How do I add an area that is a road under construction.

General talk
1

While travelling this year, I came across an area that they are building a new road to replace part of the highway to cut out part of a winding road. I want to know how to add this feature to the map. From what I saw, it may be completed before winter.

2

Check out the lifecycle prefix https://wiki.openstreetmap.org/wiki/Lifecycle_prefix. In a case like this it could be tagged as

construction:highway=motorway|trunk|primary|whatever

An alternative would be to use the highway=construction tag https://wiki.openstreetmap.org/wiki/Key:construction#Highways. In which case the tagging would be something like:

highway=construction
construction=motorway|trunk|primary|whatever

Since the two tagging methods don’t conflict, you could even use both:

construction=motorway|trunk|primary|whatever
construction:highway=motorway|trunk|primary|whatever
highway=construction

I am not sure if any data users (renderers, routing, navigation apps) use any of the above so it probably doesn’t make much difference which tagging you use. It is mostly information for the next mapper to come along, especially after the construction is complete.

3

The most common way to map a road under construction is highway=construction, construction=*, where * is the value of highway after construction (e.g. motorway, tertiary). This is the second tagging scheme from n76’s post and it’s supported by most data users.

A lifecycle prefix is generally not used for highways and therefore not supported by most data users.

edit: The highway=construction tag is meant for the road itself (the line). You can add the construction area as a landuse=construction.

4

And, of course, the opposite is also true: It’s generally not used for highways because it’s not supported by most data users.

Your answer is absolutely correct, but I feel that we should ideally transition to lifecycle prefixes for highways in the long run. We’re using them for almost everything else, and the special exception for highway/railway seems to exist purely for historical reasons. So I like n76’s recommendation to use both: One for compatibility with existing software, the other to help us get rid of historical baggage.