Here in Brisbane, asphalt is the most common material used for roads and large carparks. This is the black, rocky substance that you will probably see as soon as you step onto your street.

You may have heard that roads are made from bitumen. This is not strictly true, although it is close enough for a layperson’s understanding. Bitumen is a by-product of refining oil, and is not used alone in paving roads. Rather, it is mixed with other substances to create asphalt. The other substances in the mixture are usually pebbles and sand. This results in a bumpier surface than using bitumen alone, creating more friction for vehicles that drive across the road.

Friction is generally thought of as bad by drivers, as a surface with friction requires more force to travel across, therefore increasing use of fuel. However, friction is essential to road surfaces. With absolutely no friction, a car would not even be able to move across a flat road surface at all. As you add more friction, the stopping distance of a car in motion decreases. Therefore a surface providing plenty of friction is safest for road users, who are able to stop quickly as many potentially dangerous situations require. While friction is good, excess bumps are not. An unexpected pothole on the road can damage the vehicle travelling over it, and may cause the car to move in a direction not anticipated by the driver. It is also uncomfortable for passengers to travel over an excessively bumpy road. For these reasons, it is important that any cracks or faults in asphalt are repaired before they develop into holes.

There you have it,  a quick overview of asphalt roads and asphalt car parks, Brisbane was used as an example here however this information is true of many cities throughout the world.