You need a "TIN" (Triangulated Irregular Network).
: Available for download on the SketchUp Extension Warehouse . However, it has significant limitations: instant road plugin sketchup free download
Creating realistic roads on uneven terrain is one of the most frustrating tasks in 3D modeling. Manual draping and stitching often lead to jagged geometry and countless hours of cleanup. The Instant Road plugin by Vali Architects You need a "TIN" (Triangulated Irregular Network)