Planning for Earthwork Construction Chapter 3 Planning for Earthwork Construction Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Planning for Earthwork Construction Every construction project is a unique undertaking. Therefore, planning is undertaken to understand the problems and to develop courses of action.

Planning Earthwork Construction Review the Contract Documents Study the plans Plan the Work Perform quantity take-off Determine costs

Planning Earthwork Construction A site visit is strongly recommended to relate the physical site characteristics to the work details.

Planning Earthwork Construction After the site visit is completed, the planner determines the quantity of materials that will have to be furnish or move. The takeoff or "quantity survey."

Quantity Take-off available engineering and design data. Must be as accurate as possible, and should be based on all available engineering and design data.

Planning Earthwork Construction During the takeoff, the planner must make decisions concerning: equipment needs sequence of operations and crew size

Graphical Presentation of Earthwork Three kinds of views are presented in the contract documents to show earthwork construction features: Plan view Profile view Cross section view

Plan View The plan view is looking down on the proposed work and presents the horizontal alignment of features Figure 13.1 | Plan view of a highway project. What does P.C. mean?

Profile View The profile view is a cut view typically along the centerline of the work. It presents the vertical alignment of features.

Cross Section View A view formed by a plane cutting the work at a right angle to its long axis When the ground surface is regular, sections are typically taken at every full station (100 ft) When the ground is irregular, sections must be taken at closer intervals & at points of change

Cross section for a fill (left side) Cross section for a fill (left side) Cross section for a cut (right side) Figure 13.3 | Earthwork cross sections.

Earthwork Quantities Calculation of earthwork volumes Earthwork computations involve: Calculation of earthwork volumes Balancing of cuts and fills Planning of the most economical material hauls.

End-Area Determination Most organizations use commercial computer software and digitizing tablets to calculate cross section end areas. www.trimble.com/paydirt.html www.agtek.com/about.shtm

End-Area Determination Other methods include the use of a planimeter, subdivision of the area into geometric figures with definite formulas for areas (rectangles, triangles, parallelograms and trapezoids), and the use of the trapezoidal formula.

Trapezoidal Computations If the calculations must be made by hand, the area formula for a triangle and a trapezoid are used to compute the volume. Area of a triangle = ½ hw Area of a trapezoid =

General Trapezoidal Formula Area =

Average End Area Method Volume [net cy] = Assumes that the ground between the two end areas changes in a linear fashion. The principle is that the volume of the solid bounded by two parallel, or nearly parallel, cross sections is equal to the average of the two end areas times the distance between the cross sections along their centerline

Average End Area Figure 13.5 | Volume between two end areas

Average End Area Figure 13.5 | Volume between two end areas

Average End Area Figure 13.5 | Volume between two end areas

Net Volume Bank cubic yards (bcy) Loose cubic yards (lcy) Compacted cubic yards (ccy) lcy ccy bcy

Mass Diagram Earthmoving is basically an operation where material is removed from high spots and deposited in low spots with the “making up” of any deficit with borrow or the wasting of excess cut material.

Mass Diagram The mass diagram is an excellent method of analyzing linear earthmoving operations. It is a graphical means for measuring haul distance (stations) in terms of earthwork volume (cubic yards).

Mass Diagram Aids in identifying: Where to utilize specific types of equipment, Where quantities of material are required, Average haul distance, Haul grades.

Earthwork Volume Calculation Sheet An earthwork volume sheet, can easily be constructed using a spreadsheet program. It permits a systematic recording of information and completing the necessary earthwork calculations

Earthwork Volume Calculation Sheet Table 3.1, page 73

Stations. Column 1 is a listing of all stations at which cross-sectional areas have been recorded.

Area of cut. Column 2 is the cross-sectional area of the cut at each station. Usually this area must be computed from the project cross sections.

Area of fill. Column 3 is the cross-sectional area of the fill at each station. Usually this area must be computed from the project cross sections. Note there can be both cut and fill at a station.

