guys one node can be shared by two ways ?

As far as i know, one node can have many tags, one way can have many tags and many nodes… but i don’t really know if one node can be shared by several way’s ?

Yes. For example if you have a road junction. The junction-node is shared by both roads.

Sure, on every junction all ways share one node.

thanks a lot for your replys.
downloading osm file an will import it to analyse better the structure :smiley: