What does the term "overcapacity" refer to in terms of driving?

The term "overcapacity" specifically refers to a situation where the number of vehicles on the road surpasses the road's designed capacity, leading to traffic congestion. When this occurs, vehicles may experience slower speeds, longer travel times, and increased likelihood of accidents. High traffic volumes can create a bottleneck effect, where the demand for road space exceeds the available supply, resulting in a scenario where even the simplest movements—like merging or turning—become difficult.

The other options discuss different aspects of driving and traffic management but do not align with the definition of overcapacity. For example, parking issues pertain to where vehicles are stored rather than their movement on the road. A vehicle breakdown and malfunctioning traffic lights could contribute to traffic problems but do not represent the broader concept of overcapacity on a road network itself. Thus, the focus on the number of vehicles in relation to road capacity distinctly captures the essence of what overcapacity entails in driving contexts.