Subpaving is like building a secret base deep underground. Just like how you build a sandcastle by digging deep into the sand, subpaving is the process of creating a strong foundation for a road or a building.
First, workers dig a very deep hole in the ground. This is like digging your sandcastle really deep into the sand. Then, they put some things into the hole to create a strong base. These things can include tiny stones, sand, gravel or even concrete.
Once the base is strong and stable, they cover it up with a smooth layer of material, usually concrete or asphalt. This is like putting the top layer on your sandcastle to make it look pretty.
The subpaving ensures that whatever's built on it is strong, stable, and lasts for a very long time. And just like your sandcastle won't fall down if you build a strong base, subpaving helps make sure that buildings and roads don't fall apart too!