Which of the following is NOT a special condition for downshifting?

When considering the conditions for downshifting, it's important to recognize scenarios where changing gears can aid in controlling the vehicle effectively. Downshifting generally helps in situations that require increased control, such as reducing speed or maintaining stability.

Before entering a curve, for example, downshifting allows for better traction and control as the vehicle navigates the turn. Similarly, before starting down a hill, downshifting helps manage the vehicle's speed by using engine braking, which reduces reliance on the brakes and prevents overheating. Additionally, slowing down for traffic is another situation where downshifting is beneficial as it allows the driver to reduce speed smoothly, preparing for potential stops.

Crossing railroad tracks, however, does not typically require downshifting. While attention should be given to the approach and crossing itself, this scenario does not present the same challenges or need for speed control that the other options do. Therefore, it is not considered a special condition for downshifting, making it the correct answer in this context.