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20 multiple-choice questions and 7 flashcards on Focus Four — Struck-By, about 7% of the OSHA 30 bank. Every one carries a written rationale.
Focus Four — Struck-By is one of 10 chapters in CoStudy's OSHA 30 (Construction) bank, and it holds 20 of the bank's 300 multiple-choice questions — roughly 7% of the total. That proportion is not arbitrary: chapters follow the certifying body's published exam outline, and the number of questions in each is set by that domain's published weight, so the share of your practice time this chapter takes matches the share of the real exam it accounts for.
Studying by chapter is worth doing once you have a diagnostic score. A single overall percentage tells you whether you are close; it does not tell you which domain is dragging. Working a weak chapter in isolation, and re-testing it in isolation, is the fastest way to move a score that has stalled — and it is why the mock exams in CoStudy report by domain rather than as one number.
5 questions drawn from this chapter, with the full rationale shown — the controlling principle behind the right answer, and why each wrong option tempts and fails.
Who may enter a limited access zone at a masonry wall under construction?
Answer: D — Only workers actively engaged in building the wall
D) Correct — the zone is restricted to those building the wall, which keeps others out of the collapse footprint. A) PPE does not authorize entry into a collapse zone. B) Employer identity does not create an entry right. C) Escorting does not reduce the collapse hazard.
Workers exposed to vehicular traffic must wear high-visibility apparel that meets:
Answer: D — ANSI/ISEA 107 Class II or III
Class II for moderate traffic, Class III for high-speed/low-light. Class I is for off-road only.
A spotter is guiding a backing loader. Which practice is MOST important for the spotter?
Answer: C — Keeping visual contact with the operator and out of the path
C) Correct — if the operator cannot see the spotter, the spotter must be assumed to be at risk, and the spotter must never be in the path. A) Standing in the path is exactly how spotters are killed. B) Phone use divides attention for both parties. D) Dark clothing reduces conspicuity; high-visibility apparel is the requirement.
When a crane is operating, the swing radius of the rotating superstructure must be:
Answer: D — Barricaded to prevent worker entry
Physical barricade is required.
A hard hat is required in which of the following situations?
Answer: D — Where falling objects or overhead electrical hazards exist
D) Correct — head protection is required where falling or flying objects or overhead electrical contact could cause head injury. A) Crane operation is one trigger among many. B) Confuses a fall protection trigger height with head protection. C) Insurance terms do not define the requirement.
4 cards from the 7 in this chapter.
What is the primary control for struck-by hazards from materials stored on an elevated surface?
Toeboards, screens, or guardrail systems to keep materials from falling, plus debris nets or catch platforms and barricades in the area below where objects could land.
Under what condition must a masonry wall over 8 feet high be braced, and what area must be restricted?
Until permanent supporting elements are in place, it must be adequately braced. A limited access zone equal to the wall height plus 4 feet must be established on the unscaffolded side and entered only by workers building the wall.
Name three common struck-by hazards involving powered equipment and their controls.
Flying particles from grinding or nailing — eye and face protection and tool guards • Swinging loads from cranes — taglines and keeping out from under loads • Moving haul trucks — traffic control plans, seat belts, and spotters.
What class of high-visibility apparel is required for workers exposed to traffic in a highway work zone?
ANSI/ISEA 107 Class 2 minimum for roadway work above about 25 mph or complex backgrounds; Class 3 for high-speed highways, night work, and flagger operations with reduced sight distance.
These are a sample. The full Focus Four — Struck-By chapter runs 27 items with per-chapter progress tracking, on the web and in the iOS app.