DR. Nabil Dmaidi

ESTIMATING EARTHWORK

ESTIMATING EARTHWORK

DR. Nabil Dmaidi

Estimating Earthwork

Earthwork includes: 1. Excavation 2. Grading: Moving earth to change elevation 3. Temporary shoring 4. Back fill or fill: Adding earth to raise grade 5. Compaction: Increasing density 6. Disposal

DR. Nabil Dmaidi

Productivity FactorsProductivity Factors

A. Job conditions– Material type– Water level and moisture content– Job size– Length of haul– Haul road condition (accessibility and load

restrictions)

DR. Nabil Dmaidi

Productivity Factors (cont.)Productivity Factors (cont.)

B. Management conditions– Equipment conditions and maintenance

practices– Skills of work force and management– Planning, supervision and coordination of

work.

DR. Nabil Dmaidi

Job Efficiency Factors for Earthmoving OperationsJob Efficiency Factors for Earthmoving Operations

J ob Conditions** Excellent Good Fair Poor

Excellent 0.84 0.81 0.76 0.70

Good 0.78 0.75 0.71 0.65

Fair 0.72 0.69 0.65 0.60

Poor 0.63 0.61 0.57 0.52

Management Conditions*

DR. Nabil Dmaidi

Units of Measure Units of Measure Cubic Yard (bank, loose, or compacted)

Bank (BCY): Material 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

DR. Nabil Dmaidi

1.0

1.25

0.90

1.0 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 place CompactedLoose

DR. Nabil Dmaidi

VolumeVolumeBank: VB

– Bank cubic yards (BCY)– Density B Lb /BCY

Loose: Vl

– Loose cubic yards (LCY)– Density L Lb/LCY

Compacted: Vc

– Compacted cubic yards (CCY)– Density C LB/CCY

DR. Nabil Dmaidi

Swell:A soil increase in volume when it is excavated.

Swell (%) = ( - 1) x 100

Load factor =

Bank Volume = Loose volume x Load factor

Loose densityBank density

Bank densityLoose density

DR. Nabil Dmaidi

Shrinkage:

A soil decreases in volume when it is compacted

Shrinkage (%) = (1 - ) x 100

Shrinkage factor = 1 - Shrinkage

Compacted volume

= Bank volume x Shrinkage factor

Bank densityCompacted density

DR. Nabil Dmaidi

Approximate Material CharacteristicsApproximate Material Characteristics

MaterialLoose (lb/cy)

Bank (lb/cy)

Swell (%)

Load Factor

Clay, dry 2,100 2,650 26 0.79Clay, wet 2,700 3,575 32 0.76Clay and gravel, dry 2,400 2,800 17 0.85Clay and gravel, wet 2,600 3,100 17 0.85Earth, dry 2,215 2,850 29 0.78Earth, moist 2,410 3,080 28 0.78Earth, wet 2,750 3,380 23 0.81Gravel, wet 2,780 3,140 13 0.88Gravel, dry 3,090 3,620 17 0.85Sand, dry 2,600 2,920 12 0.89Sand, wet 3,100 3,520 13 0.88Sand and gravel, dry 2,900 3,250 12 0.89Sand and gravel, wet 3,400 3,750 10 0.91

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

DR. Nabil Dmaidi

Typical Soil Volume Conversion FactorsTypical Soil Volume Conversion Factors

InitialSoil Type Soil Condition Bank Loose Compacted

Clay Bank 1.00 1.27 0.90Loose 0.79 1.00 0.71Compacted 1.11 1.41 1.00

Common earth Bank 1.00 1.25 0.90Loose 0.80 1.00 0.72Compacted 1.11 1.39 1.00

Rock (blasted) Bank 1.00 1.50 1.30Loose 0.67 1.00 0.87Compacted 0.77 1.15 1.00

Sand Bank 1.00 1.12 0.95Loose 0.89 1.00 0.85Compacted 1.05 1.18 1.00

Convrted to:

DR. Nabil Dmaidi

Estimating Earth work for Trenches and FoundationsEstimating Earth work for Trenches and Foundations

Angle of Repose2’-0”or more

DR. Nabil Dmaidi

Approximate Angle of ReposeApproximate Angle of ReposeFor Sloping Sides of Excavation

OriginalGround Line

Solid

Rock

, Sla

te o

r C

em

ente

d S

and a

nd G

ravel

(90

Deg.)

