[OSM-talk] How to tag oneway exceptions?

[Tobias Knerr]

Ben Laenen wrote:
>> The proposal "Conditions for access tags" allows to alternatively use
>> oneway=yes + oneway:bicycle=no
>> which is a bit more flexible because it is not limited to bicycles,
>> see
>> http://wiki.openstreetmap.org/wiki/Proposed_features/Conditions_for_a
>> ccess_tags
> 
> But bicycle:oneway=no is much more logical of course since you're 
> defining the access rights of bicycles...

Have you read the proposal as well as the "Extended conditions for
access tags" add-on proposal? Your argument would be valid if the only
possible "condition" would be the type of vehicle. However, it's also
possible to use current time, weather, lighting etc. as a condition.

As most conditional access tags do not contain a vehicle class, the idea
of "defining the access rights of vehicle class x" cannot apply to them.
Instead, condition semantics are used: The base key (the first part of
the key) applies if and only if all appended conditions are fulfilled in
the situation at hand. So the way is normally an oneway street, but for
people using a bicycle it isn't.

This makes sense for other conditions than vehicle classes, too, and can
be easily and logically extended to more than one condition (for
example, maxspeed:hgv:wet for hgv maxspeed on wet roads).

> The xxx:oneway looks to be used a lot more often than oneway:xxx as well 
> in current data

I haven't seen a consistent definition using your way of tagging that
works for more complex cases with multiple and non-vehicle conditions,
though.

Tobias Knerr