Central hatching (painted medians) and wide centrelines increase the separation between traffic travelling in opposite directions on undivided roads. This reduces the risk of head-on crashes. In addition, central hatching can be used to narrow wide lanes and therefore encourage lower speeds.

Central hatching may be used in both rural and urban areas. In urban areas, it provides some protection to pedestrians crossing the road, and may be coupled with pedestrian crossing facilities, such as refuge islands to provide added security.

If the hatching is wide enough, it can contain a turn lane. Where road rules permit driving on painted hatching, it is often used as an informal turn lane.

In rural areas central hatching and wide centrelines can be used with rumble strips or pavement markers to alert drivers when they are leaving their lane.

Central hatching and wide centrelines can be installed over a continuous length of road or at specific points – for example, curves and crests in the road.