Started on OSM: 30 June 2008
Route relation & Split routes
This section is about clarifying the forward/backward role in route relations. While this is also used in cycle node network tagging, its scope is wider, since this touches on all type=route relations.
A split route is a route where different paths are followed depending on the direction the route is followed. Examples of this would be oneway roads, or access restrictions.
The route relation for this should use proper forward/backward roles. These roles tell the direction that a way can be travelled, with respect to the direction of the way as it exists in the OSM database. This could be different than the direction you're taking that road in real life.
In the above example, the route splits up in 2 separate ways, due to these being oneway. A more complex example, where you have to follow different routes, but which aren't necessarily all drawn in the same direction: