How to identify the direction of travel for ways without "oneway" tag

Question

I am using Overpass API to download ways and nodes information for my application and I have realized that not all the ways have information related to the direction of travel.

How can I identify if the way supports direction in both sides/with line direction or against direction when no tags are attached?

Example url: https://lz4.overpass-api.de/api/interpreter?data=[out:json];way(50.05288170227778,8.69143545627594,50.05597466228186,8.694798946380615);out%20meta;

Answer 1

The direction of travel depends on the presence (and the specific value!) of the oneway tag. If there is no oneway tag present then the road is bidirectional, except for other tags implicating oneway=yes such as:

• highway=motorway or highway=motorway_link
• junction=roundabout

If neither a oneway tag nor any of the other mentioned tags is present then the traffic is bidirectional, i.e. oneway=no.