CPC CPC Construction Equipment & Temporary Structures 2 — Questions and Answers
Question 1: What does the term 'factor of safety against overturning' mean for a temporary retaining structure?
- The ratio of resisting moments to overturning moments (Correct answer)
- The ratio of active to passive earth pressure
- The maximum soil bearing pressure allowed
- The safety factor applied to steel yield strength
Correct answer: The ratio of resisting moments to overturning moments
The factor of safety against overturning is the ratio of stabilizing (resisting) moments to destabilizing (overturning) moments about the toe of the structure.
Question 2: In earthmoving operations, what does the 'swell factor' account for?
- The increase in soil volume when excavated from bank state to loose state (Correct answer)
- The shrinkage of fill after compaction
- The moisture gain during rainy periods
- The difference between summer and winter soil density
Correct answer: The increase in soil volume when excavated from bank state to loose state
Swell factor accounts for the volume increase (typically 20–40%) that occurs when in-situ (bank) soil is excavated and becomes loose material.
Question 3: What is the primary hazard of using a rough-terrain forklift on a sloped surface?
- Overheating the engine
- Lateral tipover due to a shifted center of gravity on the slope (Correct answer)
- Tire wear exceeding limits
- Hydraulic pressure loss
Correct answer: Lateral tipover due to a shifted center of gravity on the slope
Rough-terrain forklifts are vulnerable to lateral tipover on slopes because the elevated load shifts the combined center of gravity outside the stability triangle.
Question 4: Which OSHA standard governs the use of personnel hoists (elevators) on construction sites?
- 29 CFR 1926 Subpart Q
- 29 CFR 1926 Subpart R
- 29 CFR 1926 Subpart CC
- 29 CFR 1926 Subpart N (Correct answer)
Correct answer: 29 CFR 1926 Subpart N
OSHA 29 CFR 1926 Subpart N covers the use of material hoists, personnel hoists, and elevators on construction sites.
Question 5: What is the minimum horizontal distance from the edge of an excavation that heavy equipment must be positioned to prevent surcharge loads from causing cave-ins?
- 2 feet
- At a distance equal to or greater than the depth of the excavation, or per geotechnical analysis (Correct answer)
- 6 feet
- 10 feet always
Correct answer: At a distance equal to or greater than the depth of the excavation, or per geotechnical analysis
OSHA requires that equipment and spoil be stored away from excavation edges at a distance that prevents surcharge from exceeding the soil's bearing capacity, with the minimum typically equaling excavation depth.
Question 6: A 'load moment indicator' (LMI) on a mobile crane is designed to:
- Measure the weight of outrigger pads
- Warn the operator when the load approaches or exceeds the crane's rated capacity (Correct answer)
- Calculate fuel consumption per lift
- Automatically level the crane on uneven ground
Correct answer: Warn the operator when the load approaches or exceeds the crane's rated capacity
An LMI (also called a rated capacity indicator) monitors load and radius in real time and alerts the operator before the crane reaches its tipping or structural load limit.
CPC CPC Construction Equipment & Temporary Structures 2
What does the term 'factor of safety against overturning' mean for a temporary retaining structure?