In the USA, partly because we are such a geographically large part of the North
American continent and partly because each of our fifty states is sovereign, I
find that breaking apart very large relations so they are across a single state
at a time (then perhaps these are collected into a super-relation) is often
(though not always) a sensible approach. It is part size (large relations with
vast numbers of members are unwieldy), it is part “what sort of an entity is
this politically?"
For example, there is a note in OSM’s Amtrak wiki page on the route=train
relation for the California Zephyr: "The relation is said to be so big it is
hard to work with.” That is something we might take to heart and break apart
the relation into statewide components. I haven’t done that, but somebody
might, after considering that it makes editing easier, and that state-at-a-time
is a good way to do this. Even a simple web browser request to display this
relation results in "Sorry, the data for the relation with the id 905830, took
too long to retrieve." The practicality of potentially better avoiding edit
conflicts has been mentioned, and is also true.
The number of elements in this Zephyr relation is over 2500, and that can make
editing and display difficult. When OSM bumps up against real limits of
practicality like this, we should pay attention by discussing strategies like
subdividing using sensible approaches and methodologies. It may not always be
obvious when to break apart a large relation into statewide components, but
neither should it surprise us when somebody (for reasons of logical
subdivision, practicality or both) does so.
SteveA
California
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