Utah/highway classification

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This is a proposal for standardized road classifications in Utah as part of a larger discussion about classification standards nationwide (United States/Highway classification). You're free to add on and edit the contents of this page.

This is a centralized page for rural Utah highway and other road classification.

Methodology

We use several different metrics to evaluate the importance of every highway. These include, but are not limited to:

  • Traffic counts
  • Road quality for motor vehicles (e.g. number of lanes, average speeds, pavement)
  • Number and quality of alternate routes available
  • Whether the roads connect any populated locations of note or serve popular recreation areas

We do not copy any of the governmental ways of classifying highways (functional class, US vs state vs county route, etc.), but we do use them as guides to help with the particulars.

Resources

UDOT Sources

Other Sources

Classification

Trunk routes

Corridor Endpoints Reason
US 6 I-15 to I-70 Major high-traffic route from anywhere in northern Utah to most places in southeastern Utah, anywhere in Colorado or New Mexico, and other points southeast. Most important long-distance non-freeway corridor in the state.
US 40 I-80 to Vernal Major high-traffic route from anywhere in northern Utah to the Uintah basin. Importance in Utah greatly diminishes east of Vernal; the classification of trunk or primary beyond that point should be left up to Colorado mappers.
US 191/491 I-70 to CO Major high-traffic route from anywhere in northern or central Utah to most places in southeastern Utah, southwestern Colorado or anywhere in New Mexico.
US 91 I-15 to UT 30 High-traffic expressway from the Wasatch Front to Logan, self-explanatory. However, the route north of UT 30 should not be trunk, as the road quality substantially degrades and the better route to Logan from the north uses I-15/UT 30.
UT 30 I-15 to US 91 Western half the route into Logan from the west and north via I-15
UT 16/UT 30 WY to WY This route provides the best route between SLC and Jackson, WY, via I-80, WY 89, and US 89. I would say that Jackson is a large enough destination that it should be served by trunk routes from the most major cities near it (i.e. Salt Lake City, Denver, and Boise). Most of the route, however, is in WY, and if WY mappers decide that WY 89 should not be trunk then UT 16 should not be trunk either.
UT 9/UT 59/US 89A/US 89 I-15 to AZ Part of the UT 59/AZ 389/US 89/AZ 98 east/west corridor. Although not united under one route number, this functionally serves as a major traffic corridor providing access to the St. George area from the east.
UT 7 I-15 to UT 9 Limited-access parkway that serves as an outer bypass of St. George.
US 50 I-15 to I-70 Route from anywhere in northern Utah to the Sevier Valley area, including Richfield. Serves as a shortcut from using I-15 to I-70, and slightly faster than using the UT 28 route. I could be convinced to downgrade this to primary if others don't think it's important enough.
UT 20/US 89 I-15 to US 89A Part of the fastest route from the Wasatch Front and other areas to Flagstaff. Probably the least important trunk route in the state, but just squeaks by.
US 189 (with UT 52 branch) I-15 to US 40 High-traffic expressway to Provo from anywhere to the east. Shouldn't need any further explanation.
UT 36 I-80 to Tooele Major route providing access to Tooele from Salt Lake City. It's close enough to SLC that I could be convinced that it's an urban road (and thus more deserving of primary), but I think it just crosses the urban/rural threshold enough to keep its trunk classification, and Tooele is a large-enough city that I think having a spur trunk route serving it is justified.
UT 224 I-80 to Park City Major route providing access to Park City from Salt Lake City. It's close enough to SLC that I could be convinced that it's an urban road (and thus more deserving of primary), but I think it just crosses the urban/rural threshold enough to keep its trunk classification, and Park City is a large-enough city that I think having a spur trunk route serving it is justified.
UT 85 entire length Urban expressway within the Salt Lake Valley and Utah Valley. Not fully completed.
UT 154 entire length Urban expressway within the Salt Lake Valley. Portions that are full freeways should have the motorway classification.
UT 201 I-80 to I-15 Urban expressway within the Salt Lake Valley. Portions that are full freeways should have the motorway classification.

