Public Transport Workshop

There are many questions around mapping public transport related things in OSM. Should stops be tagged on the traffic way (like the highway or railway) or next to it (say where the bus stop sign stands)? How can you tie together several platforms of one railway station? What is the relationship between a subway line, the platform where it stops and the subway entrance? How should bus lines or subway lines be tagged and what about different variants of the same line? There are many more questions like this. Upon invitation from Geofabrik some people from the German OpenStreetMap community met in Karlsruhe on May 16th 2009 to discuss these issues and make some progress. Twelve people attended this meeting, including Melchior Moos, the creator of the OSM public transport slippy map at www.öpnvkarte.de and Thomas Reincke from the public transport authority of Aachen. Of course Frederik Ramm and me were also present.

Sebastian Schwarz, a student at the Karlsruhe University of Applied Sciences, is currently doing his diploma thesis with Geofabrik on this topic. He looked into previous discussions in the OSM community as well as how other organisations have been modelling public transport data. In this workshop he presented his findings and his ideas for improvements. The discussion then ranged over many topics and I think we found good solutions for many problems. Of course many compromises needed to be done and the ideas we came up with are not the end of the discussion but just one further step. We had to keep current practice in mind and tried to make things as simple as possible but still allow the complex material to be tagged in a way useful for renderers and other uses of the data.

The main topics were:

• Clear differentiation between infrastructure (the actual “hardware” like the rail tracks itself or the stops) and network information (like bus lines and subway lines) relating to this infrastructure
• More consistent tagging of different types of transport (Why is it “halt” for trains but “bus_stop” for buses? Why is one placed usually on the rail itself, the other next to the street?)
• Introduction of a new “public_transport” tag key
• Clustering of stops into “stop areas” and “stop area groups” to model large train stations etc.
• Clear differentiation between “stop positions” (where the vehicle stops), platforms (where people wait and enter the vehicles) and entrances (for instance for subways)
• Differentiation between railway routes describing longer stretches of possibly named railways and the public transport lines using those railways

Much more detail is available on the following Wiki pages:

• http://wiki.openstreetmap.org/wiki/User:Oxomoa/Public_transport_schema (in English)
• http://wiki.openstreetmap.org/wiki/User:Oxomoa/ÖPNV-Schema (in German)

Once the information has stabilized somewhat we’ll move those pages to a more “official” location.

Feel free to leave comments on the talk pages. Or discuss on the transit mailing list.

Sebastian has also worked on the OSM Inspector and added five new views that show different aspects of public transport mapping in OSM:

• Railway Infrastructure – Shows the different types of rails
• Non-railway Infrastructure – All non-rail infrastructure such as bus guideways, escalators or taxis stands
• Ferries – Shows ferry lines and terminals
• Stops – Shows all kinds of stops including stop position, accesses (such as platforms) and stop areas
• Network – Shows public transport lines

Suggestions on how to improve those views are welcome.