[bubbacluck]

They’re rebuilding the 5 through town here and use those things. They are also laying down asphalt as a base and then concrete with rebar on top of that. It’s taking forever but may be worth it.

[philman_36]

They are also laying down asphalt as a base...

A protective barrier. Much better than just oil. Too much water on the layer underneath is not good. That under layer will make or break a road. Ask the Romans...

...but may be worth it.
Probably will. That much traffic needs a thick concrete layer. Stop and measure it...you're helping to pay for it. Should be at least 10".