots of other roads in the area that it looks like you've downgraded from primary to secondary in the past, like Ashland, Western, or Roosevelt. Is there any material difference between those roads and North Ave besides the state route designation?

Ok, I'm not sure I agree, but probably at least Ida B. Wells and Columbus should be primary then? They come directly off the freeways.

Hi, just wanted to comment that I'm visiting Chicago, and as a former resident, I was pretty surprised that Michigan wasn't highway=primary. I've seen that you've led some discussion on the wiki and whatnot, and that there's not necessarily consensus. But I will say that Michigan and Ida Wells definitely "feel" like primary roads to me, based on how similar roads are tagged in other places. Moreover, just going by what's a state/US route feels a bit arbitrary to me, and I don't think it leads to a particularly useful map IMO. The Chicago classification looks a little too "flattened" to me, there's definitely more of a natural hierarchy to the road network than is implied by everything in the central area except North Ave. being a secondary.

Just my two cents, but let me know what you think.

Will

Hi,
Do you have a source for changing this bike path name to match the train line? I've only ever seen it signed/referred to as the "Expo Bike Path", even with the new train line letters being in place for a few months now. This is probably because the bike path still mostly parallels Exposition Blvd., even if the train is not the Expo line anymore. I think this should remain matching existing signage (or maybe expanding the abbreviation to "Exposition Bike Path") unless you have evidence it's been officially changed somewhere.

Best,
Will

Hey,
Thanks. I'm still not sure if Reedley or the NPs are significant enough to warrant a trunk connections, since no other towns of 25k population or National Parks in CA are classified as such. If they are, it seems like the trunk classification should extend all the way to the destination, not just dead end where the construction quality decreases, as the goal is to move away from an entirely road construction-based classification. But on the other hand, given that the freeway is a stub anyway, it's not the most egregious outlier in terms of network connectivity anyway, and I am inclined to defer to your local judgment. So if you'd really rather it stay trunk, we can document that as a case for the urban gray area on the wiki.

Best,
Will