Overlapping/Duplicate OSM Ways Create Duplicate OSMLR Segments

[dnesbitt61]

When OSM ways overlap they can create duplicate Valhalla edges. This can also occur when a single way is drawn with sections that overlap. This results in multiple OSMLR segments. It also leads to splitting or breaking OSMLR segments at the nodes where duplicates occur (leading to shorter segments than are desirable).

Ideal solution is to detect these overlapping ways and not create duplicate edges in Valhalla, though this has some complications due to OSM relations. Better tools to detect and fix the underying OSML data can be helpful here as well.

A second possible approach is to not create duplicate OSMLR segments - though this does not fix the issue with splitting.

Fortunately the presence of overlapping or duplicate ways is somewhat small. While inconvenient and leading to more OSMLR segments than are needed, the overall impact is likely small.