ESTIMATING EARTHWORK

Prof Awad S. Hanna

Estimating EarthworkEarthwork includes:1.Excavation2.Grading: Moving earth to change elevation3.Temporary shoring4.Back fill or fill: Adding earth to raise grade5.Compaction: Increasing density6.Disposal

Prof Awad S. Hanna

Productivity FactorsA. Job conditionsMaterial typeWater level and moisture contentJob sizeLength of haulHaul road condition (accessibility and load restrictions)

Prof Awad S. Hanna

Productivity Factors (cont.)B. Management conditionsEquipment conditions and maintenance practicesSkills of work force and managementPlanning, supervision and coordination of work.

Prof Awad S. Hanna

Job Efficiency Factors for Earthmoving Operations

Prof Awad S. Hanna

Sheet1

Management Conditions*

Job Conditions**ExcellentGoodFairPoor

Excellent0.840.810.760.70

Good0.780.750.710.65

Fair0.720.690.650.60

Poor0.630.610.570.52

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Units of MeasureCubic Yard (bank, loose, or compacted)

Prof Awad S. Hanna

Sheet1

Bank (BCY):Materials in its natural state before disturbance (in-place, in-situ)

Loose (LCY):Material that has been compacted or disturbed or loaded

Compacted (CCY):Material after compaction

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1.01.250.901.0 CUBIC YARD IN NATURAL CONDITION (IN-PLACE YARD)1.25 CUBIC YARD AFTER DIGGING (LOOSE YARDS)0.90 CUBIC YARD AFTER COMPACTED (COMPACTED YARDS)In placeCompactedLoose

Prof Awad S. Hanna

VolumeBank: VBBank cubic yards (BCY)Density B Lb /BCY

Loose: VlLoose cubic yards (LCY)Density L Lb/LCY

Compacted: VcCompacted cubic yards (CCY)Density C LB/CCY

Prof Awad S. Hanna

Swell:A soil increase in volume when it is excavated.Swell (%) = ( - 1) x 100

Load factor =

Bank Volume = Loose volume x Load factorLoose densityBank densityBank densityLoose density

Prof Awad S. Hanna

Shrinkage:A soil decreases in volume when it is compactedShrinkage (%) = (1 - ) x 100

Shrinkage factor = 1 - ShrinkageCompacted volume= Bank volume x Shrinkage factorBank densityCompacted density

Prof Awad S. Hanna

Approximate Material CharacteristicsExact values will vary with grain size, moisture content, compaction, etc. Test to determine exact values for specific soils.

Prof Awad S. Hanna

Sheet1

MaterialLoose (lb/cy)Bank (lb/cy)Swell (%)Load Factor

Clay, dry2,1002,650260.79

Clay, wet2,7003,575320.76

Clay and gravel, dry2,4002,800170.85

Clay and gravel, wet2,6003,100170.85

Earth, dry2,2152,850290.78

Earth, moist2,4103,080280.78

Earth, wet2,7503,380230.81

Gravel, wet2,7803,140130.88

Gravel, dry3,0903,620170.85

Sand, dry2,6002,920120.89

Sand, wet3,1003,520130.88

Sand and gravel, dry2,9003,250120.89

Sand and gravel, wet3,4003,750100.91

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Typical Soil Volume Conversion Factors

Prof Awad S. Hanna

Sheet1

MaterialLoose (lb/cy)Bank (lb/cy)Swell (%)Load Factor

Clay, dry2,1002,650260.79

Clay, wet2,7003,575320.76

Clay and gravel, dry2,4002,800170.85

Clay and gravel, wet2,6003,100170.85

Earth, dry2,2152,850290.78

Earth, moist2,4103,080280.78

Earth, wet2,7503,380230.81

Gravel, wet2,7803,140130.88

Gravel, dry3,0903,620170.85

Sand, dry2,6002,920120.89

Sand, wet3,1003,520130.88

Sand and gravel, dry2,9003,250120.89

Sand and gravel, wet3,4003,750100.91

InitialConvrted to:

