Very large networks

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In some situations you may want to work with very large street networks, which for one reason or the other is too large to handle (lack of RAM, you want faster calculations, licensing issues etc.).

 

One solution to such a problem is to delete the less important streets from the street database. This can typically decrease the size of a database significantly and most commercially available databases already has attributes for this kind of operation (e.g. select * where street_level>2). This also normally ensures that the rest of the streets still constitute a connected street network without any subnets.

 

The drawback is of course that all routes are limited to the selected street and driving directions very close to the start and end of the route will be missing. It will however still be possible to show a map with all streets and a signature of some kind, which shows the target, which is enough for many purposes.

 

The picture below shows an example, where the white streets has been omitted from the actual street network in the routing calculations, but they are still shown on the map, so the route starts a little away from the real start point: