What characteristic defines longest safe curves in roadway design?

The longest safe curves in roadway design are characterized by longer curves being safer than tighter ones. This principle is based on the physics of vehicle dynamics and human factors in driving. Longer curves provide drivers with a more gradual change in direction, allowing for better control of the vehicle and enhancing comfort. These curves reduce the risk of skidding and allow drivers to make adjustments to their speed and steering more smoothly compared to tighter curves, which require sharper steering maneuvers and may lead to loss of control if approached too quickly.

In essence, longer curves accommodate a wider range of vehicle speeds and driver reactions, contributing to overall road safety. The concept of designing safer curves is grounded in the understanding that human drivers benefit from predictable and manageable road geometry, resulting in a decreased likelihood of accidents and improved traffic flow.