I want to map some (a lot actually) of speed signs in Japan, but I’m somewhat confused.
Firstly, maxspeed is usually mapped on a way or the node?
I know the location of the speed signs and their value but I don’t know the distance that it is in effect, but I saw a lot of people cutting a way and putting a maxspeed on there.
Secondly, why is maxspeed:variable (according to the wiki) only allowed to be placed on a way? again, I know it’s a variable speed sign, but I’m not allowed to place variable speed sign on a node?
Another thing about maxspeed:variable. According to the wiki, it is said that if maxspeed:variable is set to yes, then the maxspeed tag is the maximum of the variable amount, but I don’t know what the highest value it can be set as, so how should that be mapped?
it also seems that in josm, maxspeed:variable on a node changes the speed sign icon from having a red outer ring and white center to a red outer ring and a black center. I don’t know why would this happen/if it is intentional given maxspeed:variable is not supposed to be tagging a node
The distance the maxspeed has an effect is very important, else you can’t really interpret the sign.
Typically, the maximum is either the national limit or the previous static sign in case the variable sign is “off”. At least this is the case with signs that are made with LED lights. With mechanical prism or folding signs you can usually determine the available signs relatively easily.
Also, if you really don’t know the value, you could always tag maxspeed=unknown (or just leave out the tag) and add a note=* or comment so someone else can add the value.
Likely yes, but it might depend on the local law. It is possible that in some regions it is something like “until the next crossing or the next sign, whichever is sooner”. Also sometimes signs tell you how long the limit is, e.g. a speed limit near a school typically only applies while near the school obviously.
Secondly, why is maxspeed:variable (according to the wiki) only allowed to be placed on a way? again, I know it’s a variable speed sign, but I’m not allowed to place variable speed sign on a node?
If the maxspeed:variable was only applied to a node, routing applications would be faced with the question of how long a variable speed limit should last and would have to make assumptions. It’s easier for us to explicity define the stretch that these speed limits apply to.
I’m sure a case could be made to add some sort of value to traffic_sign. The closest thing to use right now would be traffic_sign=variable_message