STSC Practice Questions (2026) — Free Sample Questions with Answers

Answer: D

Finding 1: A damaged cord must be removed from service, but it is not in use and no one is exposed right now.

Finding 2: A missing tag is a recordkeeping and inspection issue; the extinguisher is still in place.

Finding 3: Material in the walkway is a trip hazard, but its likely severity is lower than a cave-in.

Finding 4: Correct. Workers are in a trench deeper than 5 ft with no protective system: a cave-in can kill in seconds. 29 CFR 1926.652(a)(1) requires protection, so the workers come out immediately.

Correct the finding with people exposed right now to a hazard that can kill or seriously injure them first.

Answer: B

1. Write the formula: N = workers ÷ 40, rounded up.
2. Substitute: N = 95 ÷ 40.
3. Compute: 95 ÷ 40 = 2.375.
4. Round up: 3 toilet seats (with 3 urinals). Check: 2 seats cover only 80 workers, 3 cover 120, which is at least 95.

2: Rounded 2.375 down; a partial facility must be rounded up to a whole one.

3: Correct. 95 ÷ 40 = 2.375, rounded up to 3 toilet seats (and 3 urinals).

4: Added an extra base toilet (1 + 1 per 40); the table gives 1 per 40 with no added base unit.

5: Divided by 20 instead of 40, mixing up the 20-worker threshold with the ratio.

Table D-1: from 20 to 199 workers, 1 toilet seat and 1 urinal per 40 workers, always rounded up.

Answer: C

A concrete chip struck the worker in the left eye: This describes the incident itself, not why it happened.

The worker was not wearing safety glasses at the time: This is the immediate cause; the investigation must still ask why the glasses were off.

Issued glasses fog in humid air and no anti-fog type was stocked: Correct. This is a system-level cause: it explains why the worker removed the glasses and points to a fixable management decision about PPE selection and supply.

The worker was careless and did not think about the eye hazard at all: Blaming carelessness ends the inquiry without finding the condition that led to the behavior.

Keep asking why until you reach a system cause that management can correct; blaming the worker is not a root cause.

Answer: C

Let him wear it if he tightens the head straps a notch past normal: Overtightening does not create a seal through facial hair and makes the mask uncomfortable.

Let him wear it after he passes a positive- and negative-pressure seal check: A user seal check cannot make a tight-fitting facepiece acceptable over facial hair that crosses the sealing surface.

Not assign him a tight-fitting respirator while facial hair crosses the seal: Correct. 29 CFR 1926.103 applies 1910.134(g)(1): tight-fitting facepieces may not be worn by employees with facial hair between the sealing surface and the face; a loose-fitting PAPR hood is an option.

Give him a filtering facepiece (N95) instead of the elastomeric half-mask: An N95 is also a tight-fitting respirator, so the beard defeats its seal just the same.

No facial hair may come between a tight-fitting facepiece and the skin; use a loose-fitting respirator or a clean-shaven seal area.

Answer: B

1. Formula: T = W ÷ (2 × sin θ).
2. Substitute: T = 4,000 lb ÷ (2 × 0.866).
3. Compute: 2 × 0.866 = 1.732; 4,000 ÷ 1.732 = 2,309.5, which rounds to 2,309 lb.
4. Check: each leg carries more than half the load (2,000 lb), as expected for an angled sling, and less than the full 4,000 lb, because 60° is a steep angle.

2,000 lb: Splits the load between the legs but ignores the sling angle, which always raises leg tension.

2,309 lb: Correct. T = 4,000 lb ÷ (2 × 0.866) = 4,000 ÷ 1.732 = 2,309 lb.

4,000 lb: Uses cos 60° (0.500) instead of sin 60°; the angle is measured from the horizontal, so the formula uses sine.

4,619 lb: Divides the whole load by sin 60° without splitting it between the two legs.

Leg tension rises as the sling angle from horizontal decreases; with the angle from horizontal, divide each leg’s share of the load by the sine of the angle.

Answer: D

Normally, if the driver sounds the horn before backing: A horn is not a substitute; the rule requires a working reverse alarm or an observer.

Normally, if the laborers wear high-visibility vests: Vests help visibility but do not meet the rule for a vehicle with an obstructed rear view.

Only after the alarm is repaired at the end of the shift: Repair is needed, but the rule allows backing in the meantime when an observer signals it is safe.

Only when an observer signals that it is safe to back: Correct. 1926.601(b)(4): a vehicle with an obstructed rear view may not reverse unless it has a reverse alarm audible above surrounding noise or is backed only when an observer signals it is safe.

