[OSRM-talk] Huge difference in needed time computation OSRM / Google Maps

[Philip Barnes]

The lack of speed limits on the rural secondary roads will almost
certainly be having an effect here.

If you are in the area, it would be a good idea to survey and tag the
speed limits. I have found that correct speed limit tagging will often
fix these problems.

I find a dashcam/video camera mounted in the car helps, as it is
difficult to remember exactly where the change of limits occurs.

Phil (trigpoint)


On Mon, 2014-03-24 at 14:34 +0100, Rudolf Mayer wrote:
> Hi!
> 
> [Dennis Luxen], On 2014-03-24 14:01:
> >> http://osrm.at/?hl=en&loc=48.208845,16.372329&loc=48.276104,16.791565
> >
> > ...
> >
> >> This seems very wrong, though, Google maps estimates (http://goo.gl/maps/EPt14)
> >> a.) a likely more optimal route, preferring bigger streets
> >> b.) estimates 45,1 km, 47 Minutes. Almsot 30 mins difference in a 47 minutes route seems way off…
> >
> > We do not have any real traffic info, especially no information on how long routes actually takes. Thus we have to make educated guesses. Unfortunately, these guesses may sometimes be off. If we just had an army of cell phones telling us their positions every other minute. ;-)
> 
> 
> I understand that perfectly ;-)
> 
> but the given difference just seemed way too much, as the OSRM route 
> takes >50% longer.
> 
> >> I am not sure what this is caused by, the map data seems ok for this route.
> >
> > Did you spot any portions of the route that take obviously too long?
> 
> 
> A better link than before, to be more comparable to google:
> http://osrm.at/?hl=en&loc=48.209198,16.372941&loc=48.276104,16.791565
> 
> Now when I put that on my version of the interface at
> http://kronos.ifs.tuwien.ac.at/osrm/main.html?hl=en&loc=48.209198,16.372941&loc=48.276104,16.791565 
> to get the segment details, the following estimates seem to take likely 
> too long:
> 
> * Turn slight right onto L2
> 5.54 km (9 min | 35.5 km/h)
> 
> * Turn right onto L2
> 7.81 km (13 min | 35 km/h
> 
> These are secondary roads, partly in villages with 50km/h speed limit 
> (but not much traffic 90% of the time, as there are no traffic lights or 
> major intersections), but for the rest the limit would be 100km/h, and 
> occasionally 70km/h before crossings. thus the average of 35km/h seems 
> very much off, and I would rather expect double that speed.
> 
> >> Besides this huge time difference, one particullarily interesting detail in the routing is at http://osrm.at/6PV, where OSRM prefers a short cut through a much smaller street (tertiary vs primary) that has much more crossings, and http://osrm.at/6PW would be the much preferred rout..
> >>
> >> Any ideas why this is happening?
> >
> > Both routes have a very similar estimated driving time with the „bad“ one just a bit faster. Turn penalties, ie. caring for turns and passed intersections is on the roadmap.
> 
> 
> Do you consider the lane information as well? I see that on the priority 
> road this wasn't provided correctly everywhere, I fixed that now, maybe 
> it will change after the next update.
> 
> thanks,
> rudi
> 
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