[Talk-us] Trunk VS primary,

[Evin Fairchild]

Okay, this is going to be a long message, but I’d strongly suggest you read ALL of it before responding.

I’d first like to address the assumption that some people seem to have that those who support using trunk on roads other than divided highways are “tagging for the renderer” because we allegedly just want to see these roads appear at lower zoom levels. For me, that is NOT the case at all.

In reality, I support having trunk for major intercity highways because there needs to be more levels of indicating importance for US highways than just primary. For example, in Nevada, US 50 and US 6 are very lightly-traveled roads that only connect a few small towns in Nevada, and are known for having very little traffic. Tagging them as primary is perfectly fine IMO. However, US 95 connects the two biggest cities in Nevada—Las Vegas and Reno—but it’s also tagged as primary. Surely US 95 between Vegas and Reno is more important than US 6 and US 50, right?

In my home state of Washington, there are two US routes that cross the Cascade Mountains, US 12 and US 2, both currently tagged as primary. Both of these roads are kept open in winter thru the Cascades. However, there is another road that crosses the Cascades, WA 20, that is also currently tagged as primary (which makes sense given that it is a very important cross-state highway), but it is NOT kept open in the winter. It doesn’t make any sense that a road that is not open in the winter is tagged at the same importance level as other roads that are kept open in the winter!

Secondly, I think some things from the wiki need to be pointed out here. On the wiki page for Key:highway, [1] the definition of highway=trunk is “The most important roads in a country's system that aren't motorways. (Need not necessarily be a divided highway.)” Those who say “Trunk roads should ONLY be divided highways, no ifs, ands, or buts” are going against what is explicitly stated on the wiki page for key:highway. 

Also, at the bottom of the aforementioned wiki page, there is a section entitled "Assumptions,” which states in the first paragraph: 

“Only highway=motorway/motorway_link implies anything about quality. Other road types, from highway=trunk through highway=tertiary to highway=residential=residential/service or highway=path/footway/cycleway/track do not imply anything about road quality.” 

These words speak for themselves. 

Now, if we want to indicate road quality in some way (e.g. whether a road is divided or not), we ought to use the expressway=* tag like others have suggested rather than using the highway=trunk tag just for that. 

Even if you don’t use the expressway tag, you can still tell if a trunk road is divided or not because the default render shows divided roads as having a thicker line than undivided roads. A good example can be seen by looking at western Canada, where the most important intercity roads are tagged as trunk regardless of whether they’re divided or not. [3] You can clearly tell if a road is divided or not even if undivided roads are tagged as trunk because the divided roads have a thicker line than the undivided. Therefore, it is not necessary to reserve highway=trunk for divided roads only.

TL;DR I support tagging undivided roads as trunk because 1) some US routes are more important than others and lumping them all as primary doesn’t make any sense; 2) the wiki says that only the motorway designation implies anything about quality of the road; and 3) the renderer shows divided roads with a thicker line than undivided roads. 

[1] https://wiki.openstreetmap.org/wiki/Key:highway#Roads
[2] https://wiki.openstreetmap.org/wiki/Key:highway#Assumptions
[3] https://www.openstreetmap.org/#map=7/51.618/-112.972

From: Greg Troxel
Sent: Tuesday, December 17, 2019 1:16 PM
To: Paul Johnson
Cc: Mike N; talk-us at openstreetmap.org
Subject: Re: [Talk-us] Trunk VS primary,

Paul Johnson <baloo at ursamundi.org> writes:

> On Tue, Dec 17, 2019 at 7:24 AM Mike N <niceman at att.net> wrote:
>
>>
>>    I think many of the trunk VS motorway VS primary conflicts come from
>> 2 points of view:  on the one hand, people like to zoom out and see a
>> coherent network of interconnected roads.
>
> In which case, rendering based on network on the route relations would be
> more appropriate.

This is the crux of the matter.  Calling things trunk so they render is
tagging for the renderer in a bad way.

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