Excavator Operation and Efficiency Quiz
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Questions and Answers

Assuming 8-hr workdays, the number of days required to complete the excavation job with a 2.8 yd³ bucket capacity is most nearly:

  • 10 (correct)
  • 13
  • 9
  • 11

The number of trucks needed to balance the production of an excavator with a bucket capacity of 3.0 yd³ is most nearly:

  • 5
  • 4 (correct)
  • 2
  • 3

The complete cost ($) of the change order for the revised SOW for the warehouse building is most nearly:

  • 7,800 (correct)
  • 9,800
  • 3,300
  • 4,200

The total material cost ($) for lining a canal with concrete is most nearly:

<p>85,000 (A)</p> Signup and view all the answers

The number of dump trucks needed to haul excavated material from a site is most nearly:

<p>4 (C)</p> Signup and view all the answers

The project duration (weeks) for the summarized project activities is most nearly:

<p>41 (B)</p> Signup and view all the answers

What is the swell percentage of the material to be excavated?

<p>20%</p> Signup and view all the answers

What is the in situ unit weight of the excavated material?

<p>120 lb/ft³</p> Signup and view all the answers

What is the stated truck capacity for transporting the excavated material?

<p>15 yd³</p> Signup and view all the answers

Flashcards

Excavator cycle time

The total time an excavator takes to complete one cycle of excavation, travel, and dumping.

Material swell

The increase in volume of material during excavation.

Truck cycle time

The total time a truck takes to complete a trip, including transfer, travel, and dumping.

Critical path

The longest path through a project network of activities.

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Project duration

The total time required to complete the entire project

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Project schedule

A planned sequence of activities to complete the project

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Construction Costs

Total costs related to materials and labour needed for projects.

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Swell Factor

Percentage increase in volume of excavated material after removal from ground.

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Excavation Efficiency

Ratio of actual excavation production to maximum possible production.

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Labor Productivity

Measure of the output per unit of labor input in a given period.

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Study Notes

Excavator Operation Cycle

  • Bucket Capacity: 2.8 yd³ (or 3.0 yd³)
  • Phases (Example): Excavation, travel (two-way), dumping/transfer
  • Excavation Time: 45 seconds
  • Travel Time (Two-way): 4 minutes
  • Transfer/Dumping Time: 30 seconds (or 45 seconds)
  • Overall Efficiency: 85% (or 90%)
  • Material to be Excavated: 50,000 ft³ (or 2,600 yd³ loose)
  • Material Properties (Example): Swell = 20%, In situ unit weight = 120 lb/ft³, Water content = 30%
  • Workday: 8 hours

Number of Days Required

  • Calculation: Determined by the excavator's cycle time and efficiency, and the total material volume to be excavated.
  • Example Answers: A. 9, B. 10, C. 11, D. 13 (depending on the details)

Truck Capacity and Operational Data

  • Truck Capacity: 15 yd³
  • Truck Cycle Time: 90 minutes
  • Other Data: Overall efficiency factor, excavator output, excavated material, etc.

Warehouse Building Design Change

  • Revised Design: Replacing one layer of sheetrock with two layers of fire-code GWB and insulation.
  • Dimensions: 180 ft × 200 ft, 12 ft floor-to-ceiling height, 8 openings (6ft wide x 10ft high)
  • Labor: Carpenter foreman ($50.00), Carpenter ($40.00), Laborer ($25.00)
  • Work Crew: 4 carpenters, 2 laborers, 1 foreman
  • Work Crew Productivity: GWB installation 960 ft²/L.H., Insulation 1,920 ft²/L.H.

Material Costs

  • GWB Costs: 4 ft x 10 ft x 1½ in. GWB ($0.285/ft²), 4 ft x 10 ft x 5/8 in. GWB ($0.255/ft²)
  • Insulation Costs: $0.45/ft²
  • Waste Factor: 10%
  • Contractor Overhead/Profit: 10% and 5%, respectively
  • Total Cost: Approximately $3,300,4,200,9,800,7,800 (depending on calculations)

Additional Factors

  • Dump Truck Productivity: 0.80 for equipment idle time and 0.70 for operator efficiency are factors that need to be considered.
  • Number of Trucks Needed: Calculated from excavator output, truck capacity, travel time and job location.
  • Project Duration (weeks): 32, 36, 41, or 44
  • Total Material Cost: ~ $75,000, $85,000, $95,000 or $105,000
  • Concrete Costs: $98/yd³, 8 in. Nominal thickness, 8 yd³/hour pour rate, 300 ft²/gal coverage
  • Canal LIning Materials: Includes concrete, pour rate, surfacing compound.

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Description

Test your knowledge on the operation cycle of excavators, including phases like excavation, travel, and dumping. This quiz covers calculations related to bucket capacity, material excavation requirements, and truck cycle times. Perfect for engineering students and professionals in construction.

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