Milton,
OSRM depends on the tags in OpenStreetmap to estimate travel speeds, and it
is not always right. For this particular route, it looks like we think the
speed is about 60km/h based on the road tags.
You can see what OSRM thinks of the underlying road network on the debug map:
http://map.project-osrm.org/debug/#17.65/8.51453/76.97262
<http://map.project-osrm.org/debug/#17.65/8.51453/76.97262>
The road is unnamed, and has a `maxspeed=60` tag on it. We assume cars will
drive at approximately the speed limit.
I do not know where TravelMath gets their routing results from, but there's a
good chance they are using Google behind the scenes. Google uses data from
mobile phones to get better estimates for travel speeds on roads, this leads to
more realistic ETA calculation. Unfortunately, that kind of data is all
private, so OSRM does not have access to it. The best we can do is estimate
based on the metadata we have in OpenStreetmap.
If you have your own source of improved driving-speed data, you can set up
your own OSRM server and import it using the "traffic data features" (see the
OSRM Wiki).
To answer your other questions:
- Do you want shortest distance routes, or do you want shortest time
routes, and return the distances for those? You can do the former by setting
all speeds in the `car.lua` profile to 3.6km/h, routes will then be calculated
as shortest distance, and returned "duration" values will be in meters.
- If you run your own OSRM server, you can set the maximum car speed in the
`car.lua` profile before pre-processing the data. You cannot set it on a
per-query basis.
Note that the API can return an `annotations` element, which tells you the
specific duration and distance of every segment of the returned route. If you
want to cap the speed, you could use this data to adjust the ETA in the
returned response using your speed limit to fix the returned durations. This
would be somewhat complex, but doable. Note that it would not *route* using a
maximum speed, but you could somewhat correct your ETA with this approach.
daniel
> On Jun 30, 2016, at 10:10 AM, Milton Garcia Borroto <[email protected]>
> wrote:
>
> Dear Daniel,
> Thank you very much for your promptly reply. We are using osrm for building a
> large distance matrix. Take a look for example to this calculation:
> Source: 8.512421667,76.97160333
> Destination: 8.538019178,76.96748103
> OSRM returns 3min 30 sec. If you check in travelmath, they return 10 minutes,
> which is more logical answer for a 5 km distance.
> Then I have some other questions:
> - Is there a way to get the distances instead of time?
> - Is there a way to select maximum car speed?
> Regards,
> Milton
>
> 2016-06-30 11:55 GMT-05:00 Daniel Patterson <[email protected]
> <mailto:[email protected]>>:
> Milton,
>
> What's the exact route in question? Start/end coordinates, or a link to
> map.project-osrm.org <http://map.project-osrm.org/> would help us figure out
> why it's marked as being so fast.
>
> daniel
>
>> On Jun 30, 2016, at 9:30 AM, Milton Garcia Borroto <[email protected]
>> <mailto:[email protected]>> wrote:
>>
>> Hi everybody,
>> I started using osrm few weeks ago, first the demo and now I am running it
>> in my own server. When using the distance matrix, I am obtaining very
>> different results from other services like TravelMath (www.travelmath.com
>> <http://www.travelmath.com/>). Taken a deeper look at the osrm results, I
>> note that you need to move really fast to attain the resultant times. For
>> example, a ride of 3.3 km is reported to be done in 3 minutes 30 seconds. Am
>> I doing or understanding something wront? Can I change the maximum speed?
>> Regards,
>> Milton
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