Clarifications on highway classification at complex intersections

[dknelson9876]

By “complex intersections”, I refer here to two separate cases that have received changes I’m not sure I agree with by user @Flap_Slimy_Outward in Salt Lake County, Utah.

First, the simpler case: a freeway interchange at a dual carriageway with different classifications on each end. For example, I 15 and Bangerter Hwy (SR 154). To the west, Bangerter Hwy is highway=motorway. To the east, Bangerter Hwy is highway=secondary. Since this is a Single Point Urban Interchange (SPUI), there’s a good handful of link ways involved.

This is the state after the most recent edits. Do you agree with the classification location as it is here, or would you move them to be symmetrical, or something else?

For another example of this type of interchange, see I 15 and 600 N, where 600 N is secondary to the west, and primary to the east.

Secondly, the case of a freeway interchange spread across multiple streets of different classifications. For example, I 215 exits 10 and 11, Winchester St and State St. For whatever reason, when this interchange was constructed, the ramps on the north side were connected to Winchester St, and the ramps on the south side were connected to State St. Most of Winchester St is secondary, but the portion between the ramps and State St is tagged as primary. This is the state it has been in for a while, and I agree with it.

The harder example for this case (and the one that’s been edited back and forth several times recently) is I 215 exits 3 and 4, Wasatch Blvd/3900 S/Upland Dr/3300 S. For reasons that escape me, this small area has 3 northbound on-ramps, 2 southbound on-ramps, 2 southbound on-ramps, and 1 northbound off-ramp.

I won’t even try to write out all the changes between classification for the roads that connect to the ramps, because it’s a lot. In this changeset, Flap Slimy Outward and Oregonian3 had a short discussion about whether this spread interchange qualifies short sections for higher priority. What do you all think is the best course to follow here, given that if classifications were continuous, these ramps connect to primary, secondary, and tertiary roads?

[dknelson9876]

@Flap_Slimy_Outward

Unfortunately, highway classifications aren’t always 100% symmetrical.

I’m not saying they should be symmetrical, I just want them to be consistent. This is why I intentionally didn’t state my preference on where the change is. And of course, I recognize that =motorway is an oddball for being a physical instead of priority description, and the reason you started working on a proposal, which I still need to read.

My point is that you came in and only edited a couple interchanges, introducing yet another pattern for where classification changes.

<tangent>

I’ll note that you already created extra work for other mappers when I had to undo your mapping of a dual carriageway where no median exists, which included a very questionable continuous =primary_link along the shared middle lane. </tangent>

If you look just at SR 154:

• At the south end it goes from secondary to motorway right after the light, but from motorway to secondary a bit before the light
• At 4700 S it goes from trunk to motorway right after the light, and from motorway to trunk significantly further back from the intersection
• At I 80 no signal is present, so it goes from primary to trunk when the first on-ramp joins, and from trunk to primary when the last off-ramp leaves

So it’s kind of consistent, but then look else where and:

• Where SR 201 goes from motorway to trunk, it happens in the middle of the intersection (along the intersecting road going from primary to tertiary at the same point)
• Where Mountain View Corridor (SR 85) goes from trunk to primary, it happens at the light on the far side of the interchange
• Where a road changes classification at SR 85 (Parkway Blvd, 9000 S, South Jordan Pkwy, 12600 S, or 13400 S, the higher classification continues to the light on the far side of the interchange
• At I 15 and 400 S, 400 S changes down at the last on-ramp leaving, and changes up symmetrically
• At I 15 and 600 N, 600 N changes up at the first off-ramp joining, and changes down symmetrically
• At I 15 and US 89 on the Salt Lake/Davis County Border, US 89 changes up with the off-ramp joining, and changes down with the on-ramp leaving

And I don’t even want to think about the more… unique interchanges in Northern Utah County.

@Flap_Slimy_Outward

• Primary designation goes from SR 171 eastbound to Wasatch Blvd southbound to 3900 South westbound to the ramp for I-215 southbound, while leaving the rest of Wasatch Blvd southbound as secondary.
• On I-215 northbound, take exit 4 toward Wasatch Blvd northbound, which is now primary. It stays that way until connecting with SR 171 westbound.

