[OSM-talk] Missing structure

Martin Trautmann traut at gmx.de
Thu Jan 17 23:39:21 GMT 2008


Karl Newman wrote:

> It seems to me we're going about this all wrong. Instead of splitting up
> ways just because any of its attributes change (or to break it up for a
> route), it seems like a way which denotes the same street (or other linear
> feature) should be as long as possible. Then we could hang attributes on
> subsections of it: i.e., for way 1234, the speed limit from node 5522 to
> node 5595 is 100 km/h. Or, way 1234 is a part of route "blue bus" from node
> 9553 to node 2558. Relations could accomplish this, but they don't have a
> rigorous structure to enforce all the parts/data integrity.

It sounds much more reasonable. Sinces ways are derived from the nodes, 
it should be more reasonable to add the speed limit to the node itself, 
but then including a direction in order to find the start of a speed 
limit. However, this would require a matching end designation, such as
   maxspeed = default
(or null or "-"...)

A reasonable assumption is that the matching speed limit in one 
direction is the end of a speed limit in the opposit direction. There 
may be many exceptions where speed limits apply for one direction only, 
or where start and end differ.

Merging segments by name and moving tags from segments to nodes could be 
done by a conversion script automatically.

- Martin




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