Volume of cut. Column 4 is the volume of cut between the adjacent preceding station and the station. This is a bank volume.

Volume of fill. Column 5 is the volume of fill between the adjacent preceding station and the station. The average-end-area formula, This is a compacted volume.

STRIPPING For cut sections subtract the stripping.

STRIPPING For fill sections the stripping is a cut quantity; plus an equal amount must be added to the embankment quantity.

Column 6 is the stripping volume of topsoil over the cut between the adjacent preceding station and the station. This represents a bank volume of cut material. Topsoil material is not suitable for use in the embankment. This volume is commonly calculated by multiplying the distance between stations or fractions of stations by the width of the cut. This provides the area of the cut footprint. The footprint area is then multiplied by an average depth of topsoil to derive the stripping volume. The average depth of topsoil must be determined by field investigation.

Column 7 is the stripping volume of topsoil under the fill between the adjacent preceding station and the station. The stripping is a bank volume but it also represents an additional requirement for fill material, compacted volume of fill. This volume is commonly calculated by multiplying the distance between stations or fractions of stations by the width of the cut. This provides the area of the cut footprint. The footprint area is then multiplied by an average depth of topsoil to derive the stripping volume. The average depth of topsoil must be determined by field investigation.

Column 8 is the total volume of cut material available for use in embankment construction. It is derived by subtracting the cut stripping (column 6) from the cut volume (column 4), both are bank volume quantities.

Column 9 is the total volume of fill required Column 9 is the total volume of fill required. It is derived by adding the fill stripping (column 7) to the fill volume (column 5), both are compacted volume quantities.

Column 10 is the total fill volume converted from compacted volume to bank volume

Column 11 is the difference between column 10 and column 8 Column 11 is the difference between column 10 and column 8. This indicates the volume of material that is available (cut is positive) or required (fill is negative) within station increments after intrastation balancing.

Mass Ordinate Column 12 is the running total of column 11 values from some point of beginning on the project profile.

MASS DIAGRAM PLOTTING Volume scale (cy) Horizontal scale (stations) 1000 500 Volume scale (cy) - 500 - 1000 ON OUR MASS DIAGRAM SHEETS THE BOTTOM SECTION IS THE ACTUAL MASS DIAGRAM. THE UPPER PORTION CONTAINS A PROFILE VIEW SHOWING THE PLOTTED ELEVATIONS AT CENTERLINE OF THE PROPOSED CONSTRUCTION AND THE EXISTING TERRAIN. WE WILL USE THIS PROFILE TO ASSIST US IN DETERMINING AVERAGE PERCENT OF GRADE OUR EQUIPMENT WILL BE OPERATING ON. LETS LOOK IN DETAIL AT THE BOTTOM SECTION. ALONG THE ENTIRE BOTTOM OF OUR SHEET RUNS OUR HORIZONTAL SCALE WHICH IS OUR STATION NUMBERS, THIS IS THE ONLY THING OUR MASS DIAGRAM AND PROFILE VIEW SHARE, A COMMON REFERENCE INDICATOR. TO THE LEFT IS OUR VOLUME SCALE, REPRESENTING AMOUNTS OF MATERIAL IN COMPACTED CUBIC YARDS. 0 + 00 1 + 00 2 + 00 3 + 00 4 +00 5 + 00 6 + 00 Horizontal scale (stations)

MASS DIAGRAM PLOTTING STATION 0+50 - 138 CY 1000 500 - 500 - 1000 - 500 - 1000 REFER BACK TO YOUR EARTHWORK VOLUME SHEETS FROM THE PRACTICAL EXERCISE. WE WILL USE THE INFORMATION FROM COLUMNS 1 (STATION NUMBER) AND 12 (MASS ORDINATE) TO PLOT OUR MASS DIAGRAM. AT STATION 1+00 WE HAD A MASS ORDINATE OF - 191 CCYS OF MATERIAL. FIND STATION NUMBER 1+00 ON THE BOTTOM HORIZONTAL SCALE. FOLLOW THIS LINE UP TO THE ZERO BALANCE LINE FOR VOLUME (LEFT HAND SCALE) IF WE ARE AT ZERO AND OUR NUMBER TO PLOT IS A NEGATIVE THEN WE KNOW WE MUST WORK BELOW THE ZERO LINE TO PLOT THIS REQUIREMENT. EACH LINE ON OUR SHEET REPRESENTS 50 CCYS OF MATERIAL WHEN USING OUR VOLUME SCALE, SO IF WE ARE GOING TO PLOT A VOLUME OF 191CCYS WE WOULD GO DOWN TO ALMOST TO THE FORTH LINE AND MAKE A DOT. WE HAVE JUST PLOTTED OUR FIRST STATION. 0 + 00 1 + 00 2 + 00 3 + 00 4 +00 5 + 00 6 + 00

MASS DIAGRAM PLOTTING STATION 1 +00 - 405 CY 1000 500 - 500 - 1000 - 500 - 1000 YOU WOULD THEN PLOT YOUR REMAINING STATIONS IN A SIMILAR FASHION. 0 + 00 1 + 00 2 + 00 3 + 00 4 +00 5 + 00 6 + 00

MASS DIAGRAM PLOTTING STATION 3 +50 518 CY 1000 500 - 500 - 1000 - 500 - 1000 0 + 00 1 + 00 2 + 00 3 + 00 4 +00 5 + 00 6 + 00

MASS DIAGRAM PLOTTING CONNECT THE POINTS 1000 500 - 500 - 1000 0 + 00 - 500 - 1000 0 + 00 1 + 00 2 + 00 3 + 00 4 +00 5 + 00 6 + 00

MASS DIAGRAM Descending lines 1000 Embankment requirements exceeds excavation quantity. 500 -500 WHEN OUR LINE GOES DOWN THIS IS SHOWING US FILL SECTIONS (REMEMBER I FILL DOWN) - 1000 Descending lines 0 + 00 1 + 00 2 + 00 3 + 00 4 +00 5 + 00 6 + 00

MASS DIAGRAM Ascending lines 1000 Ascending lines 500 -500 LINES ON OUR MASS DIAGRAM EITHER GO UP OR DOWN. IF THE LINE GOES UP THIS IS A REPRESENTATION OF CUTTING MATERIAL (THINK UPPER CUT) - 1000 Excavation exceeds embankment requirements 0 + 00 1 + 00 2 + 00 3 + 00 4 +00 5 + 00 6 + 00

MASS DIAGRAM ONCE AGAIN A NODE IS A EQUAL BALANCE OF MATERIAL BEING CUT AS THAT IS REQUIRED FOR FILL.

MASS DIAGRAM Zero balance line Excavation quantity equals 1000 500 Zero balance line -500 LETS TALK SOME MORE ABOUT OUR ZERO BALANCE LINE. EVERY TIME THE LINE THAT WE JUST DREW (CALLED THE MASS DIAGRAM) CROSSES THE ZERO BALANCE LINE THERE IS EXACTLY AS MUCH MATERIAL FILLED AS THERE IS CUT, OR A ZERO BALANCE OF EXCESS OR DEFICIT MATERIAL AT THAT POINT. - 1000 Excavation quantity equals embankment requirement. 0 + 00 1 + 00 2 + 00 3 + 00 4 +00 5 + 00 6 + 00

MASS DIAGRAM Maximum is where the cut transitions into fill. Maximum and minimum points Maximum is where the cut transitions into fill. Minimum is where the fill transitions into cut.

MASS DIAGRAM Transition point Maximum and minimum points 1000 500 -500 -500 WHEN OUR LINE STOPS GOING ONE DIRECTION AND STARTS GOING ANOTHER THIS IS CALLED A TRANSITION POINT. BECAUSE WE ARE TRANSITIONING FROM FILL TO CUT. OR VISA - VERSA - 1000 Transition point 0 + 00 1 + 00 2 + 00 3 + 00 4 +00 5 + 00 6 + 00

MASS DIAGRAM Final position 410 cy waste 90 cy Stations borrow 500 cy 0 1 2 3 4 5 6 7 90 cy borrow Stations Above the zero line indicates waste. Below the zero line indicates borrow.

