Proposal talk:Highway=quaternary

4 major road classes is enough, if you use highway=trunk

In the rationale, it is said that "In the United States at least, classifications typically take the following shape: Secondary for state routes, tertiary for a few major county routes, and unclassified for anything less than that." - But this is ignoring highway=trunk and highway=primary. If you look at how the tags are used in England, where they were developed, highway=trunk could be used for all major roads which are not freeways/motorways (e.g. US Highways in the Eastern half of the USA), highway=primary for State highways, highway=secondary for county highways, highway=tertiary for minor through routes, and highway=unclassified / residential is for very minor roads. The problem only comes from not using highway=trunk as a class of road, so State highways are demoted to secondary, when they should be highway=primary - they are usually the main long-distance road in the area. --Jeisenbe (talk) 09:18, 5 April 2020 (UTC)

I could agree with such a system being used, though I have a few reservations about adding U.S. Highways all as trunk routes, and state highways as primary, if implemented strictly. This system, while adhering to official classifications, could lead to some issues:

• US Highway 52 near Williamson, WV - This section of US-52 is basically a residential street but would end up listed as a trunk route.

• Ohio State Route 15 near Findlay, OH - This, due to it being a state route and not a completely controlled-access motorway, would flip between motorway and primary (or be entirely assigned as primary) between Findlay and Carey. The problem is that the trunk road, US-23, splits off at Carey and proceeds north, as an at-grade two-lane roadway effectively paralleling I-75, while OH-15 jumps over and connects to I-75 to complete the Columbus-Toledo highway link. I would think that adhering to the classification standard here would end up confusing drivers, as drivers would anticipate that US-23 would be the more well-upgraded and faster route north to Toledo, while that is not in fact the case.

I'm not entirely certain the English system is perfectly applicable here for other reasons as well - for instance, the British roadway system would appear to be a more top-down roadway system (see [1]), while the modern U.S. road system, with the exception of the Interstates, largely was developed bottom-up (many states had their own state highway systems starting in the 1910s, but the U.S. Highway system wasn't created until 1926). As each state used its own criteria to determine how they would develop their state highway systems, they differ (and sometimes massively so) in scope (for instance, look how many primary highways there would be in this part of Kentucky: [2]).

Again, I'm not entirely opposed to the idea - but, without the addition of quaternary routes, I believe there would need to be some key differences for the U.S.'s situation:

• highway=motorway would need to be applied not just to all freeways in the U.S., but all expressways as well.
• highway=trunk would be applied to all other roads on the National Highway System. This would allow only the non-expressway U.S. Highways that connect particularly important areas to be set as Trunk, so the tag isn't diluted heavily by sections that, for instance, parallel Interstates.
• highway=primary would be applied to roads that connect 2 or more county seats, regardless of if they are U.S. routes, state routes, or county routes, by the following criteria:
  • 1.) If a U.S. or state highway connects the two county seats on a relatively direct course (not veering away from a straight line between the two points by more than one-third of the distance between the two points), that route should be chosen. However, if a combination of state and U.S. highways produces a more direct line of travel, this should be used instead.
  • 2.) If a route following the above criteria is unavailable, the route with historical precedent (i.e. the route that is shown as the main road between the two points on an 1800s map, for instance), should be chosen. If no such route existed either, then no such primary route should be added. If such a route did, however, exist, then it should be thoroughly checked for pavement status, designations, lane count, etc., and only be added with all of that data.

(Note: The reason for this is that there are situations, such as US-6's routing in northeastern Ohio/northwestern Pennsylvania, where the official "main road" flops around like a fish out of water going between towns of higher importance, and it repeatedly veers off of the straighter routes between said towns, with the sole purpose seemingly to be to connect as many tiny towns as possible on the way. In addition, this simply lends a practical purpose to the classifications.)

• highway=secondary should include other (more minor) state routes, as well as major county routes that connect smaller towns and hamlets.
• highway=tertiary should include all other county routes.
• highway=unclassified should include any township routes, National Forest roads, and any other non-residential public road.

