OSHA construction excavations practice questions
20 free practice questions from 29 CFR 1926 Subpart P. Each answer is explained and linked to the rule it comes from.
OSHA Excavations
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Scope and definitions
1. Forms are built inside a wide excavation. When does Subpart P say the excavation is also considered a trench?
- A. When the forms are taller than 5 feet
- B. When the forms reduce the dimension from the forms to the side of the excavation to 15 feet or less, measured at the bottom
- C. Only when the excavation is deeper than 20 feet
- D. Never; only the original width decides it
Show answer
Answer: B. When the forms reduce the dimension from the forms to the side of the excavation to 15 feet or less, measured at the bottom
"If forms or other structures are installed or constructed in an excavation so as to reduce the dimension measured from the forms or structure to the side of the excavation to 15 feet (4.6 m) or less (measured at the bottom of the excavation), the excavation is also considered to be a trench."
2. Apart from approving manufactured protective systems or tabulated data for interstate commerce, in which state must a "registered professional engineer" under Subpart P be registered?
- A. The state where the employer has its head office
- B. The state where the engineer lives
- C. Any state at all
- D. The state where the work is to be performed
Show answer
Answer: D. The state where the work is to be performed
A registered professional engineer "means a person who is registered as a professional engineer in the state where the work is to be performed." Registration in any state counts only for those interstate design approvals.
Access and egress
3. A structural ramp is used in place of steps for employees to get into an excavation. What does Subpart P require on the ramp's top surface?
- A. Cleats or other surface treatments to prevent slipping
- B. A coat of high-visibility paint only
- C. Nothing beyond the ramp's structural design
- D. A rubber mat at the top end only
Show answer
Answer: A. Cleats or other surface treatments to prevent slipping
"Structural ramps used in lieu of steps shall be provided with cleats or other surface treatments on the top surface to prevent slipping."
Source: eCFR: 29 CFR 1926.651, Specific excavation requirements (as of Nov 3, 2026)
4. A ramp into an excavation is built from two or more structural members. What does Subpart P require of those members?
- A. They must be painted a high-visibility color
- B. They must be spaced at least 1 inch apart
- C. They must be connected together to prevent displacement
- D. They must be laid loose so they can be moved quickly
Show answer
Answer: C. They must be connected together to prevent displacement
"Ramps and runways constructed of two or more structural members shall have the structural members connected together to prevent displacement."
Source: eCFR: 29 CFR 1926.651, Specific excavation requirements (as of Nov 3, 2026)
Surface encumbrances and underground installations
5. The utility owners cannot establish the exact location of an underground line near a planned trench. Under what condition may the employer proceed with the excavation?
- A. Only if the excavation will be less than 4 feet deep
- B. Only after OSHA approves the dig
- C. With caution, using detection equipment or other acceptable means to locate the installations
- D. Never; work must stop until the utility marks the line
Show answer
Answer: C. With caution, using detection equipment or other acceptable means to locate the installations
When utilities cannot respond in time "or cannot establish the exact location of these installations, the employer may proceed, provided the employer does so with caution, and provided detection equipment or other acceptable means to locate utility installations are used."
Source: eCFR: 29 CFR 1926.651, Specific excavation requirements (as of Nov 3, 2026)
Water, adjacent structures and falling material
6. When may an excavation undermine a sidewalk or pavement?
- A. Only when a support system or another method of protection protects employees from the possible collapse of such structures
- B. Whenever no vehicles are parked on it
- C. Whenever the excavation is less than 4 feet deep
- D. Whenever the work will be finished the same day
Show answer
Answer: A. Only when a support system or another method of protection protects employees from the possible collapse of such structures
"Sidewalks, pavements, and appurtenant structure shall not be undermined unless a support system or another method of protection is provided to protect employees from the possible collapse of such structures."
Source: eCFR: 29 CFR 1926.651, Specific excavation requirements (as of Nov 3, 2026)
7. When water removal equipment is used to control water in an excavation, who must monitor the equipment and operations?
- A. The utility company
- B. A competent person
- C. A registered professional engineer
- D. The local fire department
Show answer
Answer: B. A competent person
"The water removal equipment and operations shall be monitored by a competent person to ensure proper operation."
