I made a part of a bridge and copy pasted it to it´s designated length.
No i have many lines witch aren´t needed(the blue ones in my picture). Is there a possibility of getting rid of them or do i have to do it one by one?
Hey again 
you could use Selection Toys extension. Then right click one line and do delete all similar (under Selection Toys in the right click menu)
Hi
You mean this one?
Can´t find “delete all similar”
Yeah that’s the right one. Right click one of the lines, go under ‘selection toys’ and click select all similar. Then just push delete (on your keyboard)
No select similar
Under “select”
Not select only
There may have been a smarter way to model than copying the sections. For example, you might have just used Push/Pull to extrude the roadway and then copied just the legs etc.
Alternatively, you could have gone into the group and hidden the ends. the lines wouldn’t get deleted but they would get hidden.
Just hide them. Drag over them with the eraser while holding shift. If you don’t need the lines at all then delete them. There’s no reason to use extensions that I can imagine.
That´s it!
Work quite good
For a duplicated structure such as this you should use components, not groups or loose edges and faces. Then you could open just one instance for edit, hide the border edges, and all the copies would be fixed at one go.