In which conditions should a driver significantly reduce their speed by 20-50 percent?

Reducing speed by 20-50 percent is crucial during adverse weather conditions like ice, snow, fog, and rain. These conditions can severely impact visibility and road traction, increasing the likelihood of accidents. For instance, icy or snowy roads reduce tire traction, making it difficult to stop or steer effectively, leading to longer stopping distances. Fog significantly diminishes visibility, making it harder to see other vehicles and road signs. Rain can create slippery surfaces and further reduce traction, which can lead to hydroplaning. Therefore, adjusting speed in these scenarios is essential for maintaining control of the vehicle and ensuring safety for both the driver and others on the road.

While heavy traffic and residential areas also require caution and often reduced speeds, the extreme conditions presented by ice, snow, fog, and rain necessitate a much more substantial reduction in speed to navigate safely. Expressways, on the other hand, typically have higher speed limits that are not safe to adhere to under the described adverse conditions.