Obstructed rear view: a working reverse alarm audible above the noise, or an observer (spotter) who signals it is safe to back.

Answer: B

1. Rule: horizontal distance from the top support to the foot ≈ working length ÷ 4.
2. Substitute: 20 ft ÷ 4.
3. Compute: 5 ft.
4. Check: the 3 ft of rail above the eave is not part of the working length, so it is not used; 5 ft out for 20 ft along the ladder is the 1:4 ratio.

3.00 ft: Wrong: this confuses the 3-ft extension above the landing with the base distance.

5.00 ft: Correct: 29 CFR 1926.1053(b)(5)(i), the base distance is about one-quarter of the working length: 20 ft ÷ 4 = 5 ft.

5.75 ft: Wrong: this divides the full 23-ft rail length, including the extension above the eave, by 4.

8.00 ft: Wrong: this adds the 3-ft extension to the 5-ft base distance.

Set non-self-supporting ladders with the foot about one-quarter of the working length out from the top support, and extend the rails 3 ft above the landing.

Answer: B

Nothing, because a means of egress is not required until a trench reaches 5 ft in depth: Wrong: 5 ft is the protective-system trigger; egress is required at 4 ft.

Add ladders or ramps so no worker has more than 25 ft of lateral travel to an exit: Correct: 29 CFR 1926.651(c)(2), trenches 4 ft deep or more need a stairway, ladder, ramp or other egress within 25 ft of lateral travel for workers.

Tell the pipe layer to climb out on the pipe bedding stone if needed: Wrong: climbing a spoil or bedding face is not an approved means of egress.

Add one ladder at the west end so each ladder serves a 40-ft section: Wrong: a worker midway could still face about 40 ft of travel, more than the 25-ft limit.

Trench egress starts at 4 ft deep and must be within 25 ft of lateral travel; protective systems start at 5 ft.

Answer: A

Call 911 and start cooling him right away with water and ice: Correct. Confusion and hot skin point to heat stroke, a medical emergency: call EMS and cool the worker immediately (shade, water, ice, fanning) while waiting.

Give him water and let him rest in a truck until he recovers: Wrong: a confused worker may not be able to drink safely, and resting alone delays emergency care.

Have a coworker drive him home to rest for the evening: Wrong: sending him away delays care for a life-threatening condition.

Watch him for 15 minutes to see whether he improves: Wrong: waiting lets core temperature keep rising; heat stroke needs immediate cooling and EMS.

Any change in mental status in the heat means possible heat stroke: call 911 and cool the worker immediately.

Answer: B

1. Formula: Fe = C1/T1 + C2/T2 + …, using the Table D-2 permissible times and counting only levels of 90 dBA or more.
2. 92 dBA: T = 6 h; C/T = 3.0/6 = 0.50.
3. 97 dBA: T = 3 h; C/T = 1.5/3 = 0.50.
4. 100 dBA: T = 2 h; C/T = 0.5/2 = 0.25.
5. 85 dBA: below 90 dBA, not in Table D-2, not counted.
6. Fe = 0.50 + 0.50 + 0.25 = 1.25. Check: Fe > 1, so the shift exceeds the permissible exposure and feasible controls, then hearing protection, are required.

1.00: Wrong: this is total hours ÷ 8 h (8 ÷ 8); it ignores the sound level of each period.

1.25: Correct. 3/6 + 1.5/3 + 0.5/2 = 0.50 + 0.50 + 0.25 = 1.25. The 85-dBA period is below Table D-2 and is not counted. Fe exceeds 1, so the exposure is over the limit.

1.44: Wrong: this counts the 85-dBA period with T = 16 h (3/16 ≈ 0.19); Table D-2 sets no duration below 90 dBA, so that period is not counted.

2.17: Wrong: this recomputes T with a 3-dB exchange rate (about 5.0, 1.6 and 0.8 h) instead of using the Table D-2 values, which use a 5-dB exchange rate.

For mixed noise, add the fractions C/T for each level of 90 dBA or more; a sum above 1 means the permissible exposure is exceeded (1926.52(d)(2)).

Answer: B

Rotate hangers between ceiling and wall work every hour: Wrong: rotation is an administrative control; it spreads the exposure but leaves the overhead lift and hold in place.

Use a mechanical panel lift to raise and hold each board: Correct. The panel lift is an engineering control that removes the overhead lifting and static holding; under the hierarchy of controls, engineering comes before administrative controls and PPE.

Issue padded shoulder supports to each hanger on the crew: Wrong: supports are PPE-type devices with little proven benefit; they do not remove the overhead load.

Hold a group stretching session before each shift starts: Wrong: warm-up stretching does not change the task; the force and awkward posture remain.

For ergonomic hazards, first change the task with equipment (lifts, carts, tool extensions); rotation, stretching and supports are weaker controls.

Answer: C

Hospital and ambulance phone numbers are posted at the truck: Posting numbers is the rule where 911 is not available; here 911 works but cannot locate the caller.

Every worker carries a phone with a charged battery: Working phones are part of the duty, but responders still need to know where the crew is.

The site's latitude and longitude or clear directions are posted: Correct. 29 CFR 1926.50(f)(2) requires employers that use a communication system to reach 911 to post the worksite's latitude and longitude or other clear location information when 911 cannot identify the caller's location automatically.

A landline phone is installed at the right-of-way: A landline with automatic location ID would remove the posting duty, but it is not required and is not practical on a moving rural job.

If 911 cannot locate the caller, post the site's coordinates or other clear location information so responders can find the crew.

Answer: C

Tell crews to evacuate only if a supervisor confirms it: Requiring confirmation delays evacuation and still leaves the alarm ambiguous.

Stop drills until the crane work is finished: Suspending drills removes practice without fixing the confusing signal.

Give the evacuation alarm its own distinct signal: Correct. 29 CFR 1926.35(c)(2) requires a distinctive signal for each purpose when the alarm system is used for more than one. Workers must be able to recognize the evacuation alarm at once.

Sound the horn more times for an evacuation order: More blasts of the same tone are still easy to confuse with the crane warning; a clearly distinct signal is needed.

If an alarm system serves more than one purpose, each purpose must have its own distinct, recognizable signal.

Answer: C

1. Write the formula: N = A ÷ 3,000 ft² per 2A extinguisher, rounded up.
2. Find the area: A = 220 ft × 75 ft = 16,500 ft².
3. Compute: N = 16,500 ÷ 3,000 = 5.5.
4. Round up to a whole extinguisher: 6.
5. Check: 6 × 3,000 = 18,000 ft² ≥ 16,500 ft² (5 would cover only 15,000 ft²); spread the units so travel to the nearest one is 100 ft or less.

3: This divides the 220-ft length by the 100-ft travel distance (2.2 → 3). Travel distance governs placement, not the area-based count.

5: 16,500 ÷ 3,000 = 5.5. Rounding down leaves part of the floor area unprotected; partial results are rounded up.

6: Correct. A = 220 × 75 = 16,500 ft²; N = 16,500 ÷ 3,000 = 5.5, rounded up to 6. Placing the six units evenly also keeps every point within 100 ft of travel.

7: This adds a separate unit for the stairway on top of the area count. The unit beside the stairway can be one of the six.

Divide floor area by 3,000 ft² and round up; then place the units so no one travels more than 100 ft to reach one.

Answer: B

Accept the tickets, since he will still score the bids fairly: Even if his scoring stays fair, the gift creates a conflict of interest and the appearance of compromised judgment.

Decline the tickets and disclose the offer to his employer: Correct. Accepting a gift during the evaluation creates a conflict of interest that could compromise his professional judgment. Standard 6 requires avoiding such conflicts, and telling the employer keeps the process transparent.

Accept the tickets and give them to a crew member instead: Passing the gift on does not remove the obligation that accepting it creates toward the supplier.

Accept the tickets but score that supplier lower to stay neutral: Adjusting scores to offset the gift is still biased judgment and is unfair to the supplier.

Standard 6: avoid conflicts of interest that compromise professional judgment. Decline the gift and disclose the offer.

Answer: B

Allow the task if the two workers agree to stay low and move slowly: Consent and care do not control a fall exposure 18 ft above grade. Fall protection is still required.

Keep them back until fall protection is in place and explain the risk: Correct. The Code says to hold the safety of people paramount and to advise employers of danger (Standard 1). The 6-ft trigger in 1926.501(b) applies however short the task is, so the foreman explains the danger to the superintendent.

Allow the task and write up the superintendent's request in the daily log: Documenting the request after the fact does not protect the workers while they are exposed.

Set the materials at the edge himself so no crew member is exposed: The foreman is still a person exposed to an 18-ft fall. Holding safety paramount includes his own safety.

Leadership means stopping unsafe work and advising the employer of the danger. Fall protection is required at 6 ft regardless of how long the task takes.