What action should a driver take upon seeing the sign indicating a 15% downgrade?

When a driver encounters a sign indicating a 15% downgrade, it is essential to prepare to slow down and shift gears. This type of sign warns of a steep decline ahead, which can significantly affect the vehicle's speed and control.

As vehicles go downhill, gravity increases their speed, making it more challenging to maintain control. By preparing to slow down, the driver can better manage their speed as they descend, reducing the risk of losing control or experiencing brake failure from overheating. Shifting to a lower gear allows the engine to help slow the vehicle down, utilizing engine braking rather than relying solely on the brakes. This combination is crucial for safely navigating a steep downhill grade, ensuring that the driver maintains control and avoids potential accidents.

In contrast, increasing speed, staying in the lane without caution, or continuing at the current speed completely disregard the hazards presented by the downgrade, potentially leading to dangerous situations. Prioritizing a controlled descent is essential for safety in such conditions.