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58 Cards in this Set
- Front
- Back
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What are the Basic Factors in Estimating Production?
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Loads (Payloads) -> Units/Round Trip (cycle)
Cycle Times -> Cycles/Time period or round trips/time period |
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Basic Relationship for Production
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Production = units/cycle x cycles/time period
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Basic Relationship for yd3/hr
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yd3/hr = yd3/cycle x cycles/hr
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Material Carried is determined by
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Volume Capacity and Weight Capacity
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Number of Cycles per hour is determined by
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Cycle time, efficiency and production hour
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What happens to the volume of material as it is excavated, hauled and compacted?
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Material will expand when excavated and contract when compacted. You will more than likely compact more than in its original location/
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What are the steps as material moves from in the ground to out to back in?
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Bank, Loose, Compacted
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How can you convert between bank, loose and compacted volumes?
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Using unit weights, factors and percents
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What does the load factor convert?
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Converts LCY to BCY
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What does the Shrinkage factor convert?
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From BCY to CCY
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What does Swell represent?
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The percent increase in volume from Bank to Loose.
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What does Shrinkage represent?
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The percent decrease in volume from Bank to Compacted
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What is a typical cycle for hauling earth?
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Load, haul, dump, return
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What factors determine the time for the various cycle time components?
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Size of material, size of loading equipment, size of hauler, haul distance and speed of travel
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What is cycle time?
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The time it takes a machine to complete a circuit of operations
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What is the speed of a hauling unit governed by?
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Power required (grade and surface)
Power available (Engine output) Power usable (traction and altitude) |
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How is the Power Required determined?
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Rolling resistance (RR) (Surface conditions)
Grade resistance (GR) (Slope) |
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Rolling Resistance general rule of thumb equation
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40 lb/ton + 30 lb/ton for every inch of penetration
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Equation for Grade Resistance
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Grade Resistance = Percent grade x 20lb/ton x weight on the wheels
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Equation for power required
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Rolling resistance + Grade resistance
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What determines the power available?
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Engine size and gear
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What is power available measured in?
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Drawbar pull (tracked vehicles)
Rimpull (wheeled vehicles) |
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What is the equation for Total Resistance (TR)?
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Grade + Rolling Resistance (RR)/20
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What is the equation for rimpull?
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Weight of vehicle x Total Resistance (TR)
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What are travel time curves?
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Graphs that take acceleration and deceleration in to consideration
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Equation for Usable pounds pull
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coefficient of traction x weight on drivers
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What is usable power determined by?
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Road surface traction characteristics and altitude
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What is the rule of thumb for altitude on usable power?
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Deceases pounds pull 3% for each 1000 ft above 3000 ft
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What is a Balanced Fleet?
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No waiting time for any system component
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What is a balance point?
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The number of haulers that can exactly accommodate the production of the loader. Where there is no waiting for the haulers or loader
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What factors help determine the number of hauling units to use?
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What is the goal
Maximize production Minimize cost/unit |
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What are the two purposes of cost estimates?
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To establish the approximate cost of the project
To establish a budget against which to control costs during project execution |
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What are the types of estimates for Building construction projects?
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Conceptual
Preliminary Engineer's Bid |
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What are the types of estimates for Industrial construction projects?
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Magnitude
Conceptual Preliminary Definitive Engineer's Bid |
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Examples of parametric estimating?
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$/SF for a house or $/CF for a warehouse
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What are the two ways to estimate construction costs?
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Consider the combined total labor and all materials
Estimate costs by discrete work packages or cost centers |
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Estimates involving combining total labor and materials
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Easier to estimate
Almost impossible to use as a project control tool |
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Estimates using cost centers
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more time consuming to estimate
Allows use as a project control tool |
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Steps in the detailed estimating process
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Break project into cost centers
Preform a quantity takeoff Price the quantities determined in the quantity takeoff |
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Sources for cost information in finding the price of quantities determined in the quantity takeoff
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Historical data
Vender quotes Supplier catalog |
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Steps in determining unit prices to use
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Determine crew composition and equipment
Estimate ideal production Estimate an efficiency factor Calculate the effective unit price |
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Methods of detailed cost determination
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Unit pricing
Resource enumeration |
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Advantage of unit pricing
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simplicity
units/($/unit) = $ |
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Disadvantage of unit pricing
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may not be historically accurate data for project
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How to use resource enumeration for detailed cost determination.
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Sum costs of all required resources
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When to use resource enumeration?
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If unit prices are not available
If unit prices do not apply due to the uniqueness of the project |
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What are fringe benefits?
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vacation, health and welfare, pension
usually expressed as a hourly cost added to base wage rate |
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FICA
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Federal Insurance Contributions Act
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What does FICA include?
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Social security and medicare
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What does EMR stand for
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Experience modification ratio
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Equation for effective grade
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Effective Grade = grade + Rolling Resistance Factor/20
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Would a contractor rather have an EMR less than or greater than 1.0
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Less than because we will pay less
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What determines the maximum power usable in 1st gear?
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The traction limit
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What determines the maximum speed for a job using a tractor
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The power required
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How do you find the gross weight of a tractor?
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Divide the max power by the coefficient of traction for the road
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What is the equation for traction limit?
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traction limit = coefficient of traction x gross weight of vehicle
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Is it possible to have a negative shrinkage factor?
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No
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What is the equation for workers compenstion premium?
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workers comp premium = hours per week x wages per hour x (workers comp rate/100)
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