You forgot to mention the currently secondary portion of Upland Dr. If the map followed what you said, it would be the last ramp here that didn’t connect to a highway=primary. If you think that’s okay as is because it’s a weird in between ramp, then why upgrade that small portion from tertiary at all?

[Flap_Slimy_Outward]

Ah. Going west on Upland Drive, you can access I-215 northbound. Alas, it’s only a partial interchange, which is why it’s secondary rather than primary (a similar argument was made where a major arterial was upgraded from secondary to primary, but a user downgraded it due to it only being a partial interchange and having less traffic than another nearby primary road). So, I did something similar here.

Edit: “Why upgrade this tertiary portion at all?” Because the fact that it connects to a major freeway at all makes it more important than a road that doesn’t and would receive more traffic from drivers getting on/off the freeway.

[ezekielf (Zeke Farwell)]

@Flap_Slimy_Outward

this portion of Harmon Avenue is primary, while literally no other section is. That’s because it connects the primary portion of University Center Drive to Paradise Road at the place where their status as one-way roads ends. Because there is no way for drivers on westbound Harmon Avenue can access any other primary road, it is secondary.

It seems to me that you are over thinking highway classification down to a micro level. Highway classification is a high level, coarse piece of information this is mostly useful at smaller scales (lower zooms). Classification should generally change at an intersection. Nitpicking over the exact position where each carriageway should change classification within a complex intersection is silly. At the scale where the complexity of the intersection is visible, details like lane count, turn lanes, restrictions, width, surface, crossings, traffic signals, and such are far more relevant to data consumers than whether a road is classified primary or secondary.

I understand the logic you’ve laid out for why you classified each half of these dual carriageways differently, but I don’t see what benefit this provides.

Normally both halves of a dual carriageway get the same classification. Is there an actual problem for data consumers you are trying to solve here?

[Flap_Slimy_Outward]

@ezekielf

Normally both halves of a dual carriageway get the same classification. Is there an actual problem for data consumers you are trying to solve here?

First of all, I didn’t start this. This separation was actually done by another user. Furthermore, between Harmon Avenue and Russell Road, Paradise Road and University Center Drive are one-way streets (Paradise is southbound, University Center is northbound). Having that section of Harmon Avenue being primary connects the other two primary roads.

[Lumikeiju]

ref=WA * vs ref=SR * has also been discussed a few times in Washington (state), because ref=SR * is what is signed and actually used. (And I support using the ref=SR * variant)

[Flap_Slimy_Outward]

Hello, thanks for the invitation to a discussion. Now, to address your questions:

1. Unfortunately, highway classifications aren’t always 100% symmetrical. For example, this portion of Harmon Avenue is primary, while literally no other section is. That’s because it connects the primary portion of University Center Drive to Paradise Road at the place where their status as one-way roads ends. Because there is no way for drivers on westbound Harmon Avenue can access any other primary road, it is secondary. Similarly, this portion of Spring Mountain Road is primary, while the opposite carriageway isn’t. That is because the highway ramps were built differently, to the point where using them as highway classification criteria will result in the classifications being not symmetrical. In the example you gave (I-15/SR 154), I made the westbound carriageway a motorway after the traffic signals because that’s the last traffic signal, making the westbound carriageway a fully controlled-access highway. The eastbound carriageway, on the other hand, has a traffic signal before bridging over I-15. That traffic signal immediately disqualifies it as a motorway, since it is no longer fully controlled-access.
   1. What’s funny is that, for some reason, the primary designation continues after the motorway junction. (This what I mean by a “primary stub.”)
2. I haven’t edited this one, so no comment here.
   1. While northbound Wasatch Blvd makes sense being primary, the southbound direction does not, since there’s no way to access I-215 from there (see the comments I made for more information). What I would have done is this:
      1. Primary designation goes from SR 171 eastbound to Wasatch Blvd southbound to 3900 South westbound to the ramp for I-215 southbound, while leaving the rest of Wasatch Blvd southbound as secondary.
      2. On I-215 northbound, take exit 4 toward Wasatch Blvd northbound, which is now primary. It stays that way until connecting with SR 171 westbound.