[OSM-talk] Re: One way streets

[Simon Hewison]

David Groom wrote:
> There would seem to be two possibilities for marking one way streets.
>  
> 1)  One is to mark all the segments of that street as oneway=yes
>  
> 2)  The other is to mark the way as oneway=yes
>  
> option (1) has the advantage that it can cope with the fact that some 
> parts of the same street might be one way and others might not
>  
> option (2) has the advantage that it would be a lot quicker to add the 
> key value pair to one way, rather than to all the segments which 
> constitute the way.  In this instance if part of the same street is one 
> way and part is not then you would I assume have to create two separate ways
>  
> I note in the online applet that the "oneway" check box only applies to 
> ways and not segments.
>  
> What is the general recommendation?

That keys/value pairs on a segment override what's defined on the way.
That's how it should be, and how any routing algorithm should deal with it.
So, you don't go tediously defining oneway=yes on each and every segment 
of motorway, but if you need to, you can have a way that is normally one 
way, but has a small section of two way traffic by defining oneway=no on 
those segments.

didn't someone come up with the idea of oneway=-1 to denote it's a 
one-way street, but in the opposite direction to the line segment, maybe 
this is needed after all in some cases.

--
Simon Hewison