File:OSRM Example Leipzig-Gruenau W2W TR misinterpretation.png

Summary

This is the last in a series of 16 files giving examples of how http://map.project-osrm.org/ handles routing over a lane-mapped, TR-enabled intersection. In 15 of 16 cases it does a superb job.

This image here is the _only_ example where the routing algorithm produces wrong results, presumably because it does not adhere to the specification depicted in Relation:restriction fully.

The specification clearly states that ways in via are allowed, but OSRM does not seem to handle them (yet) and simply ignores the turn restricition present in the data. So this is NOT a problem in the data, the turn restriction preventing this move exists. It is however a problem with the routing engine not implementening certain types of turn restrictions.

Instead of running around, reverting each and everything to conventional pre-2005-state-of-the-map mapping, people should adjust their routing engines to allow or disallow cases mappers have already carefully cared for. The consequence of an incomplete adoption of the turn restriction relations in routing algos is that there are fellow elphs out there, thinking this is how routing ought to work:

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