When should you not start to pass another vehicle?

Passing another vehicle within one-third of a hill or curve is dangerous because visibility is significantly reduced in these situations. When you are approaching a hill or curve, you may not be able to see oncoming traffic, making it unsafe to attempt a pass. This can lead to serious collisions since you may not be aware of vehicles approaching from the opposite direction.

In contrast, starting to pass another vehicle at a traffic signal or a stop sign is also ill-advised, but in those cases, the context may involve stopping or waiting for the signal, which is not the same as the immediate risks associated with poor visibility on hills or curves. Driving below the speed limit does not inherently relate to safety regarding passing; instead, it is important to assess conditions and signals to determine if passing is appropriate.