Key:duration

Used to indicate duration of a route that is bus, route=ferry, railway=funicular, aerialway=cable_car etc. The duration does not include any possibly required waiting time. Applied to relations or ways. The duration for a relation should contain the sum of durations needed for the individual relation elements.

Most useful where the route has a clear beginning and end. Should only be applied where normal routing algorithms and traffic analysis cannot figure out how long it takes (highways is the most obvious example).

It's uncertain how to show duration between stops. Comments are welcome.

Related tags are aerialway:duration=* for aerialways, and maxstay=* for parking.

Values

The recommended format is the simple 'hh:mm' format for hours and minutes. OSRM or GraphHopper support either 'mm', 'hh:mm', or 'hh:mm:ss'.

Be aware that values less than one hour have been entered as simple integer minutes. This practice is discouraged as it's ambiguous with integer hours.

A few very long routes' durations are expressed in ISO 8601 format, but this may be unnecessary because the duration of even the longest ferry route, 672506453 672506453, may be expressed conventionally in hh:mm format.

That being said, it is already 3-digit. From the other end of the spectrum, this time period format may be confused with MM:SS with potential use in tags such as interval=*. Outside transportation, other features such as maxstay=* (and theoretically a minstay=*) on parking, hotels, and other facilities will need to be described by longer time periods, which is using full form unit as "approved" in Proposed features/Maximum Stay.