Podcast
Questions and Answers
What is the primary concern in earthwork for roadway design?
What is the primary concern in earthwork for roadway design?
What is the manual method for determining earth excavation and embankment amounts?
What is the manual method for determining earth excavation and embankment amounts?
What is the purpose of a mass diagram?
What is the purpose of a mass diagram?
What does a rising curve on a mass diagram indicate?
What does a rising curve on a mass diagram indicate?
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What is the purpose of a balance line on a mass diagram?
What is the purpose of a balance line on a mass diagram?
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What is the term used for the area in cut or fill in a section?
What is the term used for the area in cut or fill in a section?
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What is plotted below a profile of the route in a mass diagram?
What is plotted below a profile of the route in a mass diagram?
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What is the purpose of creating cross sections of the proposed highway and original ground cross sections?
What is the purpose of creating cross sections of the proposed highway and original ground cross sections?
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Study Notes
Earthwork in Roadway Design
- Earthwork includes excavation of existing earth material and placement of fill material for constructing embankments.
- The manual method for determining earth excavation and embankment amounts involves three steps:
- Placing cross sections of the proposed highway on original ground cross sections
- Calculating areas in cut and fill
- Computing volumes between sections
Cut and Fill
- Cut and fill refer to areas in a section, while excavation and embankment refer to volumes.
- Methods for manually calculating cut and fill areas are presented in most surveying textbooks.
Mass Diagrams
- Mass diagrams (or mass-haul diagrams) are plots of cumulative volumes of cut and fill along an alignment.
- The diagram is typically plotted below a profile of the route, with the ordinate at any station representing the sum of volumes of cut and fill up to that station.
- The rising curve on the mass diagram indicates excavation, while a descending curve indicates embankment.
Balance Line
- A horizontal line drawn to intersect the mass diagram at two points indicates equal excavation and embankment (adjusted for shrinkage) between the two stations represented by the points of intersection.
- Such a horizontal line is called a balance line, because the excavation balances the embankment between the two points at its ends.
Economics of Earthwork Distribution
- The most economical way to handle the distribution of earthwork volumes can be determined from the mass diagram.
- Highway engineers strive to balance the amount of cut and fill during a highway construction project to avoid costly hauling of materials.
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Description
Learn about earthwork calculation in roadway design, including excavation and placement of fill material, and the manual method for determining earth excavation and embankment amounts.
