[OSRM-talk] OSRM match service for public transportation

[Patrick Agin]

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>:

> 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
>
> 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
>
> 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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