Spatial rules allow you to create rules for certain areas. One example is that the default accessibility for
highway=track in Austria is access=yes, whereas the default accessibility is access=destination in Germany. Other
examples are different max speeds for different countries. More information on different road rules can be found in the
OSM wiki, different accessibilities and
different speeds.
I you have a working GraphHopper setup it is easy to enable Spatial Rules, but they only work with the DataFlagEncoder.
We provide a set of approximate country borders, within the GraphHopper repository. If you need exact borders you can
get the exact borders from here. Go to your config.properties and
uncommend the line: spatial_rules.location and point it to where your rules are. You need to re-import your graph after
that.
Writing your own rules is simple. If you write a rule for a country that is not provided in GraphHopper yet, we'd love if you would contribute your rules. You can have a look at the GermanySpatialRule. Create something similar for your country. After that you have to extend the CountriesSpatialRuleFactory to match your country code.