Time-Dependent Contraction Hierarchy

Hello community,

In the real world we have many junctions with time-turn restrictions, edges with traffic jams etc…
Using ALT and CH algorithms we need to preprocess a graph every time when the weight of endges are changed.

There are a few customizable algorithms e.g. CustomizableContractionHierarchy.

What are the prospects for using CCH(or other Time-Dependent algorithms) in GraphHopper?

Best regards, Storm.


Thanks for the linked repository and this sounds really interesting, especially as it is under a nice license and doesn’t look like the most complicated C++ :wink:

There are no plans now from us as with ALT such things are already possible. For most scenarios like traffic jams etc there is no re-preprocessing necessary unlike with CH, you can read about this in more detail in this blog post.

But of course: we would love having this! Maybe you have time and interests in a contribution to GraphHopper :slight_smile: ?

what is ALT?

The landmark algorithm (we use now “LM” to avoid confusion with alternative routes): https://github.com/graphhopper/graphhopper/blob/0.11/core/src/main/java/com/graphhopper/routing/lm/LMAlgoFactoryDecorator.java

Is there any update on this ask?
Is there any plan to implement customizable contraction hierarchies to accommodate hourly speed profile for routes?

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