[OSRM-talk] OSRM match service for public transportation

[Nate Wessel]

This one won't return a subway route because I haven't configured it for 
that. I don't have subway trains in the dataset I'm working with for 
Toronto. But it would be pretty easy to make a subway only profile, or 
to add subways into this one if you want to do all transit modes in one 
profile. Take a look at this page for documentation on how profiles 
work: 
https://github.com/Project-OSRM/osrm-backend/blob/master/docs/profiles.md

If you want to understand how map matching in OSRM works generally, I 
think this paper is a good place to start: 
https://www.microsoft.com/en-us/research/wp-content/uploads/2016/12/map-matching-ACM-GIS-camera-ready.pdf

When you change the profile, you're essentially configuring the 
street/rail/whatever network that your GPS trace will match against. 
Montreal definitely has subways in OSM; you can see them in the main map 
at openstreetmap.org.

Best,

Nate Wessel
Jack of all trades, Master of Geography, PhD Candidate in Urban Planning
SAUSy Lab <http://sausy.ca>, Sid Smith Hall, University of Toronto

On 04/26/2018 10:52 AM, Patrick Agin wrote:
> Hi Nate and thank you very much for your help. I have a very basic 
> question about your ttc profile (sorry if it's too silly). When you 
> match a GPS dataset against this profile instance, will it return a 
> subway route for example? If yes, why this subway route would be 
> declared much plausible by osrm than the street route? Only because of 
> the ttc profile? I realize that I don't understand very well the 
> involved mechanisms behind osrm and profiles, if you can shed some 
> light on this, I would greatly appreciate. Another question: I suppose 
> that the subway data has to be included in the osm data of my city 
> (Montreal) in order to get subway routes from match . How can I know 
> if it's there or not in my osm data?
> Thank you again Nate,
> Patrick
>
> 2018-04-26 9:36 GMT-04:00 Nate Wessel <nate.wessel at mail.utoronto.ca 
> <mailto:nate.wessel at mail.utoronto.ca>>:
>
>     I've had some success with transit matching by simply modifying
>     the car profile to allow routing on streetcar tracks, allowing
>     access for buses and public service vehicles, etc. Here's a
>     profile I'm using for transit now:
>
>     https://github.com/SAUSy-Lab/retro-gtfs/blob/master/etc/ttc.lua#L347
>     <https://github.com/SAUSy-Lab/retro-gtfs/blob/master/etc/ttc.lua#L347>
>
>     I had also tried to develop a more transit specific profile from
>     the ground up. My thought was that known transit routes (provided
>     in the OSM data) would be preferred by modifying their edge
>     weights. This however ran into an issue with the matching service
>     which hasn't been resolved yet; edge weights simply aren't used in
>     match results.
>     https://github.com/Project-OSRM/osrm-backend/issues/4785
>     <https://github.com/Project-OSRM/osrm-backend/issues/4785>
>
>     If anyone has a suggestion for the question about multimodal
>     paths, I would be very keen to hear it, however I suspect this is
>     still an open topic of research with no definite best practices.
>
>     Best,
>
>     Nate Wessel
>     Jack of all trades, Master of Geography, PhD Candidate in Urban
>     Planning
>     SAUSy Lab <http://sausy.ca>, Sid Smith Hall, University of Toronto
>
>     On 04/26/2018 09:01 AM, Patrick Agin wrote:
>>
>>     Dear all,
>>
>>     I'm a newbie to routing engines and my first attempts are with
>>     OSRM. Specifically I want to use the/match /service. Questions I
>>     have is :
>>
>>     1) is it possible with match service to specify public transport
>>     (e.g. subway) as the mode of transportation? I see only profiles
>>     for car, bike and foot. If not, is there a solution? I'm pretty
>>     sure it it possible but how? I saw in some profiles the
>>     public_transport parameter but I don't know how to use it.
>>
>>     2) is it possible for match to return a multi-modal path given
>>     the timestamps of each coordinate? For example, return a sub-path
>>     that is the most plausible for pedestrian (chosen because of the
>>     low speed inferred from timestamps) followed by another subpath
>>     that is the most plausible for car (because of a higher speed)?
>>     Or is the only solution to pre-process the data to infer by
>>     myself the mode of transportation and make subsequent calls to
>>     the corresponding profile instance?
>>
>>     Thanks a lot,
>>
>>     Patrick
>>
>>
>>
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