Com

pact

ed A

ngul

ar G

rave

ls

1/2:

1 (6

3 D

eg.)

Reco

mm

ende

d Sl

ope

for A

vera

ge S

oils

1:1

(45

Deg.)

Compacted Sharp

Sand

1 1/2 :1 (3

3 Deg.)

Well Rounded Loose Sand

2:1 (26 Deg.)

DR. Nabil Dmaidi

Calculating Earthwork QuantitiesCalculating Earthwork Quantities

1.End Area Method

2.Contour Line/ Grid Method

DR. Nabil Dmaidi

1. End Area Method1. End Area Method

Used in sites where length is much greater than width

DR. Nabil Dmaidi

CALCULATING EARTHWORK QUANTITIESCALCULATING EARTHWORK QUANTITIES

1. End Area Methoda. 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.

DR. Nabil Dmaidi

Project Site Showing 100 StationsProject Site Showing 100 Stations

Fill

Cut

80

82

84

86

88

80

84

86

88

82

78

A’ B’ C’ D’ E’ F’

A B C D E F100' 100' 100' 100' 100'

500'

30

0'

DR. Nabil Dmaidi

80

78

76

82

80

78

84

82

80

86

84

88

86

90

88

78.5

80.3

82.3

84.2

86.2

88.2

Sec. A’- A

Sec. B’- B

Sec. C’- C

Sec. D’- D

Sec. E’- E

Sec. F’- F

Pro

ject

Cro

ss S

ect

ion

s

DR. Nabil Dmaidi

Cross-Section @ A’- ACross-Section @ A’- A

80

79

78

77

76

79.5

78.5

76.7

Section A’- A

Area = = 173.7193 x 1.8

2

Area = = 53.5107 x 1.0

2

DR. Nabil Dmaidi

Cross-Section @ B’- BCross-Section @ B’- B

82

81

80

79

78

81.8

80.3

76.7

Section B’- B

Area = = 189.0210 x 1.8

2

Area = = 67.590 x 1.5

2

DR. Nabil Dmaidi

Table 1. Cumulative Earthwork Quantities Table 1. Cumulative Earthwork Quantities

Section

Emb (CCY)

Exc. (BCY)

Exc. x c (CCY) C= 0.9

Net Exc. (CCY)

Cum Exc (CCY)

A-B 672 224 202 - 470 - 470 B-C 567 441 397 - 170 - 640 C-D 215 791 712 497 - 143 D-E 0 1031 928 928 785 E-F 0 1222 1100 1100 1885

DR. Nabil Dmaidi

2. Contour Line/ Grid Method2. Contour Line/ Grid Method

Used for parking lots and site “leveling” Grid size from 10’x10’ to 50’x50’ the greater the terrain variance the smaller

the grid

DR. Nabil Dmaidi

2. CONTOUR LINE/GRID CELL METHOD(cont.)2. CONTOUR LINE/GRID CELL METHOD(cont.)Step l

Determine 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.

DR. Nabil Dmaidi

A B C D E F87.6 88.6 89.4 90.4 91.6 93.2

G H J K L M87.4 88.2 89.5 90.6 91.6 92.7

N O P Q R S87.2 87.7 89.0 90.4 91.3 92.0

87.6 88.5 89.3 90.3 91.5 95.0

94.3

93.5

93.1

A B C D E F G300’

88’ 89’ 90’ 91’ 92’ 93’ 94’

No ScaleNotes:1. Bring the entire site to elevation 90.2. All grids are 50’x 50’ = 2500 sq. ft.3. Present contours

DR. Nabil Dmaidi

PurposeGrade the entire site to grade 90’

Quick and DirtyAssume one gridExisting 90.50Proposed 90.00Cut 0.50

Total Cost =

= 833CY150 x 300 x 0.5027

300'

15

0'Need

FillNeedCut

90'

90' 91'

90.5'

DR. Nabil Dmaidi

Average elevation

=

= 88.08

change= 90-88.08

= 1.92

cut =

= 177.77 CY

and so on.

If we choose the grid size to be 50’x50’

87.6+88.5+87.6+88.64

87.6

88.6

87.687.6