Snap to centerline of plane

I tried to make simple game where player object would travel to given destination in navmesh.

I use unity plane objects to denote “roads” which on player can move. Everything else works but I would like to snap target object (position determined by mouse click) to center line of road plane. I coudn’t find a way to extract global space coordinates from plane object.

I don’t have any grid in my game, so roads can be arbitrary placed. Currently only horizontal and vertical but plan is to have diagonals as well.

How I can achieve snapping?

You could always use the center of the plane by using transform.renderer.bounds.center