[Talk-ca] Road designations

Adam Martin s.adam.martin at gmail.com
Thu Dec 11 14:10:54 UTC 2014

I have a question for the group regarding the designation of various roads
within city regions. Specifically, with reference to primary, secondary,
and tertiary roads. What exactly is the criteria being used to designate a
road as one or the other? I know that the wiki provides guidance, but it
does not appear that the guidance is always followed.

For example, this is an area inside Montreal:

​As you can see, there are two secondary one-way roads here (orange) and a
yellow tertiary road connecting them together in the lower right. I cannot
fathom why that roadway would be tertiary - it's just a simple connection
between the roads and should likely not be considered tertiary. Especially
given the guidance on the wiki "*The highway
<http://wiki.openstreetmap.org/wiki/Key:highway>=tertiary tag is used for
roads connecting smaller settlements, and within large settlements for
roads connecting local centres. In terms of the transportation network,
OpenStreetMap "tertiary" roads commonly also connect minor streets to more
major roads.*"

Here is another example along the same roadway in Montreal:

​Here we see a similar connection as before, but this one is designated as
a residential road. But we also get to see a very interesting thing occur -
the two one-way secondary roads suddenly transform into two tertiary
one-way roads. The problem here is that there does not seem to be a reason
for that changeover in the road type; the road continues as two one-way
roads through the Parc industriel d'Anjou area. The position of the change
also appears to be random or arbitrary.

I'm seeking a bit of clarification. I like to be cautious with changing
road types in regions just in case there is a reason I am not aware of for
them to be designated in this way.


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