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How did you decide on routing engine? I’ve used Graphhopper in the past — is OSRM an improvement?

I actually tried a couple different engines before landing on OSRM. I started with R5 (since it can also do public transit) then switched to Valhalla.

The main limiting factor was speed. Basically all routing engines except for OSRM are too slow to compute continent-scale travel time matrices. For reference, it took Valhalla around a week to finish 3 billion point-to-point pairs. OSRM did the same calculation in about 2 hours.

I can't speak to Graphhopper since I haven't tried it. Maybe something to test in the future!

Makes sense! Heads up that Graphhopper’s matrix algorithm isn’t open sourced so probably won’t work for this use case. I’ve had good experiences with it otherwise.

Yeah OSRM precomputes routes so if you just need the same mode of transportation and not dynamic params (like avoid tolls on this route, etc) it's gonna be a lot faster. Valhalla was designed for flexible/dynamic routing

It precomputes partial routes that are combined at run time. :)

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