OpenStreetMap
Along Pennsylvania’s freeways, there are emergency detour routes that allows travelers to bypass traffic accidents, inclement weather, and other road closures. Colors commonly used are black, blue, green, orange, and red. The detours are perhaps one of the least mapped features across Pennsylvania.
The best sources to consult are street-level photos from Mapillary and Bing Maps to establish which highways the particular route follows. I also recommend having a map nearby and to use colored pencils to mark the detour on the map.
Tagging the colored detours is quite easy using iD. Simply create a new Relation -> Route Features -> Detour Route.
Under Name, type in the name to be used, for example Orange Detour (I 79 Exits 121-130). Colors are used multiple times, so it is necessary to differentiate between them by including the ref for the highway being detoured and also the exit numbers that are being bypassed.
The Route Number in this case is Orange.
Because these detours are bidirectional, the from and to tags aren’t necessary.
The Colour tag would be orange.
Since I-79 is being detoured in this example, the Detour tag would be I 79.
Don’t forget to tag the directional role of the relation if the road being tagged is one way.
To make tagging easier, consult the OSM Wiki under the Detour page.
I have also published a YouTube video showing the best way of how to tag the relation.
I hope y’all find the resources helpful for adding the emergency detour routes across Pennsylvania.
Discussion
Comment from Minh Nguyen on 25 June 2023 at 15:30
Maybe it would be useful to create two relations, one in each direction, with the exit numbers as
fromandto, instead of relying on thenameto communicate that information?Comment from Longhorn256 on 28 June 2023 at 20:16
I’ve looked at other detour route relations, and they have it setup where it is just one, bidirectional relation with the roles determining the direction. Detour and Route Relations are also setup like this. Initially, when I did this, I wanted to be consistent with how OpenStreetMap approached this. This is definitely something to look further into, and I’d welcome more comments regarding this.
Comment from Minh Nguyen on 28 June 2023 at 21:10
Indeed, there are two mapping styles. The two-relation approach is an optional enhancement over the one-relation approach. It has some benefits, including less likelihood of breakage (especially scrambled member order) when other editors come in later to split a way or remodel an intersection, and a more robust way to tag the signposted cardinal direction, if any.
Comment from Longhorn256 on 28 June 2023 at 21:18
Since the two-relation (or three, including a superrelation) approach is best, I’ll go ahead and begin tagging using that way. Thanks for the link. It provided some helpful guidelines.