Rural primary

Corridor Endpoints Reason
North/South
US 91 Logan to ID Most important north-south route through the Cache Valley. Importance in UT might justify trunk, but importance drastically decreases farther north in ID and paralleled closely enough by I-15, so keeping primary for now.
UT 252 US 91 to US 91 Non-limited-access bypass of Logan. For now keeping the section between US 91 (south) and UT 30 as trunk to keep trunk route continuity between the two, but in terms of importance the entire thing is definitely primary. However, if US 91 north of Logan is upgraded to trunk, then this probably should be too.
UT 165 Paradise to Logan Another major route connecting large towns in the Cache Valley to Logan.
UT 240/UT 38 I-15 to UT 30 I'm on the fence on this one. I'm inclined to say it's primary because it serves as the best route from SLC to Logan any time that US 91 through the mountains is closed or impassible (which happens during pretty much every winter storm). But on the other hand, when US 91 is open it's pretty clearly a secondary route in terms of importance.
US 191 US 6 to US 40 Low traffic, but it's the best and only feasible route to the Uintah Basin from anywhere in southern Utah, including St. George.
US 89 I-70 to US 6 Route serves multiple decent-sized towns in the Sanpete Valley. However, most people get to these towns using either UT 132 or UT 28 from I-15 rather than staying on US 89 the entire time; nobody would actually take this section of road from end to end to get anywhere.
UT 28 US 89 to I-15 The route from I-15 to the southern end of the Sanpete Valley, to towns like Gunnison and Centerfield.
UT 10 I-70 to US 6 The main route serving pretty much all of the towns in Emery County. However, it's not part of a longer important corridor like the nearby trunk routes of US 6 or US 40, so keeping at primary.
UT 260 UT 24 to US 50 Part of the fastest route from SLC to the Richfield area, via US 50.
UT 118 I-70 to UT 24 Pretty much the main street through the Richfield area. Parallels I-70 for its entire length, but the large distance between exits on I-70 means it serves much more traffic than one would think. However, I could definitely be convinced to downgrade to secondary due to how close it is to I-70.
UT 130/UT 21/UT 257 I-15 to US 6 The route to Delta from anywhere to the south, including important places like St. George and Cedar City. For the area it has quite high traffic as well.
US 89 UT 20 to I-70 Accesses all the places along the more important US 89 corridor south of UT 20 from both Richfield and places farther northeast. But quite a slow route with many twists and turns, and through various towns.
UT 18 I-15 to UT 56 The route into St. George from places in northeastern NV.
UT 17 UT 9 to I-15 The route into Hurricane and La Verkin from the north. Keeping as primary rather than trunk though, since it only serves this small area, and is almost more urban in nature than rural for most of it.
US 191 AZ to US 491 One of the more important roads through the Navajo Nation. I could be convinced to upgrade this one to trunk, as it's the route from almost anywhere in northeastern AZ to anywhere in northern UT. But I think with how remote this area of AZ is, it's better off staying primary.
US 163 AZ to US 191 Another important route through the Navajo Nation, but clearly a step below routes like US 160 and US 491.
East/West
US 89 US 91 to ID Route to Logan from the northeast, although there are no major population centers in this direction
UT 30 US 89 to UT 16 This is often the fastest route to Logan from the east, but is probably not the best route. It contains many sharp curves, slow speeds, two-lane roads with limited passing opportunities, and often has severe weather during winter. The best route to Logan from the east is instead I-80 to I-84 to I-15 to US 91.
UT 138/UT 179 I-80 to I-80 Access to Grantsville, which I think is a large enough city to justify a primary loop off of I-80. With the new guidelines, the UT 179 portion should not be trunk despite being an expressway.
UT 36/UT 73/UT 145 Tooele to I-15 Route to Tooele from places like Lehi, Eagle Mountain, Saratoga Springs, etc. From Provo or Orem it's usually quicker to go up through SLC and around on I-80, but I think these several communities are enough to justify a primary connection.
UT 248 UT 224 to UT 32 Western half is the access to Park City from the east; mostly an urban road. Eastern half is the best route to the Kamas Valley from almost anywhere in the state. Note that this results in a primary terminating at a secondary. I think a further discussion should be had about whether or not we want to upgrade at least part of the UT 32 loop off of I-80 to primary as well. Most people aren't going to take it to access the area (they'll take UT 248 instead), but it would result in more continuity between primary roads and it wouldn't be egregious to have it as primary.
UT 113 Midway to US 40 Route to Midway from Heber City, by far the most trafficked route into Midway. Like above, an argument could be made to have the section of UT 113 from US 189 to Midway also as primary, and I think it's worthy of more discussion.
UT 43 WY to WY I think this should be primary, but it's probably best left up to WY mappers since it's basically a WY state route masquerading as a UT state route.
US 6/UT 132 NV to US 89 The western portion is one of the more important routes across the extremely-remote West Desert, but doesn't serve any major corridor. I see no justification to upgrading this to trunk, as it is only really the fastest route between Ely and UT, or between Delta and NV. The eastern half connects the I-15 corridor to several decent-sized towns in the Sanpete Valley.
UT 116 UT 132 to US 89 Connects the UT 132 corridor to Mount Pleasant, which is large enough that I think a primary road is justified.
US 50 US 6 to I-15 Similarly to US 6/50 across the West Desert farther west, this just connects Ely NV to other places in Utah and beyond. Quite low traffic, but just important enough for primary I think.
UT 21/UT 160 UT 130 to I-15 Connects Milford and Minersville to I-15. I think this is a borderline primary; I could be convinced to downgrade it to secondary. The other section to the west across the West Desert is extremely remote and serves no connection of note at all, and is a clear secondary.
UT 56/UT 14 NV to US 89 The western section is an important route across the West Desert, serving as access to Cedar City from the west, and to St. George from northeastern NV. The eastern section is the access to Cedar City from the US 89 corridor, but the road is very windy and not quick.
UT 9 UT 59 to UT 17 See my comment for UT 17.
UT 24 US 50 to I-70 Western half serves a number of smaller towns in the Fremont Valley. The eastern half is the most important route in an extremely-remote region; it gives access to pretty much every place in this area and passes through the only town (Hanksville) in a vast swath of wilderness.
UT 12 US 89 to UT 24 Route to UT 24 and the Fremont Valley from places to the south, as well as a few small towns on the route. The western bit also serves as access to Bryce. A borderline primary, but I think it just crosses the line.
UT 46 US 191 to CO Route to the Telluride area from anywhere in UT
UT 162 US 191 to CO Important route through the Navajo nation; way more important than any other secondary routes in the area.


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