[OSRM-talk] Travel times too high

[Stefan Göckeritz]

Hey Rudi, 

nice mod, which actually really shows the issue. I spend the most of the
time driving at a speed of 72km/h, which is actually really not true.
You explained that in depth really well. 

Well, in Germany if there is no maxspeed (which is actually the case on
only some left over routes) recommended speed by law is 130km/h.
This calls for solution 1 that you came up with. Definitely +1! 

Solution 2 has one major issue (though it'd be a improvement to the
current state anyways), one is struggeling with empirical figures. There
will alsways be confusion whether this exact value is the one to stick
with. But as I Rudi said, at this specific case (3 lanes and maxspeed=0)
80% of 90km/h is way off reality, at least in Germany. 

So here is the question. Can this be implemented/altered in short term? 

Hope to be permanent user of OSRM very very soon... :- 

Keep up the good work.
Cheers 

 STEFAN GÖCKERITZ 
 Bachstraße 21
 53424 Remagen
 Tel: 0173/9335730 [6]
 EMail: admin at s-goecker.de 

Am 2014-05-19 23:02, schrieb Rudolf Mayer: 

> Hi Stefan!
> 
> On 2014-05-19 09:47, Stefan Göckeritz wrote:
> 
>> since some weeks I experience calculated travel times that are way higher than they are in reality. I use OSRM for quite some time now, but since the durations are not exact I use Google Maps, just because I need more exact travel times. For instance traveling from Berlin to Bonn takes 7 to 8 hours according to OSRM.at. Google Maps states something around 5 hours which is appropriate as I can say from my experience on this route. What is the deal with the time, they used to be not that exact, but since some time (I can't actually say since when) the calaculations are worse. Has there been a major change in computation or the car profile?
> 
> I noticed that also a few times, and there was a similar discussion 
> started by me, see 
> https://lists.openstreetmap.org/pipermail/osrm-talk/2014-March/000462.html [1]
> 
> Currently it seems that the car profile is currently asuming as default 
> value 90kmh for a motorway 
> (https://github.com/DennisOSRM/Project-OSRM/blob/master/profiles/car.lua [2])
> 
> From that speed, it seems only 80% are assumed as average driving time.
> 
> It seems that the profile does honour max_speed settings 
> (https://github.com/DennisOSRM/Project-OSRM/blob/master/profiles/car.lua#L173 [3]), 
> but it still means that e.g. for an Austrian motorway, 104 km/h (of 
> 130km/h) is the assumed average, and that seems just too low.
> 
> I guess assuming around 80% of average speed can be ok for 
> highways/roads that have only one lane, have crossings & lights, but for 
> motorways with 2+ lanes and without any level crossing, it seems just 
> too much.
> 
> For your specific route, my mod in the interface that also displays 
> travel time for each segment 
> (http://kronos.ifs.tuwien.ac.at/osrm/main.html?loc=52.517037,13.388849&loc=50.735849,7.101081 [4]) 
> shows that you spent a lot of time with this:
> 
> Continue onto A 2 411 km (5 h 38 min | 72.7 km/h)
> 
> So I guess the issue is
> - there's no maxspeed tagging (because you have no maxspeed for the 
> motorway in that section :-))
> => thus OSRM assumes speed to be 90km/h, from that it takes 80%
> => you get the 72km/h as average..
> (maybe the slightly higher value is from some portions where there is a 
> maxspeed set.)
> 
> And I assume in fact if the road is free you go double that speed...
> 
> So, I guess a few things that could be improved
> 
> - If maxspeed=<NIL>, and "in germany", assume something like at least 
> 130kmh.. That shouldn't be that difficult to achieve.
> 
> - rethink if 80% on a highway with status motor_way and/or lanes>=2 is 
> really appropriate. I'd assume something ~90-95% to be more reasonable 
> on a motorway.
> 
> Greetings
> Rudi
> 
> _______________________________________________
> OSRM-talk mailing list
> OSRM-talk at openstreetmap.org
> https://lists.openstreetmap.org/listinfo/osrm-talk [5]
 

Links:
------
[1]
https://lists.openstreetmap.org/pipermail/osrm-talk/2014-March/000462.html
[2]
https://github.com/DennisOSRM/Project-OSRM/blob/master/profiles/car.lua
[3]
https://github.com/DennisOSRM/Project-OSRM/blob/master/profiles/car.lua#L173
[4]
http://kronos.ifs.tuwien.ac.at/osrm/main.html?loc=52.517037,13.388849&loc=50.735849,7.101081
[5] https://lists.openstreetmap.org/listinfo/osrm-talk
[6] callto:02642/932-221
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