Final answer:
Light rain causes oil and gasoline on road surfaces to create a slippery layer, decreasing vehicle control due to lowered friction, while heavy rain can wash these substances away but also increases risk of hydroplaning and reduces visibility.
Step-by-step explanation:
When cars travel on roads, substances such as oil and gasoline can leak and accumulate on the road surface. This build-up generally doesn't pose much of a problem when the road is dry, but the presence of these substances can significantly affect driving conditions when it interacts with rainwater. A light rain can cause the oil and gasoline to rise to the surface, creating a slippery layer that reduces tire traction and thereby, the ability of a driver to control the car. This situation often leads to a higher risk of accidents due to decreased friction between the tires and the road, making it harder to brake and maneuver the vehicle safely.
In contrast, a heavy rain can wash away the oil and gasoline from the road surface, potentially improving traction as compared to conditions during a light rain. However, heavy rain also presents its own challenges such as reduced visibility and potential hydroplaning where the tires lose complete contact with the road surface due to a layer of water. Thus, while heavy rain may initially help to clear away the oil and gasoline, it also requires drivers to exercise caution and adjust their driving to accommodate for the loss of visibility and increased risk of hydroplaning.
Understanding the effect of weather conditions on road surfaces is essential for maintaining safe driving habits. Ensuring proper tire maintenance and selecting appropriate tires, such as those with suitable tread patterns for wet conditions, can help mitigate these risks. Additionally, knowledge of emergency measures, like using gravel ramps in the event of brake failure as seen in Appalachian regions, further enhances driver preparedness for various road scenarios.