If I want to calculate total way length, is this query a good way to do it?

Hi,

If I wanted to calculate the total length of highway ways in OSM, would this query be a good way to achieve that if I have an osmosis (snapshot schema) database with linestring extension?

select tags->'highway', sum(st_length(linestring::geography)) from ways where tags?'highway' group by tags->'highway' order by sum desc;

Here are the top results for a small (Utah, USA) database:

length statistics postgis

asked 31 Oct '14, 23:18

mvexel
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accept rate: 0%

edited 31 Oct '14, 23:21

This thread may be an interesting read:

http://gis.stackexchange.com/questions/63762/why-is-sum-of-st-length-of-segments-20-too-big

(01 Nov '14, 06:39) mmd

One Answer:

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It certainly does look like it's working ;) If the reason you're doing this is that you want to compare with existing statistics, remember that your query will count the total way length in OSM, whereas official statistics will occasionally throw together both carriageways of a dual-carriageway road, yielding a smaller total length.

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answered 01 Nov '14, 00:39

Frederik Ramm ♦
82.4k●92●720●1272
accept rate: 23%

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postgis ×134
statistics ×18
length ×16

question asked: 31 Oct '14, 23:18

question was seen: 5,921 times

last updated: 01 Nov '14, 06:41

If I want to calculate total way length, is this query a good way to do it?

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