[Routing] Errors in map data that affect correct routing - and what to do about it...

Wolfgang W. Wasserburger osm at wasserburger.at
Mon Jan 5 23:27:54 GMT 2009

> Wolfgang - you mentioned breaking Ways at crossings with other
> Ways. Do you not then lose information about how the Ways
> interact? I haven't looked closely at the data in Edinburgh yet
> but I was hoping that the manner in which Ways cross each other
> would give me information on which Way has 'right of way'., i.e.
> if 2 Ways meet at a node such that the degree of the node is 3 or
> 4 and the junction is not a traffic light or roundabout then one
> of the Ways is a 'major' road and traffic on it has priority, the
> other is then a 'minor' road and traffic on it must 'give way'.
> It may not always be possible to tell from the tagging which road
> is the 'major' but in some cases a hierarchy should give it i.e.
> highway=unclassified gives way to highway=primary.

Yes, roads should share a common node on crossings, but in many cases the
same way id is used before and after the crossing. So I break these ways up
into two routing records pointing via way id to the original data.

Hope thats clearer now.

CU Wolfgang

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