Source: eCFR: 29 CFR 1926.651, Specific excavation requirements (as of Nov 3, 2026)
Hazardous atmospheres
8. Ventilation is being used to bring atmospheric contaminants in an excavation down to acceptable levels. How often must the atmosphere be tested?
- A. Once, at the start of the job
- B. Once a week
- C. Only when someone notices an odor
- D. As often as necessary to ensure that the atmosphere remains safe
Show answer
Answer: D. As often as necessary to ensure that the atmosphere remains safe
"When controls are used that are intended to reduce the level of atmospheric contaminants to acceptable levels, testing shall be conducted as often as necessary to ensure that the atmosphere remains safe."
Source: eCFR: 29 CFR 1926.651, Specific excavation requirements (as of Nov 3, 2026)
9. Hazardous atmospheric conditions may reasonably be expected to develop in an excavation. Which of these is listed as emergency rescue equipment that must be readily available?
- A. A portable fire extinguisher only
- B. Breathing apparatus, a safety harness and line, or a basket stretcher
- C. A first aid kit only
- D. A two-way radio only
Show answer
Answer: B. Breathing apparatus, a safety harness and line, or a basket stretcher
"Emergency rescue equipment, such as breathing apparatus, a safety harness and line, or a basket stretcher, shall be readily available where hazardous atmospheric conditions exist or may reasonably be expected to develop during work in an excavation."
Source: eCFR: 29 CFR 1926.651, Specific excavation requirements (as of Nov 3, 2026)
10. Subpart P requires the atmosphere to be tested before employees enter excavations greater than 4 feet deep where a hazardous atmosphere could reasonably be expected to exist. Which setting does it give as an example of such a place?
- A. Excavations in landfill areas
- B. Excavations in stable rock
- C. Excavations dug only with hand tools
- D. Excavations less than 100 feet long
Show answer
Answer: A. Excavations in landfill areas
Testing applies where a hazardous atmosphere "exists or could reasonably be expected to exist, such as in excavations in landfill areas or excavations in areas where hazardous substances are stored nearby."
Source: eCFR: 29 CFR 1926.651, Specific excavation requirements (as of Nov 3, 2026)
11. An employee entering a bell-bottom pier hole wears a harness with a lifeline. What does Subpart P require of that lifeline?
- A. It may double as the line used to handle materials
- B. It needs attending only while the employee enters and exits
- C. It must be separate from any material-handling line and individually attended at all times
- D. It is needed only when the hole is deeper than 20 feet
Show answer
Answer: C. It must be separate from any material-handling line and individually attended at all times
"The lifeline shall be separate from any line used to handle materials, and shall be individually attended at all times while the employee wearing the lifeline is in the excavation."
Source: eCFR: 29 CFR 1926.651, Specific excavation requirements (as of Nov 3, 2026)
Inspections by a competent person
12. Subpart P requires daily inspections of excavations by a competent person. In what circumstance does it say those inspections are required?
- A. Only for excavations deeper than 20 feet
- B. Only when OSHA requests one
- C. Only for excavations open longer than a week
- D. Only when employee exposure can be reasonably anticipated
Show answer
Answer: D. Only when employee exposure can be reasonably anticipated
"These inspections are only required when employee exposure can be reasonably anticipated."
Source: eCFR: 29 CFR 1926.651, Specific excavation requirements (as of Nov 3, 2026)
13. When the competent person finds evidence of a situation that could result in a possible cave-in, what does Subpart P require?
- A. Employees keep working while the competent person watches the face
- B. The employer files a report with OSHA within 24 hours
- C. The employer posts a warning sign at the edge
- D. Exposed employees are removed from the hazardous area until the necessary precautions have been taken
Show answer
Answer: D. Exposed employees are removed from the hazardous area until the necessary precautions have been taken
In that case "exposed employees shall be removed from the hazardous area until the necessary precautions have been taken to ensure their safety."
Source: eCFR: 29 CFR 1926.651, Specific excavation requirements (as of Nov 3, 2026)
Protective systems
14. In a trench, material may be excavated up to 2 feet below the bottom of the members of a support system only if what is true?
- A. The trench is less than 10 feet deep
- B. The system is designed to resist the forces calculated for the full depth of the trench, and there are no indications of a possible loss of soil from behind or below the bottom of the support system
- C. A competent person is present at the trench
- D. The soil has been classified as Type C
Show answer
Answer: B. The system is designed to resist the forces calculated for the full depth of the trench, and there are no indications of a possible loss of soil from behind or below the bottom of the support system
This is permitted "only if the system is designed to resist the forces calculated for the full depth of the trench, and there are no indications while the trench is open of a possible loss of soil from behind or below the bottom of the support system."
Source: eCFR: 29 CFR 1926.652, Requirements for protective systems (as of Nov 3, 2026)
15. When may employees work on the face of a sloped or benched excavation at a level above other employees?
- A. Whenever the upper employees work slowly
- B. Whenever they are within 25 feet of a ladder
- C. Only when the employees at the lower levels are adequately protected from falling, rolling, or sliding material or equipment
- D. Whenever the benches are less than 4 feet high
Show answer
Answer: C. Only when the employees at the lower levels are adequately protected from falling, rolling, or sliding material or equipment
"Employees shall not be permitted to work on the faces of sloped or benched excavations at levels above other employees except when employees at the lower levels are adequately protected from the hazard of falling, rolling, or sliding material or equipment."
Source: eCFR: 29 CFR 1926.652, Requirements for protective systems (as of Nov 3, 2026)
16. Who must approve a sloping or benching system that does not use Option (1), (2) or (3)?
- A. A registered professional engineer
- B. The equipment operator
- C. The utility company
- D. The property owner
Show answer
Answer: A. A registered professional engineer
Such systems "shall be approved by a registered professional engineer."
Source: eCFR: 29 CFR 1926.652, Requirements for protective systems (as of Nov 3, 2026)
17. Where must the removal of a support system begin?
- A. At the top of the excavation
- B. At the bottom of the excavation
- C. At the end nearest the spoil pile
- D. At the middle of the trench
Show answer
Answer: B. At the bottom of the excavation
"Removal shall begin at, and progress from, the bottom of the excavation."
Source: eCFR: 29 CFR 1926.652, Requirements for protective systems (as of Nov 3, 2026)
18. Employees are not allowed inside a shield while the shield is being what?
- A. Installed, removed, or moved vertically
- B. Inspected by the competent person
- C. Used in Type A soil
- D. Used in a trench less than 8 feet deep
Show answer
Answer: A. Installed, removed, or moved vertically
"Employees shall not be allowed in shields when shields are being installed, removed, or moved vertically."
Source: eCFR: 29 CFR 1926.652, Requirements for protective systems (as of Nov 3, 2026)
Soil classification and sloping (Appendices A and B)
19. After a soil deposit has been classified, the conditions affecting its classification change. What does Appendix A require?
- A. The original classification stays for the life of the job
- B. The deposit is re-tested once a year
- C. A registered professional engineer must redesign every protective system on site
- D. A competent person evaluates the changes, and the deposit is reclassified as necessary
Show answer
Answer: D. A competent person evaluates the changes, and the deposit is reclassified as necessary
"If, after classifying a deposit, the properties, factors, or conditions affecting its classification change in any way, the changes shall be evaluated by a competent person. The deposit shall be reclassified as necessary to reflect the changed circumstances."
Source: eCFR: 29 CFR Part 1926, Subpart P, Appendix A (as of Nov 3, 2026)
20. During sloping work, small pebbles and clumps keep suddenly separating from the excavation face and trickling down. How does Appendix B treat this?
- A. As normal settling that needs no action
- B. As proof that the soil is Type A
- C. As ravelling, a sign of distress, so the actual slope must be less steep than the maximum allowable slope
- D. As a sign of dry soil, which allows a steeper slope
Show answer
Answer: C. As ravelling, a sign of distress, so the actual slope must be less steep than the maximum allowable slope
"Distress means that the soil is in a condition where a cave-in is imminent or is likely to occur," and it includes ravelling. "The actual slope shall be less steep than the maximum allowable slope, when there are signs of distress."
Source: eCFR: 29 CFR Part 1926, Subpart P, Appendix B (as of Nov 3, 2026)