You can create alleys / rows from any AREAL3D element (context menue).
The elements have a default distance, but it can always be overwritten in the VCB or selected from the comtext menu.
Simply place STARTPOINT and ENDPOINT somewhere in the viewport and the alley will be generated on the mesh/face crossed by the virtual line between stert/end..
Again on some materials like streets no elements will be placed.
Hold ALT with the startpoint to become an unregular distance between the elements (randomized).
Available basic elements
- trees
- streetlights
- post
- sphere
Context menu:

Normaly the latest created row remains selected, so that the user can easily correct its direction (>> sketchup>rotate).
Use the adapt function then to align to terrain in the new position.
You can switch easily to the Tree-tool from the context menu.