I see a difference in testing but maybe the setup is good for it (if your camera sees the entire road it won’t cull anything using offscreen).
Otherwise the only thing that crossed my mind is to cut the road up into chunks (or by doing selection sets) and adding a Hair Object to each chunk then use Xpresso to Enable them depending on the distance from the camera. Combine that with Offscreen culling (to not render the one’s you’ve gone by). Depends on the setup, how much of the road we see at any one time.