Chapter 7 Land Clearing (pdf) - HDRE, Inc
Chapter 7 Land Clearing (pdf) - HDRE, Inc
Chapter 7 Land Clearing (pdf) - HDRE, Inc
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<strong>Chapter</strong> 7<br />
Dozers<br />
Copyright © The McGraw-Hill Companies, <strong>Inc</strong>. Permission required for reproduction or display.
LAND CLEARINGS<br />
<strong>Clearing</strong> of vegetation and trees is<br />
usually necessary before excavating and<br />
embankment operations.<br />
Trees, brush, and even grass make<br />
material handling very difficult. If these<br />
organic materials are allowed to become<br />
mixed into an embankment fill, their<br />
decay over time will cause settlement of<br />
the fill.
LAND CLEARINGS<br />
Crawler dozers<br />
equipped with<br />
special clearing<br />
blades are<br />
excellent<br />
machines for<br />
land clearing.
LAND CLEARINGS<br />
Specification may allow<br />
shearing of the vegetation and<br />
trees at the ground line or it<br />
may be necessary to grub --<br />
remove stumps and roots from<br />
below the ground surface.
CLEARING BLADES<br />
<strong>Clearing</strong> blades are equipped with a<br />
flat sole which allows the blade to<br />
float on top of the ground without<br />
digging in.<br />
Flat sole
CLEARING BLADE
LAND CLEARINGS<br />
PRODUCTION ESTIMATES<br />
Tree-Count Method, using the<br />
Rome Plow Company’s formulas:<br />
With these formulas the production<br />
for the two operations<br />
1) cutting (equ. 7.9) and<br />
2) piling (equ. 7.10)<br />
are calculated separately.
LAND CLEARINGS<br />
PRODUCTION ESTIMATES<br />
Many variables can affect clearing<br />
work so all formula driven<br />
estimates should be tempered with<br />
consideration of:<br />
aUnderfoot conditions<br />
aVegetative growth<br />
aJob specifications
LAND CLEARINGS<br />
PRODUCTION ESTIMATES<br />
Underfoot conditions<br />
Grade and terrain greatly affect<br />
the operation of equipment.<br />
Consider: ♠ Sloping land<br />
♠ Embedded rocks<br />
♠ Stony outcroppings
Vegetative growth<br />
Consider:<br />
LAND CLEARINGS<br />
PRODUCTION ESTIMATES<br />
Tree size<br />
Tree count<br />
Wood density<br />
Roots & root mat<br />
Vines & undergrowth
LAND CLEARINGS<br />
PRODUCTION ESTIMATES<br />
Job specifications<br />
Consider: Logging Logging<br />
Grubbing<br />
Debris disposal
LAND CLEARINGS<br />
PRODUCTION ESTIMATES<br />
Tree-Count Method, requires a<br />
detailed reconnaissance and a<br />
tree count.<br />
Step 1. Size of area (in acres)<br />
Step 2. Size and number of<br />
dozers available
LAND CLEARINGS<br />
PRODUCTION ESTIMATES<br />
Tree-Count Method<br />
Step 3. Determine the average<br />
number of each size tree<br />
on a per acre basis.<br />
This will require a field reconnaissance.
LAND CLEARINGS<br />
PRODUCTION ESTIMATES<br />
Tree-Count Method<br />
Step 4. Basic production factors<br />
Table 7.3<br />
Step 5. Calculate time to clear<br />
one acre, equ. 7.9<br />
Step 6. Calculate total time
LAND CLEARINGS<br />
PRODUCTION ESTIMATES<br />
The Tree-Count Method has no<br />
correction factors for efficiency<br />
or for operator skill.<br />
The values in Table 7.3 are<br />
based on normal efficiency and<br />
average operator skill.
LAND CLEARINGS<br />
Size of area (in acres)<br />
Acres to be cleared =<br />
width (ft) ×<br />
length (ft)<br />
43,560 sq ft per acre
LAND CLEARINGS<br />
Exercise<br />
Determine the time required to clear<br />
an area 500 ft wide by one half mile<br />
long with two 335 hp dozers.<br />
Average no. trees/acre 630<br />
80% hardwoods<br />
• 1-2 ft dia. 120 • 3-4 ft dia. 5<br />
• 2-3 ft dia. 60 • 4-6 ft dia. none
LAND CLEARINGS<br />
Exercise<br />
Diameter is measured at breast height.<br />
This is usually taken as 4 ½ ft. If the<br />
tree has a buttress, diameter is taken<br />
where the trunk begins to run straight.
LAND CLEARINGS<br />
Exercise<br />
Step 1. Size of area<br />
500 ft wide by one half mile long<br />
Acres to be cleared =<br />
500 ft 5,280 ft ×<br />
2<br />
43,560 ft<br />
2<br />
/ acre<br />
⇒ 30.3 ac
LAND CLEARINGS<br />
Exercise<br />
Step 2. Size and number<br />
of dozers available<br />
Two 335 hp dozers
LAND CLEARINGS<br />
Exercise<br />
Step 3. Determine the average<br />
number of each size<br />
tree on a per acre basis.<br />
Average no. trees/acre 630<br />
• 1-2 ft dia. 120 • 3-4 ft dia. 5<br />
• 2-3 ft dia. 60 • 4-6 ft dia. none
LAND CLEARINGS<br />
Step 4. Basic production factors<br />
dozers.<br />
Exercise<br />
Table 7.3, 335 hp<br />
Base min./ac = 18.22<br />
M 1 = 0.2<br />
M 2 = 1.3<br />
M 3 = 2.2<br />
M 4 = 6.0
LAND CLEARINGS<br />
Exercise<br />
Step 5. Calculate time to clear<br />
one acre, equ. 7.9<br />
<strong>Clearing</strong> time =<br />
H A B M 1<br />
N 1<br />
1.3([2x18.22]+[0.2x120]<br />
M 2 N 2 M 3 N 3<br />
+[1.3x60]+[2.2x5])
LAND CLEARINGS<br />
Exercise<br />
Step 5. Calculate time to clear<br />
one acre, equ. 7.9<br />
<strong>Clearing</strong> time =<br />
1.3([36.44]+[24]+[78]+[11])<br />
⇒ 1.3(149.44)<br />
⇒ 194.27 min/acre
LAND CLEARINGS<br />
Exercise<br />
Step 6. Calculate total time<br />
Total time =<br />
194.27 min / ac × 30.3 ac<br />
2 dozers × 60 min / hr<br />
⇒ 49 hours
LAND CLEARINGS<br />
TRACTORS<br />
Tractors with rakes removing roots.
LAND CLEARINGS<br />
Equation 7.9 provides the time<br />
required to cut only. If the cut material<br />
must be piled use equ. 7.10.<br />
Rakes used<br />
for removing<br />
roots and<br />
limbs.
CHOPPERS<br />
Rolling choppers are used to kill<br />
undesirable growth. They are<br />
tractor towed.<br />
They are<br />
They are<br />
often used for<br />
clearing<br />
reservoir<br />
areas.
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