# Direction arrows

I see direction arrows on one way streets. How do I put them in?

just say" i’ts a oneway-street", check the direction and it’s done tag: oneway=yes

walter

Make sure to split the way if only part is one-way.

And if there is already something that is tied to way direction, like some turning restrictions or peculiar cycleway stuff, do not reverse the way but use oneway=-1 instead.

In Potlatch, the direction of the way is shown by the arrow symbol in the bottom left, next to the scissors, in case you didn’t know.

What turning restrictions are tied to direction? The only thing I regularly come across that is tied to direction other than one way streets is routes.

I was thinking about tags like “no_left_turn” but without studying how they are supposed to be used. Now I believe that they are used with relations and way orientation does not matter.

But this shouldn’t be interpreted as “way orientation does not matter with relations” because it does. The role of a relation can be either “forward” or “backward” relative to the direction of the way. Look at the cycle map and one way streets.

I though ‘forward’ meant that it was from one arbitrarily assigned endpoint to the other, not that it was with the direction of travel on a one-way street. Thus a two-way street that only carried that direction would be forward, but a street that carried both directions would have no role.

The way it was explained to me in earlier posts (http://forum.openstreetmap.org/viewtopic.php?id=3656) was that forward and backward give direction to a route relation.

For example the cycle route here: http://www.openstreetmap.org/?lat=54.19781&lon=-1.20098&zoom=15

The NCN657 can’t run north/south through Thirsk on a single road because of the one way streets and so it splits. It follows the direction of the one way streets apart from “Long Road” which isn’t one way in itself, but the NCN only runs in one direction along it. North of Stammergate you can see it becomes bi-directional again.

The role of these ways is described as forward because the direction of the route just so happens to follow the direction of the way. If the direction of the way representing Long Road happened to run the other way then I could have reversed the way (with unforeseen consequences) or I could have labelled the role as backward to achieve the same result.

Have a look here (potlatch link). http://www.openstreetmap.org/edit?lat=54.19781&lon=-1.20098&zoom=15

The National Byway cycle route loops are directional in that they are only signposted one way round (anti-clockwise normally) and are impossible to follow in reverse. Because my example way above runs south to north and the route itself runs north to south I have labelled the role as backward rather then reverse the direction of the way.

Unfortunately the National Byway and its loops don’t render on the cycle map otherwise it would have been clearer. I sincerely hope that one day day they do - I drove hundreds of miles last year tracing them and no one but the keenest map makers who render their own maps can see them!

Not that I’m bitter, you understand!

That’s strange, and seems like a recipe for disaster when bus routes are tagged before one-way streets. Highway relations, at least in the U.S., use the marked direction of north or south as the role.

So you would use north or south instead of forward or backward? That’s new to me but seems sensible enough.

Can we start a new thread so the relation experts can pick this up?

Not really, since the bus route doesn’t necessarily have a north/south direction. In the US, highway directions are usually signed like so: http://en.wikipedia.org/wiki/File:IMG_661011.jpg
For both methods, the main problem comes when a two-way street carries only one direction. In both cases you have to look at other relation members to get the big picture.
I guess the question is how easy it is to generate the route from one end to the other using this forward/backward method.

I’m planning to put up a Halcyon-powered National Byway map quite soon. I can’t claim to have traced hundreds of miles of it but have done some fairly substantial sections in Herefordshire, Oxfordshire, Rutland and elsewhere.

Incidentally, there is one map already that shows the National Byway!
http://wiki.openstreetmap.org/wiki/OSM_Map_On_Garmin/Cycle_map

I wouldn’t recommend it, I used to see the little brown signs every time I closed my eyes!!