Talk:Illinois/Highway Classification

Good start

I never decided to create a specific highway classification for IL because it was based off the [United States/Road classification] which I defined at the same time way back in the day when OSM was a new thing. I know some states like Texas have special circumstance roadways they like to class differently but I didn't really see any in IL. There are though some roads that switch classes depending on their characteristics, like LSD which is mostly a motorway, but downgrades to a trunk downtown where it passes though intersections. I guess this page could help clarify to people why that is with specific listings of routes and hope people read it. Good start so far. I'm sure if done correctly, it can look better than other state classification pages. --Nickvet419 . 19:45, 19 March 2022 (UTC)

Good start! I think it is worth exploring an IL specific classification page, even if we just discover the US guidelines are sufficient. We might find some regional differences in the process. Aren't the second and third motorway bullets saying similar things? Also sometimes the motorway begins/ends with an at-grade intersection. See I72 in Champaign for example. Invidious (talk) 15:52, 20 March 2022 (UTC)

Yeah, LSD is definitely one of the prime urban examples of a motorway / trunk. In general, I think we're under-utilizing the trunk tag, and over-using primary and lower. In Chicago in particular, there seem to be a lot of higher-classification roads that don't warrant it, recalling my own experience of getting around the city back when I lived there. --Jdcarls2 (talk) 02:18, 21 March 2022 (UTC)

US Routes

I think that in general, most US routes are probably primary, maybe secondary. But I would hesitate before making "is a numbered US Route" equivalent to a highway class in OSM. I can think of a few, just in and around Kendall County, that would definitely not be the primary route between two points.

Yeah, I added that as a starting point but even I have reclassified some to tertiary where they are obviously not the primary interconnecting roads. Invidious (talk) 06:40, 21 March 2022 (UTC)

shouldnt declass roads based on how they feel. If they are marked routes, State or US, they were done so by as a Functional Classification and not by if someone prefers another route or thinks other roads are more widely used. --Nickvet419 . 05:19, 28 February 2024 (UTC)

Did you review the maps from IDOT? They identify multiple routes as "Minor Arterial" which would be the equivalent of "tertiary".--MBriganti (talk) 14:57, 28 February 2024 (UTC)

Traffic Counts Model

I'm toying with the idea of using traffic count data to try and come up with some kind of model to help identify important routes. Anyone have any experience with anything like that?

Only if you want the map to look like a live traffic map. I'd stay away from traffic counts and how a road feels and stick with more definable characteristics. For upgrading class, Is the road a designated route? In Urban areas, Is the road residential or business lined? Does the road dead end or does it cross a river or highway? --Nickvet419 . 05:15, 28 February 2024 (UTC)

Traffic Count data can assist local and remote mappers by understanding a road's relative importance to the local network. Whether or not the road is a designated route does it automatically impact its level of importance - it provides a clue, but not the answer.--MBriganti (talk) 14:57, 28 February 2024 (UTC)

Trunk is based on physical characteristics?

In line with how other states are applying highway=trunk, the definition here should better reflect the role of network connectivity (i.e. trunk roads connect regional centers) rather than physical characteristics. It even looks like we have already identified the regional centers. --Popball (talk) 22:48, 16 June 2023 (UTC)

completely agree!--MBriganti (talk) 14:57, 28 February 2024 (UTC)

Detailed Definitions

I made a big update to this page, but I want this to be an open discussion. What do you think about the definitions? How can they be improved?

In my opinion, the biggest issue at the moment is that it provides two different contradicting definitions for classification. Most notably {{tag|highway|trunk} is according to this page either:

a. Roads that exhibit most of the characteristics of a motorway

b. Roads which connect importation regional destinations (the list defined in "Important Populations Centers for Trunk/Motorway Network"

I'd say we should reorient more towards (b) as it by consensus is what most of the US is doing for highway classification.

Also, we can probably get rid of most of the more minor classifications from this page (those with service=* tags for example) unless they have any information helpful to classification in Illinois specifically. --Popball (talk) 13:04, 5 October 2023 (UTC)

I agree! Physical characteristics can probably be adequately conveyed by other tags, like expressway=*. Linking physical characteristics and classification is going to involve arbitrary distinctions and likely to get messy. --Jdcarls2 (talk) 14:43, 5 October 2023 (UTC)

Primary were set as State and US routes and some main roads in urban areas as they already connect town centers across the state. Some would be upgraded as Trunk if they were built as high speed expressways but with some at grade intersection. If they were based on connectivity, then every US and state route would be a trunk. --Nickvet419 . 23:03, 26 February 2024 (UTC)

This is factually incorrect. This may have been true during the tiger import days, but it is not relevant anymore. You can't apply a one-size-fits-all definition. There are local factors to take into account. Case in point- IL state routes 31 and 25 are in no way a primary route for the locals. Orchard Road is a county route and it sees twice as much traffic as IL31 and four times as much traffic as IL25. Route 47 is absolutely a trunk as it connects 88 to 80 and the 56 spur.--MBriganti (talk) 00:57, 28 February 2024 (UTC)

County/state/US/Interstates have a default, but are classed higher based on local factors. Roads are not classed based on the amount of traffic they see or by how one local might view it. otherwise the map would basically be a live traffic map and impossible to classify. --Nickvet419 . 23:57, 27 February 2024 (UTC)

Where is your source that County/State/US/Interstates have a default? Look at any of the Functional Classification Maps from IDOT. IDOT does not use a default as that misrepresents the network. Network importance is the primary goal of the 2021 US Highway Classification Project.--MBriganti (talk) 00:57, 28 February 2024 (UTC)

2021 US Highway Classification Project notes Primary as "US highways, business loops on the interstate network, higher-importance state roads, and roads which provide connectivity to minor population centers" but that page is only a guidance for State-specific classification standards. Illinois started out defaulting county signed roads as tertiary, state as Secondary, except in urban areas and US as primary. I know that because I wrote those standards back in the day as they were similar to the US standard which I was also working on. That was eventually rewritten and the standard became that state roads were also included in the primary class as they were also designed with functional classification. But as OSM mappers we have to come up with our own way of mapping that doesn't outright plagiarize other mapping companies or governments and that utilizes the tags provided by the OSM community like "Trunk". --Nickvet419 . 03:00, 28 February 2024 (UTC)

I appreciate your contribution to OSM 15 years ago, however, applying blanket classifications and disregarding local mappers is disrespectful. You are conveniently misrepresenting what the 2021 US Highway Classification Project states about Primary; it does not define a default nor should it. Roads should be based on their relative importance to local transportation.--MBriganti (talk) 14:57, 28 February 2024 (UTC)