MASS DIAGRAM Descending lines? Crossing the zero volume line? Is a graphical means for measuring haul in terms of station yards. Ascending lines? Descending lines? Crossing the zero volume line? Max. and min. points? Final position?

A mass diagram is a running total of the quantity of material that is surplus or deficient along the project profile. An excavation operation produces an ascending mass diagram curve; the excavation quantity exceeds the embankment quantity requirements. Excavation is occurring between stations A and B, and stations D and E in Fig. 13.6. The total volume of excavation between A and B is obtained by projecting horizontally to the vertical axis the mass diagram line points at stations A and B and reading the difference of the two volumes. Conversely, if the operation is a fill situation, there is a deficiency of material and a descending curve is produced; the embankment requirements exceed the excavation quantity being generated. Filling is occurring between stations B and D. The volume of fill can be determined in a manner similar to the excavation examination by a projection of the mass diagram line points to the vertical scale. The maximum or minimum points on the mass diagram, where the curve transitions from rising to falling or falling to rising, indicate a change from an excavation to fill situation or vice versa. These points are referred to as transition points. On the ground profile, the grade line is crossing the ground line (see Fig. 13.6 at station B and D). When the mass diagram curve crosses the datum (or zero volume) line (as at station C) exactly as much material is being excavated (between stations A and C) as is required for fill between B and C. There is no excess or deficit of material at that point in the project. The final position of the mass diagram curve above or below the datum line indicates whether the project has surplus material that must be wasted or if there is a deficiency which must be made up by borrowing material from outside the project limits. Figure 13.6 station E indicates a waste situation and excess material will have to be removed from the project.

Economical Haul Distances Machine type Economical haul distance Large dozers, pushing material Up to 300 ft Push-loaded scrapers 300 to 5,000 ft Trucks > than 5,000 ft Table 13.2 | Economical haul distances based on basic machine types

Mass Diagram With a Balance Line Figure 13.7 | Mass diagram with a balance line. If the curve is above the balance line, the direction of haul is from left to right, i.e., up stationing. When the curve is below the balance line the haul is from right to left, i.e., down stationing.

Haul Distances Page 81

Haul Distances Average haul = area / quantity (cy) Haul No. 3 quantity -17,080 Haul No. 1 quantity?

Haul Distance

Haul Distance Area under diagram Average haul No. 3 stations

Consolidated Average Hauls Using the individual average hauls and the quantity associated with each, a project average haul can be calculated. Consider the three hauls and their sum of vertical’s average haul distances. By multiplying each haul quantity by its respective haul distance a station-yard value can be determined.

Consolidated Average Hauls Stations Haul 1 11,459 bcy 3+51 40,221 sta-cy Haul 2 5,590 bcy 3+35 18,727 sta-cy Haul 3 17,080 bcy 12+51 213,654 sta-cy 34,129 bcy 272,602 sta-cy 272,602 sta-cy = 8.0 stations 34,129 bcy

Consolidated Average Hauls Stations Haul 1 11,459 bcy 3+51 40,221 sta-cy Haul 2 5,590 bcy 3+35 18,727 sta-cy 17,049 bcy 58,948 sta-cy 58,948 sta-cy = 3.5 stations 17,049 bcy Haul 3 17,080 bcy 12.5 stations

Pricing Earthwork Operations The cost of earthwork operations will vary with the kind of soil or rock encountered and the methods used to excavate, haul, and place the material in its final deposition.

Spreading Dumped Embankment Material with a Dozer

Water Truck and Roller used to Compaction Embankment Material

Three-link Earthwork System Spread & compact Excavate & load Haul, dump, return