Lets see 3 miles of road at minimum 24' wide that would be 380,160 Sqft and assume they pave it with 4" asphalt depth. That would be about +$4.80 a sqft. that is $1,824,768 to pave. that is just the cost of the asphalt.
Then add the preparation of the base, mobilization fees, water fees, environmental fees, you are looking at $5 million of work!
This is just off the top of my head, could be more could be less.