fallback_speed wrong units

[jjbringg]

Issue

Hi, I believe that fallback speed is using the wrong units. Specifically, if I take the distance in meters from the response and divide by the duration in seconds from the response, I see that the actual speed used in m/s is 10 times the fallback_speed provided in the request.

Steps to reproduce

Please provide the steps required to reproduce your problem.

• osrm-backend = 5.27.1
• OSM extract that was processed = planet
• Processing commands (e.g. CH vs MLD processing) = MLD
• Server queries = /table/v1/car/-81.58123608830448,23.133062732807502;-81.75449525435954,24.565179382517456?annotations=duration,distance&fallback_speed=1.6

Note that the response specifies a distance of "159594.4" meters and a duration of "9974.6" seconds. And 159594.4/9974.6=16 m/s. It is off by a factor of 10 from what was specified in the request.

I tried in multiple locations, not just here, and I found this factor of 10 error consistently.

Specifications

Postman request to osrm instance running in docker.

[jjbringg]

I would assume maybe the units are just off (though a 10m isn't a common unit, nor is a 0.1 second), but I saw elsewhere in documentation for OSRM (nodejs -

osrm-backend/docs/nodejs/api.md

Line 144 in 0ca9131

- `options.fallback_speed` **[Number](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number)?** Replace `null` responses in result with as-the-crow-flies estimates based on `fallback_speed`. Value is in metres/second.

) that osrm expects units of m/s for fallback_speed, so that probably isn't the issue...

[Rejudge-F]

I also encountered this problem. i think is a bug here.

[cv-or]

I also encountered the same problem. Example:

• I set fallback_speed = 16.6. I assume the unit of measure is meters/seconds
• I use the endpoint /table/v1/car/ on 2 points and I get this data back:
  'durations': [[0, 475.9], [475.9, 0]],
  'distances': [[0, 79005.4], [79005.4, 0]]}

I was expecting the duration to be = distance/speed. In my cause it would be 79005.4/16.6 = 4759 seconds, but in the response I see 475.9 seconds.