Soil TypeSoil ConditionBankLooseCompacted

ClayBank1.001.270.90

Loose0.791.000.71

Compacted1.111.411.00

Common earthBank1.001.250.90

Loose0.801.000.72

Compacted1.111.391.00

Rock (blasted)Bank1.001.501.30

Loose0.671.000.87

Compacted0.771.151.00

SandBank1.001.120.95

Loose0.891.000.85

Compacted1.051.181.00

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Estimating Earth work for Trenches and FoundationAngle of Repose2-0or more

Prof Awad S. Hanna

Approximate Angle of ReposeFor Sloping Sides of ExcavationOriginalGround LineSolid Rock, Slate or Cemented Sand and Gravel(90 Deg.)Compacted Angular Gravels1/2:1 (63 Deg.)Recommended Slope for Average Soils1:1 (45 Deg.)Compacted Sharp Sand1 1/2 :1 (33 Deg.)Well Rounded Loose Sand2:1 (26 Deg.)

Prof Awad S. Hanna

Calculating Earthwork Quantities1.End Area Method2.Contour Line/ Grid Method

Prof Awad S. Hanna

1. End Area MethodUsed in sites where length is much greater than width

Prof Awad S. Hanna

CALCULATING EARTHWORK QUANTITIES1. End Area Method

a.Take cross-sections at regular intervals, typically, 100 intervals.

b.Calculate the cross-section end areas

c.The volume of earthwork between sections is obtained by taking the average of the end areas at each station in square feet multiplied by the distance between sections in feet and dividing by 27 to obtain the volume in cubic yards.

Prof Awad S. Hanna

Project Site Showing 100 StationsFillCut8082848688808486888278ABCDEFABCDEF100'100'100'100'100'500'300'

Prof Awad S. Hanna

80787682807884828086848886908878.580.382.384.286.288.2Sec. A- ASec. B- BSec. C- CSec. D- DSec. E- ESec. F- FProject Cross Sections

Prof Awad S. Hanna

Cross-Section @ A- A807978777679.578.576.7Section A- AArea == 173.7193 x 1.82Area == 53.5107 x 1.02

Prof Awad S. Hanna

Cross-Section @ B- B828180797881.880.376.7Section B- BArea == 189.0210 x 1.82Area == 67.590 x 1.52

Prof Awad S. Hanna

Table 1. Cumulative Earthwork Quantities

Prof Awad S. Hanna

Section

Emb (CCY)

Exc. (BCY)

Exc. x B/C (CCY)

Net Exc. (CCY)

Cum Exc (CCY)

A-B

672

224

254

- 418

- 418

B-C

567

441

499

- 68

- 486

C-D

215

791

896

681

195

D-E

0

1031

1167

1167

1362

E-F

0

1222

1384

1384

2746

2. Contour Line/ Grid MethodUsed for parking lots and site levelingGrid size from 10x10 to 50x50the greater the terrain variance the smaller the grid

Prof Awad S. Hanna

2. CONTOUR LINE/GRID CELL METHOD(cont.)Step lDetermine by visual study of the site drawing if the net total will be an import (more fill required than cut) an export (less fill required than cut) or a blend (cut and fill about equal)

Step 2Determine the pattern of calculation points or grid size.

Step 3 Determine elevations at each calculation location, the corners of each grid.

Step 4 Calculate the cubic yards of cut or fill required in each grid cell.

Step 5Add the individual Grid Cell quantities together to arrive at the total cut, total fill volume and the import or volume export yardage required for the job.

Prof Awad S. Hanna

ABCDEF87.688.689.490.491.693.2GHJKLM87.488.289.590.691.692.7NOPQRS87.287.789.090.491.392.087.688.589.390.391.595.094.393.593.1ABCDEFG30088899091929394No ScaleNotes:1. Bring the entire site to elevation 90.2. All grids are 50x 50 = 2500 sq. ft.3. Present contours

Prof Awad S. Hanna

PurposeGrade the entire site to grade 90

Quick and DirtyAssume one gridExisting90.50Proposed90.00Cut 0.50Total Cost = = 833CY150 x 300 x 0.5027300'150'NeedFillNeedCut90'90'91'90.5'

Prof Awad S. Hanna

Average elevation== 88.08change= 90-88.08= 1.92cut== 177.77 CYand so on.If we choose the grid size to be 50x5087.6+88.5+87.6+88.6487.688.687.687.6

Prof Awad S. Hanna

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