It is often the case that the coordinates of stops are relatively far away from where the passengers are expected to the wait for the vehicle.
A good example of this is Buckhead subway station in Atlanta.
There the coordinates of the stop in GTFS are located near Peachtree Road so OTP would instruct passengers to wait on the street rather than walking down the stairs to the platform.
We can correct the waiting location for the passenger by adding some tags to OSM which help OTP decide to correct the location. In general, you should familiarise yourself with the OSM wiki page on public transport.
You can add cross-references to a stop's id or code on all OSM entities (nodes, ways, relations) which have one of the following tag combinations:
railway=stopare explicitly not on the list as they denote the place where the train stops, not the waiting area.
railwaykey is deprecated (even though still widespread) and you should use
In order to tell OTP how to link up the OSM entities to the stops you need to add a
ref tag whose
value is the stop's id or code.
However, tagging conventions vary from location to location so other tags can be configured, too.
Multiple stops on the same platform
Some stations have a middle platform with a stop on either side of it. In such a case, you can simply add two or more references separated by a semicolon, as seen in this example.