What factor contributes to a bus becoming unstable on a banked curve?

The speed of the vehicle significantly contributes to a bus becoming unstable on a banked curve. When a bus approaches or navigates through a banked curve at high speeds, the centrifugal force acting on the bus increases. This force pushes the vehicle outward and can lead to a loss of traction or control, particularly if the speed exceeds the recommended limits for that specific curve.

In essence, if the speed is too high, it can compromise the effectiveness of the bank, which is designed to help counteract this outward force. The combination of excessive speed and the angle of the bank creates conditions that can lead the bus to tip or skid, particularly if combined with other factors such as sharp turns or an uneven load. Understanding the dynamics of speed on banked curves is crucial for safe bus operation, which is especially important given the size and weight of the vehicle. Therefore, slowing down and maintaining a speed appropriate for the curve is essential for ensuring stability and safety while navigating these kinds of road features.