I’ve started using JOSM and hit an error. I am trying to combine two ways which are currently showing as two separate streets but are in fact the same street. One of them has arrows pointing from left to right when I select it, and the other has arrows pointing from right to left. What do these arrows indicate, because when I try to combine these two ways I get an error:
“The ways can not be combined in their current directions. Do you want to reverse some of them?”
Do the arrows indicate one-way streets, or something? If so, these streets have been incorrectly defined and I need to change them to be two-way streets.
The arrows just indicate the direction that the mapper mapped them i think.
If it is the one street with the same properties then just reverse and combine. Check the tags on each section first though.
If you needed to make part of a road oneway it is best to get the arrows pointing in the direction of vehicular travel first before adding the oneway=yes tag. There is a menu item to reverse a way so you could select one part and reverse it and then combine if you prefer.
Also some other tags are direction-dependent, but JOSM wil show another warning for most of them.
But concatenating two ways is something rarely needed, which can easily destroy data. For example if there are relations involved or different tags. In the case shown above there is no need to combine the ways.
Thanks for the responses. I’d like to understand this better so I don’t destroy any valid data. In the example I was showing I believe the two ways had the same tags and are actually the same road. They are the same surface, the same speed, the same two-way. If that’s the case they should be combined, shouldn’t they? What was it about them that made you think they shouldn’t be combined?
I’ve actually found a lot of ways on the OSM maps for my neighbourhood which are defined as two ways but is in fact the same road with the same attributes. There’s usually a junction, or sharp bend involved. I think my neighbourhood has some raw mapping data which hasn’t been tidied up or tagged very much at all.
Well, there is no real need to combine two ways if they have identical tags and are connected, because all programs using OSM data should cope with those elements.
Because on the other hand, each edit to an OSM object produces a new version of it in the main OSM database. So you don’t save digital place in real. Deleted objects remain in that database, they only get a flag to make them being deleted.
Also some short ways are better to handle rather than really long ways, when you are inside one of the OSM editors.
If you can show us a concrete example (via permalink) where you think that segmenting is too much, we can inspect and maybe give an opinion.
There’s two reasons I can think of why to combine them anyway.
For rendering: if a street is split up, all pieces get rendered with their name. In a lot of Peruvian imported town every block is a separate way, which makes for ugly and confusing rendering.
For searching: every bit of the street will be a hit when you search for it. Only the picked result will be shown as a hit. So the searcher might think he found a short street, while the street in fact is very long.
So, I wouldn’t spend my time joining streets together. But I wouldn’t split up streets unless necessary.
That is a good attitude but not always what happens in practice. Imagine a mapper driving on a very long street and making a turn half way. This mapper can add an attribute to this part of the way (for example surface=asphalt) but in order to do this he has to cut the way into 2. The next day the same happens to another mapper coming from the other end of the street taking the same turn. He also adds the surface=asphalt to this part of the street. We then end up with 2 parts with exactly the same tags. Ways get split because we map on our tour/drive and not necessarily because the attributes of the parts are different. In this case I would encourage combining the ways.
This also has the advantages for rendering en searching as you mentioned.
I’m not sure if it’s the right place to ask this (1st time here).
The point is that i have the streets already created but, when it’s time to tag their names sometimes this “stret” has two names.
Allow me to be more especific; For example, two blocks is “whatever st. name” and there is an intersection but the same street continues with a different name.
You know what I mean? (sorry about my english).
I would like to tag different names on a street that it has been created before. How can I do that? Do I need to create again the street, modify it (how)? Can I split somehow this one?