How does heavy rain typically affect highway traffic?

Heavy rain has a significant impact on highway traffic, primarily by reducing vehicle speed and visibility. When rain falls, it typically creates a wet surface that can lead to hydroplaning, where tires lose traction with the road. This situation prompts drivers to decrease their speeds to maintain control and ensure safety, thus leading to an overall reduction in traffic speed.

Furthermore, heavy rain can limit visibility due to the accumulation of water on windshields, causing drivers to struggle to see clearly ahead. Reduced visibility can also make it more challenging to notice road signs, other vehicles, and potential hazards, therefore increasing the cautiousness of drivers who may opt to slow down further to navigate safely.

The interplay of these factors creates a scenario where traffic flow is often impeded during heavy rainfall, affecting not just individual driver behavior but also overall traffic patterns.