Too long travel times - calculation inaccurate (too high)

openrouteservice
1

Dear ORS Team,

I am using ORS QGIS Plugin and am running my own ORS V8 instance. When I calculate traveltimes I experience huge differences (too long travel time but correct km distance) between ORS calculations and other engines (Valhalla, Maps, Openstreetmaps).
I have checked it with you demo instance, where I also receive the same results.
Let me give an example:

returns 46 minutes

Openstreetmaps:

Returns 32 minutes and 32 km

and Maps
"Google Maps
(Bezirkskrankenhaus Lienz to Rotes Kreuz Silian) 30 Minutes

This happens with a variety of cases, all displayed here

BVRD Transparenzlandkarte RD - (The number expresses the minutes to shortest next station from a matrix calculation) Almost all are too high.

Would be very grateful to get some insights what could be the problem.
Florian

2

Hey,

this is probably due to the acceleration heuristic, used to improve driving times in urban areas, that seems to be the culprit here.

Have a look at this issue on driving speeds that has a bit more information.

Best regards

1 Like
3

hi @jschnell -

can you hint me towards a solution - I’m using the docker Running with Docker | openrouteservice backend documentation
I fear that the ACCELERATION_SPEED_CUTOFF_MAX can only be changed when building it from source and changeing the cutoff max correct ?
Building from Source | openrouteservice backend documentation

4

Hey,

you may try setting use_acceleration to false, see the encoder options documentation in our backend docs.

Not sure if that will have the desired effect - if not, you’ll have to look at the source code as mentioned.

Best regards

5

Hi,

I think you should facing this issue after long time might be related to the speed profiles or road classifications used by your ORS instance which can significantly affect travel time calculations. ORS relies on specific profiles that might differ from those used by Valhalla Google Maps or OpenStreetMap leading to discrepancies in travel time despite accurate distance measurements. You might want to review the speed settings and profiles in your ORS setup to better align with the other engines or adjust the profiles to better match real world conditions.

Thanks

6

Hi,
as of now, it did have the desired effect. Thx.

1 Like
7

Hi again,

after upgrading to ORS V9, I experience yet again the issue, despite having set the use_acceleration to false.
My example shows a discrepancy between the to points
Point 0: 13.637017, 48.003171
Point 1: 13.716820, 48.004799

ORS V8 with use_acceleration: false
grafik
results in a 8.5 Mins drivetime

ORS V9 with use_acceleration: false
grafik
Results in a 14.28 min drivetime.

Tried to validate with Openstreetmaps and it returned

9 mins Drivetime

And Maps returned 9 mins as well.

In my ORS V9 profile I set the following and rebuilt the graphs.

profiles:
  driving-car:
    encoder_name: driving-car
    build:
      encoder_options:
        turn_costs: true
        block_fords: false
        use_acceleration: false
      preparation:
        min_network_size: 200
        methods:
          ch:
            enabled: true
            threads: 4
            weightings: fastest
          lm:
            enabled: false
          core:
            enabled: true
            threads: 4
            weightings: fastest,shortest
            landmarks: 64
            lmsets: highways;allow_all
      ext_storages:
        WayCategory:
        HeavyVehicle:
        Tollways:
        WaySurfaceType:
        RoadAccessRestrictions:
          use_for_warnings: true
    service:
      execution:
        methods:
          lm:
            active_landmarks: 6
          core:
            active_landmarks: 6

Is there anything else I can do in V9 to gain results as seen in V8 by disabling accelerate?

Thanks
Florian