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2.4. Unit Cost of Production in Earthmoving Operation
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Today, we will discuss the cycle time of a bulldozer. Cycle time includes push time, backtrack time, and maneuver time. Can anyone tell me what push time is?
Isn't that the time it takes to move the earth forward?
Exactly! Push time is influenced by the haul distance. What about backtrack time?
That's when the bulldozer returns to the original position, right?
Correct! Backtrack time is generally shorter than push time because the blade is empty. Now, let's discuss maneuver time.
Is that the time it takes to change gears or adjust speed?
Great! It varies depending on whether the bulldozer has automatic or manual gear changes. Remember, we categorize push and backtrack time as variable time and maneuver time as fixed time.
To summarize, cycle time is made up of three components: push time, backtrack time, and maneuver time, with varying influences depending on distance and machine type.
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Now let's discuss how we estimate bulldozer productivity. What do we need to start with?
We need to know the blade load and cycle time!
Correct! Blade load can come from the manufacturer or field measurements. Cycle time includes both push and backtrack time, which depends on haul distance. Can anyone recall how we calculate push time?
It's based on the haul distance and speed, which we can find using the performance chart!
Exactly! Once we have that, we can calculate productivity in loose meter cubes per hour. Don't forget to factor in job efficiency; machines rarely work for a full hour. What does a typical job efficiency look like?
It can be anywhere from 30 to 50 minutes per hour depending on project conditions!
Well done! So, we must multiply the estimated productivity by this job efficiency to get a realistic figure.
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Now, let’s explore how to calculate the unit cost of production. What does this refer to?
It’s the cost per loose meter cube of earth moved!
Exactly right! To calculate unit cost, we need the hourly cost of the machine and its productivity. What are some components that contribute to the hourly cost?
Ownership costs, operating costs, and operator wages!
Perfect! Once we gather all those components and have our productivity figure, we can divide the hourly cost by productivity to find the unit cost of production.
And this is critical for project bidding, right?
Absolutely! Accurately estimating these costs is vital for your bidding strategy. Remember, underestimating costs can lead to serious financial issues down the line.
Overview
Short Summary
This section explores the cycle time, productivity estimation, and cost analysis involved in earthmoving operations, particularly focusing on bulldozer efficiency.
Medium Summary
The section discusses key elements of earthmoving operations, including cycle time components such as push time, backtrack time, and maneuver time. It elaborates on how to estimate productivity, considering factors like haul distance, material type, and operator efficiency. It emphasizes the importance of calculating unit cost of production for effective bidding.
Detailed Summary
In this section, we analyze the unit cost of production in earthmoving operations, particularly for bulldozers. Key components of cycle time are introduced, including push time, backtrack time, and maneuver time. Push time and backtrack time are categorized as variable times influenced by haul distance and operating speed, while maneuver time depends on the type of transmission. The section delves into how to estimate the bulldozer's productivity—expressed in loose meter cubes per hour—by assessing blade load and cycle time. Correction factors related to project conditions, operator skill, and material type are discussed in relation to production curves. The unit cost of production, defined as the cost per loose meter cube of moved earth, is calculated by dividing the hourly machine cost by productivity. This information is crucial for effective cost estimation and bidding strategy in construction projects.
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Create a free accountSo, this cutting and pushing will go together. So, the time required to push, backtrack and maneuver into position, so that is called as a cycle time of the bulldozer.
Detailed Explanation
Cycle time refers to the total time taken for a bulldozer to perform a complete set of operations which includes cutting the earth, pushing it, dumping it, and then returning to the starting position. This overall time is crucial for calculating productivity and cost in earthmoving operations.
Examples & Analogies
Imagine you are at a construction site using a toy bulldozer to push sand into a pile, then go back to pick up more sand. The time it takes to push the sand and return to the starting point is similar to the bulldozer’s cycle time.
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Create a free accountWe call this as fixed time, this is fixed time and this one is variable time, your push and backtrack it is called this variable time.
Detailed Explanation
In earthmoving operations, time can be categorized into fixed time and variable time. Fixed time includes tasks like maneuver adjustments, while variable time depends on factors like haul distance, which affects how long it takes to push dirt or return.
