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.
The Cost of DIY Gravel Driveway Construction. A gravel driveway is a great way for a homeowner to be able to do lay their own driveway and keep their costs relatively low. Unlike an asphalt or cement driveway, a homeowner can complete this task without having to purchase or rent heavy equipment, and the materials are, on the large part, cheaper.