There are three categories of road line marking. A surface mark can be mechanical, temporary, or non-mechanical. Mechanical devices used for marking surface marks can be sunk into the surface of the road, or they can be raised above its surface. These devices can be permanent or movable and are either reflective or non-reflective.

Here is an in-depth look at some of these devices, especially for trainee road contractors.

Botts' Dots

Botts' dots are raised road surface markings named after the engineer credited with the invention of the epoxy used to glue down the dots. Botts' dots are non-reflective surface markings. As such, they are commonly used alongside raised reflective markers for enhanced visibility.

On the road, a Botts' dot will appear as a low rounded white dot and will often be used across travel lanes. The dots draw the attention of the driver to the road, thereby reducing the likelihood that he or she will cause an accident.

Botts' dots will commonly be used to inform drivers that they're getting into a school zone, or to indicate the presence of a toll booth both of which require the driver to slow down.

Botts' dots are most suitable for use in warm climate areas with little snow. When used in areas with heavy snow, the dots are often removed alongside the snow when the snow plow is making rounds.

The Cat's Eye

Cat's eyes are perhaps the most commonly used mechanical road surface markings. The cat's eye is a reflective marking made up of four lenses and a rubber housing. Two of these lenses are mounted on the front of the rubber housing while the other two are mounted on its rear. The rubber housing is then mounted inside a shoe made of cast iron. When a motorist drives over the rubber housing, it sinks into the iron shoe. Cat's eyes are suitable for use in areas with heavy snow because their sinking ability protects them from the damaging effects of snow ploughing.

Rumble Strips

Rumble strips can be raised or recessed into the road surface. Recessed rumble strips are often made of several troughs (with a width of between one and ten centimetres) that are ground from the asphalt surface of the road. Raised rumble strips are made of raised strips that are either glued or painted onto the road surface.

Rumble strips are commonly used across the driver's direction of travel as a warning sign of hazards that lay ahead. They may also be used along the driver's travel direction to indicate hazards associated with the drivers not maintaining their lanes.