Final answer:
OSHA standards prohibit excavation without an appropriately designed support system to prevent cave-ins and protect workers, and thus excavation without any support system is not permitted.
Step-by-step explanation:
The question regarding OSHA standards relates to safety measures required during excavation work, specifically under sidewalks and pavement. OSHA's safety requirements mandate that employers must ensure a safe work environment for their workers and need to implement safety methods that are feasible. For excavation work, this includes having an appropriately designed support system to prevent cave-ins and to safeguard the workers operating in or around the excavation site. Therefore, the correct answer is OSHA standards prohibit excavation without an appropriately designed support system.
OSHA regulations are in place to protect workers from serious hazards, especially in construction and excavation contexts. When working under sidewalks and pavement, employers are required to use protective systems like shoring, sloping, benching, or other equivalent systems to ensure the trenches are safe for workers. Simply put, OSHA standards expressly prohibit excavation without any support system, given the serious risk of collapses and subsequent injuries that could occur.