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Up until very recently, I did not use highway=unclassified at all. Somehow, I had initially understood it to mean 'unknown'. So now I have read up on the ambiguity and the controversies associated with it, and came away with the impression that highway=unclassified is very much applicable to many roads in the suburban US and should be used. Potlatch2, actually, is being helpful by offering "minor" as a choice in the menu, which it translates to the 'unclassified' tag.

I figured if the street is small (e.g., one lane in each direction) but does not provide access to residences and is rather used to connect residential neighborhoods, it's unclassified/minor. I pretty much literally go by the little pictures Potlatch2 uses to illustrate each classification: if there are trees on the sides and not houses... there you go! :)

Another rule I worked out for myself is that if a road is used as an access road to an area of the city (I tag those as place=suburb following a brief discussion in the forum), I will not tag it below 'tertiary'. These areas/suburbs with population anywhere between 3,000 and 10,000 are often walled off and have only three to four roads leading into them. I want the rendered map to show such access points clearly - and colored roads achieve this nicely.

Does this sound unreasonable to anyone?

asked 15 Apr '11, 00:27

ponzu's gravatar image

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edited 15 Apr '11, 00:50

The answer this question probably depends a little on the conventions used in your country. In some countries there is a distinct difference between highway=tertiary and highway=unclassified, but in others highway=unclassified is simply a more minor road.

For the USA, the United States roads tagging page is probably the way to go. Many countries have similar pages. See also the International Equivalence section on the Key:highway wiki page.

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answered 15 Apr '11, 05:16

Ebenezer's gravatar image

accept rate: 9%


Here's the thing. The two pages you linked seem to contradict each other. And if I track down other pages I have read on the subject, they will probably add more ambiguity - on the subject of 'unclassified' roads more than any other. The first page you linked says that roads smaller than tertiary should be tagged as 'residential' if they are in residential areas. The seconds says 'unclassified' are "other roads used for local traffic. Use highway=residential for local roads with residences." Hence my post. I tried to simplify the rules and wanted to see if it will fly.

(15 Apr '11, 05:31) ponzu

People tend to use unclassified to indicate a more minor road outside of residential areas. e.g. small rural roads.

(28 Apr '11, 08:16) Ebenezer

From a UK point of view a tertiary road is a 'C road'. The difficulty here is that very few are signposted and the numbering system is used internally by local highway authorities.

I have seen some information on the web, but am not sure how usable it is as it is based on OS mapping.

I suspect that C roads are the ones that get gritted during the winter, and every village should have at least one.

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answered 17 Feb '12, 17:04

trigpoint's gravatar image

accept rate: 13%

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question asked: 15 Apr '11, 00:27

question was seen: 15,045 times

last updated: 17 Feb '12, 17:04

NOTICE: is no longer in use from 1st March 2024. Please use the OpenStreetMap Community Forum