Which of the following is NOT a main type of scaffold?

The correct answer is service scaffolds because they are not classified as a main type of scaffold in the context of OSHA standards. Scaffolds are primarily categorized into supported scaffolds and suspended scaffolds, which are specifically designed for providing platforms for workers to perform their tasks at elevated heights.

Supported scaffolds are erected using rigid support structures that can either be made from wood or metal. They are fixed in place and provide a stable platform for workers. Suspended scaffolds, on the other hand, are platforms that hang from an overhead structure and can be raised or lowered to reach various heights.

Aerial lifts are specialized equipment that allow workers to lift to elevated positions but they do not fall under the traditional scaffold categories defined by OSHA. They are classified separately as lifting equipment.

Thus, service scaffolds, while they may refer to temporary structures used for specific tasks, do not meet the standard definitions and classifications laid out by OSHA for scaffolding types.