Models however, also have limitations. The model used for electric circuits by scientists today makes use of the idea that all substances contain electrically charged particles (see the focus idea Macroscopic versus microscopic properties).
Depending on the materials used, a driveway can be utilitarian, like gravel, asphalt, or concrete, or decorative, like stamped asphalt, stamped concrete, or cobblestone. Typical costs: A gravel driveway starts at roughly $0.75-$3 or more a square foot, or $300-$1,000 for a 12'x25' single-car driveway. Costs can double for a roadway-quality driveway. Loose gravel will need replenishing periodically, but a correctly designed, installed and maintained gravel driveway can last 50-100 years or more.
1 Total driveway paving cost will vary from region to region consistent with local material and labor costs. 2  Most gravel driveways are made of crushed stone or gravel which costs about $25-$30 per ton plus $100 or so for delivery per load (the average dump truck can handle 13 or so tons.) For a small, 15 ft. Asphalt driveway paving costs $2-$6 per square foot installed. 2  For a 500 square foot (50 x 10) driveway this works out to an average cost of $2500. 3  A Macadam driveway, also known as tar and chip, consist of crushed stone or gravel sprayed with liquid asphalt.