What characterizes a decreasing radius curve?

A decreasing radius curve is characterized by a sharp curve that becomes tighter as the driver progresses through the turn. This means that as the vehicle enters the curve, the radius of the turn decreases, requiring the driver to make sharper steering adjustments and potentially reducing their speed to maintain control. Such curves can be particularly challenging, as they may catch drivers off guard if they are not prepared for the increasing tightness of the turn.

A constant radius does not fit this definition, as it implies that the curvature remains the same throughout, which is not the case for a decreasing radius. A long and gentle curve refers to a much more gradual change in direction, lacking the sharpness associated with decreasing radius curves. Finally, a curve that allows for higher speeds throughout suggests a more uniform and consistent radius, which does not align with the characteristics of a decreasing radius curve, where control and speed management become crucial due to its tightening nature.