Examples & Analogies
Think of fixed time as the time it takes to put on your shoes before leaving a house, which doesn’t change much. In contrast, variable time is like how long it takes to walk to a bus stop, which can vary based on your walking speed and distance.
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Create a free accountSo, to know the push time and the backtrack time, I need to know the travel distance or the dozing distance or the haul distance.
Detailed Explanation
To calculate the push time (the time taken to push dirt) and backtrack time (the time taken to return), the haul distance must be known. Longer distances will result in longer times, and the speed of the bulldozer is also a crucial factor.
Examples & Analogies
If you’re carrying a heavy backpack to the school across a field, the distance you have to walk makes a big difference. A short 100-meter walk is quick, but a longer 1-kilometer walk takes significantly more time and effort.
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Create a free accountSo, what is this maneuver time? So, already I told you maneuver time is nothing, but the time needed for changing your speed accelerating, changing the gears.
Detailed Explanation
Maneuver time refers to the time taken to adjust the bulldozer’s speed or change gears. This time can vary based on the transmission type—manual versus automatic—impacting overall cycle time.
Examples & Analogies
Consider driving a car with a manual transmission versus an automatic. In the manual car, each time you want to accelerate or slow down takes a bit more time due to gear changes, while the automatic car shifts gears for you, allowing for smoother and faster adjustments.
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Create a free accountNow let us see how to estimate the productivity of the bulldozer. So, we are going to estimate the productivity a loose meter cube per hour.
Detailed Explanation
Estimating productivity involves determining how many loose cubic meters of earth can be moved by the bulldozer in an hour. This can help in budgeting and planning for construction or earthmoving projects.
Examples & Analogies
It’s like measuring how much sand you can move with a shovel. If you can fill a one-cubic-meter container in 30 minutes, you can estimate that you can move two cubic meters in an hour.
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Create a free accountThis is a very important because as I told you, when you prepare for bidding when you plan for bidding in unit rate work, in unit rate contract unit rate work.
Detailed Explanation
Calculating the unit cost of production involves dividing the total hourly cost of operating the bulldozer by its productivity. This calculation is essential for bidding rates on construction jobs.
Examples & Analogies
Think about running a lemonade stand. If the cost to make a pitcher of lemonade is 0.50. Similarly, in earthmoving, understanding how much it costs to move each cubic meter of earth helps in pricing and budgeting.
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Key concepts
Core takeaways and short definitions to help you quickly recall the key ideas from this section.
- Cycle Time:
The complete time needed for a bulldozer to finish a dozing operation.
- Maneuver Time:
Fixed time taken for gear changes or speed adjustments that varies with transmission type.
- Push and Backtrack Time:
Variable times dependent on haul distance and project conditions.
- Job Efficiency:
The actual productive time of the bulldozer during an hour.
- Unit Cost:
The cost per loose meter cube, critical for project bidding.
Examples
Step-by-step examples to apply the section's ideas and test your understanding.
If a bulldozer operates for 40 minutes in an hour and has a productivity of 100 loose meters cubed per hour, then the effective output is 66.67 loose cubic meters.
For a bulldozer with a 1.5-meter blade load and a cycle time of 2 minutes, the productivity would be calculated as 90 loose cubic meters per hour (blade load divided by cycle time).
Memory aids
Once upon a time, there was a bulldozer named Bulldo who had to push earth and then return back to his point. He learned that timing was everything — cutting, pushing, and maneuvering made him the fastest on the job site!
Remember the acronym 'P.B.M.' for 'Push, Backtrack, Maneuver' to recall the key components of cycle time.
Flash Cards
Glossary
Cycle Time
The total time taken by a bulldozer to complete a full sequence of operations, including push, backtrack, and maneuvering.
Push Time
The time required for the bulldozer to push earth during its operation.
Backtrack Time
The time needed for the bulldozer to return to its original position after dumping the earth.
Maneuver Time
The time taken for operational adjustments such as changing gears or altering speed.
Blade Load
The volume of earth that the bulldozer's blade can carry during operation.
Job Efficiency
The actual working time of the bulldozer in a given hour, expressed as a fraction of 60 minutes.
Unit Cost
The cost incurred for moving one loose meter cube of earth, calculated as hourly cost divided by productivity.