Driving Time Calculation Issue with Highway Speeds

openrouteservice
1

I’m noticing a discrepancy in driving time estimates for longer routes on OpenRouteService, especially when using highways. For example, over a 150 km route, the calculated travel time seems too high, as if the system is assuming a lower average speed typical for non-highway roads, even when the route includes highways (Bundesstraße gegenüber Autobahn).

When I check the routing details, some highways seem to be classified or treated as major roads (non-highways), which could explain the slower average speed assumptions. This issue becomes clear when I compare routes: If I choose “avoid highways,” the route changes correctly, but the initial calculated time seems based on lower average speeds (as if using major road speeds for highways).

If I calculate 150km at an average of 60km/h, I get about 2:45 hours. If I calculate 150km at 80km/h, I get 2 hours. Which is also realistic to Munich with the truck.

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  1. Does OpenRouteService indeed use lower speed averages for highways, possibly by mistakenly applying major road speeds for time calculations?
  2. Is there a way to adjust these speed assumptions manually, perhaps by changing parameters or configuration settings to reflect more realistic highway speeds?

Any insights or configuration tips would be greatly appreciated!

2

Thanks for reaching out and bringing the described issue to our attention!

On a general note, please keep in mind that even though your example route predominately involves a motorway, the parts at origin and destination run on smaller roads within a city with reduced speed. An average of 80km/h is only possible to maintain when staying on the motorway. Nevertheless, even for a pure motorway section of the route of length 120km the reported driving time is about 2h, which indeed results in an average speed of 60km/h

The travel time is estimated based on different heuristics which try to account for possible delays due to traffic conditions etc. One of them is the so called acceleration heuristic which models speed fluctuations on smaller streets. This, unfortunately, can also result in overall speed reduction on motorways. You may try turning it off by setting use_acceleration=false under encoder options in your ORS config file.

Cheers,
Andrzej

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3

Thank you for the tip. This was really helpful. The tour to Munich changed from 2.5h to 2h and to Dortmund changed from 9.5h to 7h. Both of which are much more realistic.

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