Alberta

The quick guide

• motorway': Highways which allow free-flowing traffic
• trunk: Highways 1, 2, 3, 4, 9, 16, 43, and 63
• primary: All other primary provincial highways (numbers 1 to 100, not including those already classified as trunk).
• secondary: Secondary Highways (numbers 500 to 899 and 900 to 999)
• tertiary: Major range/township roads in rural communities
• unclassified: Rural roads that are not part of the numbered highway system.

Highways should get a surface tag indicating paved or unpaved. If there is no surface tag, the assumption is paved.

Highways with two lanes in each direction (but without a divider/central barrier) should be tagged as lanes=4. If there is no lanes tag, the assumption is 2.

All highways should have ref tags added indicating the highway/road number. Those that are named (e.g. the Trans Canada Highway, Yellowhead Highway, Queen Elizabeth II Highway) should also have name tags.

The rationale

The highway tag in OpenStreetMap is intended to describe the official classification of a given road. At the same time, this is not enough information to draw a useful map.

The highway tag is used to record the road's official classification. It also carries certain implications regarding the road itself; notably, highway=motorway implies that the road is a divided highway, and both motorway and trunk imply limited access. However, the primary meaning of highway is the official classification. This naturally leads to:

• Provincial Trunk highways that are part of the National Highway System (highways 1, 2, 3, and 16) and ring roads 201 and 216: highway=trunk
• Other Provincial Primary highways (numbers up to 100): highway=primary
• Provincial Secondary highways (numbers 500 to 899 and 900 to 999): highway=secondary

Rural roads that are not part of this highway classification system can be tagged as highway=unclassified. This leaves the "in-between" status of highway=tertiary unused, but this class is useful when mapping important roads in urban areas.

In Alberta, the number of lanes on a highway can vary on the trunk highways, the lanes tag can be used to record the total number of lanes of travel on the highway including both directions (i.e. lanes=2 for a two-way highway with one lane each direction, lanes=4 for a street with two lanes in each direction with no divider, and lanes=2 on each way of a four lane divided highway with two lanes in each direction).

The surface of the road does not affect the highway's official classification, and so it does not impact the highway tag. But it is important information, and can be captured in the surface tag. Suggested values are surface=paved and surface=unpaved. Provincial highways and roads that are unpaved are gravel roads; for unclassified roads that are unsuitable for heavy travel (dirt, grass, really bad gravel), consider switching to highway=track.

Note that surface tag does not currently (May 2007) have any impact on the standard Osmarender or Mapnik layers, so the maps that OpenStreetMap creates will not differentiate between, for example, paved and unpaved Provincial Roads. This will hopefully change in the future. Custom Osmarender rulesets can be made that will incorporate this data. It should be noted that routing software might make use of the surface tag.

Winter roads (which are either closed or not maintained during the winter months) are not currently being mapped. If you map them, please give some consideration as to the sort of tags that should be used, and document that here.