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#1 2020-09-02 12:32:43

Registered: 2019-12-01
Posts: 6

Current tertiary/secondary distinction is problematic

The tagging standard for Lithuania as given on the OSM Wiki is that highway=secondary is for paved roads outside of cities, and highway=tertiary is for unpaved roads. The OSM community in Lithuania (or perhaps just one particular editor, Tomas Straupis) monitors OSM for changes to these tags and reverts (and without any discussion first).

Because the tertiary/secondary distinction is subjective in the absence of official classification, basing tagging on whether the road is paved or unpaved for its entire length is a reasonable rule of thumb. However, strict enforcement of this guideline has led to some absurd situations, where mappers are unable to verify any change in the road on the ground. For example:

Bridges Usually when a bridge is built on a tertiary road over a waterway, there will be some kind of paved surface (asphalt or concrete). According to the strict guideline, this means that a 3-meter-long bridge section of road that is paved on an otherwise unpaved road, must be changed to highway=secondary. An example of this is at 54.0973870, 23.5322297. I traveled here today and I was unable to verify any significant change in the road other than the surface.

Brief paved sections within villages of roads that are otherwise unpaved. There are a number of cases in Lithuania where an unpaved rural road is paved with asphalt for several hundred meters as it passes through a village, but it immediately reverts to an unpaved road at either end of the village and it does not connect to any other highways. Strict application of the tagging rule means that this paved section must be changed to highway=secondary. However, a mapper on the ground cannot verify that the road has changed towards a higher level of road classification. (In fact, it is the opposite: usually speed limits are lower on these portions, and the road is perhaps narrower).

It seems to me that this tagging standard is very old, predating the widespread usage of the surface= tag, and it was originally an attempt to distinguish between paved and unpaved roads for the sake of rendering or routing. However, today routing engines take the surface= tag into account, and it is possible for renderers to show road surface independently of road classification. Therefore, this Lithuania-exclusive standard is no longer necessary.

Consequently, I propose that this tagging rule be changed to the following: "Outside of cities paved roads should be tagging as highway=secondary, with the exception of very brief paved portions (e.g. bridges) of roads that are otherwise highway=tertiary for the rest of their length)."

I would like to get the input of more members of the community, and I would like to see how many people other than user Tomas Straupis support the strict application of the original rule.


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