New in OSM Inspector: Highway relations and out-of-use roads

A few days ago we have added a couple of new road-related layers to our OSM Inspector.

Relations with highway=*

In the past, highway=* was sometimes added to route relations (type=route + route=road). This is not in line with current tagging standards any more, and can even lead to duplicated line geometries when importing OSM data into PostgreSQL with Osm2pgsql.

The layer shows these old-style relations in dark red.

Not all relations with highway=* are a problem – for example, pedestrian areas and rest areas mapped as multipolygons relations (type=multipolygon) are totally fine and hence not shown as errors. This exception applies to multipolygons with a highway=* value of pedestrian, footway, service, rest_area or services.

Multipolygon relations with other highway=* values are likely candidates for changing to area:highway=*. See the OSM Wiki page aboutarea:highway=* for details about mapping roads as areas.

Out-of-use Roads

Even though OSM records “facts on the ground” and not historic or future data, it is generally accepted to map roads and paths which are not in use any more (or are not completed yet).

In recent years, the so-called Lifecycle Tagging Schema was adopted by many mappers and is used to tag feature which are not actively used any more, are (partially) removed or expected to be created in the future. The schema works by adding the lifecycle state as a colon-separated prefix to main key of the feature. If a road tagged as highway=secondary becomes disused, the tag is changed to disused:highway=secondary. Other tags of the feature remain unchanged.

(An older, but equally valid, way of describing lifecycle states is to put highway=construction together with construction=secondary. The new OSMI layers treat both methods in the same way.)

The following lifecycle sates are in use:

• razed or dismantled or removed (note that the use of these prefixes is often subject to discussion and may be discouraged in your region)
• abandoned
• disused
• in use (normal state)
• construction
• proposed (note that mapping proposed features may contravene the on-the-ground mapping rule and may be discouraged in your region)

OSM Inspector now has four new layers displaying all linear highway=* features which are abandoned, disused, under construction, or proposed.

Two new layers render frequent mapping mistakes:

• Red: If a way has tags of contradicting lifecycle states, it is rendered on the Multiple lifecycle states layer in red. There can be valid reasons for such tagging, for example when a minor road is reconstructed to be a larger road (or a track in the forest is not maintained any more and becomes a narrow path). But in most cases this is an error.
• Orange: If the old method of lifecycle tagging is used in an incomplete way, e.g. highway=construction without a construction=* tag), this is considered an error. Sometimes the correct tag value can be discovered from the object history; otherwise a survey is required.

Use quality assurance tools responsibly

Please use quality assurance tools responsibly. They are often wrong. And even when they point you to poor mapping, simply repairing the mistakes is not a good choice. Poor mapping is often a sign of lack of knowledge (e.g. newbies), bad intentions, or mechanical edits, organised editing or imports gone wrong. It is worth having a look at an object’s history and other edits by the mappers involved to avoid simply “cleaning” the map and therefore possibly hiding a systemic issue. When contacting others about mistakes they have made, always remember that we all make mistakes and we can only become better by supporting each other.