[RFC] Feature Proposal - One-way for pedestrians

[Langlaeufer]

@drolbr

. Afterwards, a pedestrian router can safely follow the rule:

• if highway=footway is set and bicycle is absent then process it as a oneway for pedestrians
• ignore the oneway for pedestrians in all other cases of highway=footway

This is NOT SAFELY. This is only a heuristic that routers can use.