Which of these is often a reason for traffic congestion?

Traffic congestion is often exacerbated by accidents because they can significantly disrupt the flow of vehicles on the roads. When an accident occurs, it can lead to lane closures or reduced speed limits, forcing drivers to slow down or stop altogether. This creates a bottleneck effect, where the number of vehicles merging into a smaller space increases, resulting in further delays and a build-up of traffic behind the incident.

While vehicle breakdowns can also contribute to congestion, they typically occur less frequently than accidents and often involve isolated incidents where only a single vehicle is affected. Large events can cause temporary spikes in traffic, but they do not present the same immediate disruption as accidents. High-speed internet is not relevant to traffic congestion as it pertains to digital communication and connectivity rather than physical road usage. Thus, accidents represent a key and direct cause of traffic congestion.