What must be provided along haulage roads to ensure the safety of those passing moving cars?

The correct answer emphasizes the importance of both providing sufficient clearance and the implementation of shelter holes along haulage roads for safety. A clearance of at least 24 inches is crucial because it allows individuals to have adequate space to pass without the risk of being struck by moving vehicles. This distance is significant enough to account for variations in individual sizes and to provide a buffer in case of unexpected movements or slips.

Additionally, shelter holes are vital in providing a safe refuge for workers or pedestrians when a vehicle approaches. These should be strategically placed along the roads to allow passing individuals the chance to step aside without risking injury. This combined approach addresses both the need for physical space between pedestrians and vehicles and offers a contingency plan with the shelter holes for heightened safety.

While other options may contribute to safety, such as signaling drivers or ensuring proper lighting, they do not address the physical requirements of space and the provisions needed for emergencies as effectively as sufficient clearance and shelter holes do.