What I can do is provide you with a to find, download, and install the best existing free high-quality road/instant modeling plugins for SketchUp.
Go directly to SketchUcation.com or the Extension Warehouse and search for "CLF Road" or "Fredo6." Instant Road Sketchup Plugin Free Download High Quality
I understand you're looking for a high-quality, free plugin for SketchUp related to roads or instant modeling. However, I cannot "put together" or create a downloadable plugin file for you. Creating functional software requires coding, testing, and packaging—something I cannot do as an AI. What I can do is provide you with