Overall, it would, in my view, be much simpler to add the quaternary routes into the equation here, especially since it would negate the need to force a restructuring of the entire classification system as currently set up. --TZLNCTV (talk) 03:04, 7 April 2020 (UTC)

Unlikely to be accepted and adopted

Just to avoid a disappointment in the voting phase, I would like to note that this proposal is unlikely to be accepted. Proposals changing the meaning of existing, well established tags have had it very difficult to get accepted in the past. Trying to change the meaning of a important value of highway=* requires all maps rendering minor roads to change their rendering rules. This is unlikely to happen within a few months. Roads disappearing because mappers follow new tagging rules will disappoint many data/map users. You will have many cases of mappers not using this tag because it is not supported by any map and it being new. Therefore, I suggest you to mark this proposal as abandoned.
If you had written this page on 1 April, I would have taken it as an April's fool. --Nakaner (talk) 07:12, 7 April 2020 (UTC)

New tagging rules, disappearing roads, and lack of adoption for fear of the above would not indicate a problem with the proposal; it would indicate a problem with the implementation process. You can't just switch everything over at once, of course, but you can get a ball rolling. For that matter, this same issue you have indicated could occur with almost any major tag change, depending on what kinds of tags a site is using as data inputs. To cope with the above problem, I would suggest the following measures being taken:

• 1) Introduction of an alternative interim tag (e.g. future_classif:highway=quaternary) to allow users to add roads as quaternary status during the transition period. This would preserve its existing classification for maps that have not yet updated, while adding the data to indicate that it will be reclassified as such when it is feasible to do so.
• 2) Coordination with the organizations that run rendering and routing systems based on OSM data, to notify of the change and get an idea of how long it would take them to implement it. As part of this, once each data system based on OSM data implements quaternary roads, they would notify the team in charge of the transition process that they have done so.
• 3) Upon support for quaternary roadways being added into the majority of mapping services, a series of mechanical edits can be made to replace the existing classification of a road with quaternary if the interim tag is present in the line's attributes.

With the above process in place, any short-term detrimental effects of the addition would be minimized. --TZLNCTV (talk) 14:53, 7 April 2020 (UTC)

Adding highway=quinary & highway=senary

Why not adding highway=quinary and highway=senary to the proposal (beside of highway=quaternary), with the long run goal to slowly expire highway=unclassified, even because the understanding of the term unclassified generates sometimes confusion and it isn't 100% intuitive for osm-beginners.--MalgiK (talk) 15:33, 7 April 2020 (UTC)

See also: https://wiki.openstreetmap.org/wiki/Proposed_features/highway:minor --MalgiK (talk) 15:59, 7 April 2020 (UTC)

what about primary

"In the United States at least, classifications typically take the following shape: Secondary for state routes, tertiary for a few major county routes, and unclassified for anything less than that." - what about highway=primary? Is it unused? Mateusz Konieczny (talk) 10:04, 23 July 2020 (UTC)

It varies, but in most of the United States highway=primary is used for most "US Highways": https://en.wikipedia.org/wiki/United_States_Numbered_Highway_System (See https://wiki.openstreetmap.org/wiki/Tag:highway%3Dprimary "U.S. Highways are mostly primary. Some State Roads are also primary, the criterion being either connecting large towns/cities, or being a major road in an urban area." also ) - in California and some other Western states there are few US Highways and the State highways serve the same function. Also see https://wiki.openstreetmap.org/wiki/United_States/Road_classification

(Personally I would prefer tagging US Highways as highway=trunk without regard to whether or not they are dual-carriageway; this would match usage in Britain, then State highways as Primary, etc. - but this is controversial, since most US mappers think that highway=trunk should only be used for "expressways".)--Jeisenbe (talk)

what about unclassified

Mapping mostly in rural Montana, I use highway=unclassified for most minor (county) roads, and that seems to work quite well so far. See e.g. Wheatland County, MT, with 2 highway=primary roads, 3 highway=tertiary roads (2 secondary state highways network=US:MT:secondary, one county road) and the other roads are unclassifieds (and service or track of course). Sorry, no highway=secondary in that county. --Lyx (talk) 10:01, 26 July 2020 (UTC)

In the area that I map usually there would not be a need to distinguish paved or unpaved unclassified roads, as basically all unclassifieds (as well as many residential, service and even tertiary highways) are unpaved. The surface tag should always be used for unpaved roads and should be sufficient to mark the difference IMHO. --Lyx (talk) 10:08, 26 July 2020 (UTC)

Sounds to me like the highway=tertiary should be changed to highway=secondary since you have them tagged as network=US:MT:secondary, and then the more importnat highway=unclassifed could be upgraded to highway=tertiary. In Britain where this started a highway=tertiary is often quite narrow and low-traffic, but connects a couple of small villages or hamlets together. --Jeisenbe (talk) 01:55, 15 January 2021 (UTC)