Which factors determine a safe speed down a steep grade?

The factors that determine a safe speed down a steep grade primarily include the length of the grade and the weather conditions. The length of the grade affects how long a driver has to manage their speed and braking, especially on longer descents where brakes may overheat if used continuously. Weather conditions such as rain, snow, or ice can also significantly impact traction, making it crucial to adjust speed accordingly to maintain control of the vehicle.

Considering these elements ensures that the driver can maintain safety while descending. It’s essential to recognize that a steep, long grade combined with adverse weather requires different speed management compared to a short, dry incline. Other factors, like grade steepness and vehicle weight, also play roles, but they don't encompass the full context as well as length and weather do.