[OSM-talk] Very long ways

Lars Aronsson lars at aronsson.se
Wed Mar 28 07:17:47 BST 2007

As I gain experience from working with JOSM, I'm seeing problems 
with long ways that are incompletely loaded into JOSM.  The other 
day I tried to split E4 in Sweden and E75 in Finland into shorter 
pieces, and I'm not sure I didn't ruin some of it.  When I'm 
creating new ways, I'm trying to break them into pieces of 40-140 
segments each.

Are there any guidelines for how long ways should be?  Either by 
number of segments or by geographic size?

When I was looking in planet.osm for extremely long ways [*], I 
found coastlines.  For example, way id="4318034" has 5575 segments 
and these tags:

    <tag k="natural" v="coastline" />
    <tag k="created_by" v="JOSM" />
    <tag k="source" v="SRTM" />

It seems inevitable that these large objects will be hard to 
handle.  Is this a good design?  Should clients (like JOSM) be 
required to handle long ways?

Some long ways that aren't tagged as coastlines are:

 Number of  Way ID        Way name

      4885  id="4272608"
      4531  id="4199238"  "NA-RM  AV"
      3842  id="4279603"
      3823  id="4272602"
      3801  id="2281835"
      3657  id="4045850"  "الطريق  مراكش  وارزازات"
      3123  id="4276688"
      2216  id="3870479"
      2098  id="4057540"
      2059  id="4045849"  "N1"

[*] The following script finds long ways:

  awk '/<way /  { a=0; id=$2; }
       /<seg /  { a++; }
       /<\/way/ { print a, id; }' planet.osm |sort -nr

  Lars Aronsson (lars at aronsson.se)
  Aronsson Datateknik - http://aronsson.se

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