Under what circumstance may you pass on a shoulder?

Passing on a shoulder is allowed when a vehicle is turning left and the shoulder is paved. This situation presents a specific context where it is both safe and legal to maneuver around the left-turning vehicle. The presence of a paved shoulder indicates that it is a designed space for such maneuvers, facilitating a smoother and safer flow of traffic.

In contrast, passing on an unpaved shoulder may not provide the same safety and control as a paved surface. Additionally, overtaking a cyclist requires caution due to the vulnerability of cyclists on the road, and specific rules and distances must be followed that often prevent shoulder passing. Lastly, heavy traffic does not justify passing on the shoulder; such actions could create hazardous situations and lead to violations of traffic laws. Thus, the specific scenario of a left-turning vehicle creates a legitimate opportunity to use the shoulder safely.