What specific area next to the road is made clear and flat so a car that leaves the road can stop safely?

The specific area next to the road that is made clear and flat so a car that leaves the road can stop safely is known as a clear zone. A clear zone is an unobstructed, relatively flat area that extends outward from the edge of the traveled way, which is the main part of the road used for driving, including any paved or unpaved shoulder. Its essential purpose is to offer a driver whose vehicle has left the road, known as an errant driver, a safe space to recover control, slow down, or stop without hitting a severe obstacle. To achieve this safety, the clear zone is kept free of rigid objects like large trees, utility poles, bridge supports, or non-frangible signposts, which are signs that do not break away upon impact. If objects must be present, they are designed to be "crashworthy," meaning they are engineered to minimize harm upon impact, such as using breakaway supports for smaller signs. Additionally, the ground within this zone is made "traversable," meaning it has gentle slopes and shallow ditches that a vehicle can safely drive across without rolling over or experiencing a severe crash. The required width of this clear zone is specifically calculated during road design based on the road's design speed, which is the maximum safe speed for which the highway was planned, the volume of traffic it carries, and its horizontal alignment, referring to the straight and curved sections of the road.