A
total
of
40,000
bank
cubic
yards
of
wet
earth,
that
weighs
3,050
Ib/BCY
with
a
25%
swell
percentage, needs
to
be
excavated
from
a
12’
deep
sediment
basin
with
an
elevation
of
1,100
FT
and
hauled
to
a
stockpile
location
2,700
LF
away
with
an
elevation
of
1,120
FT.
The
haul
roads
are
poorly
maintained
but the
superintendent
still
expects
50
minute
hour
efficiencies
for
the
fleet.
After
calculation
of
the
total
resistance
we
estimate
that
the
trucks
will
travel
at
17
MPH
on
average
along
the
haul
road
when
loaded
and
32
mph
on
average
when
empty.
The
superintendent
also
thinks
that
he
can
stage
the
trucks
in
order
to
maintain
a
60
degree
or
less
swing
and
a
1
minute
dump
time.
The
equipment
available
for
the
excavation
portion
of
the
project
would
consist
of
one
Caterpillar
345C
L
excavator
($175.00
per
hour
operated)
with
a
5
LCY
bucket,
a
24
second
cycle
time
(from
table
9.5
on
page
272)
and
a
bucket
fill
factor
of
105%.
The
excavator
also
has
a
23’ 9”
maximum
digging
depth.
You
also
have
as
many
Caterpillar
735
haul
trucks
($125.00
per
hour
operated)
with
low
tire
pressure
as
you
need
with
25.8
LCY
heaped
SAE
2:1
capacities
and
a
36
ton
rated
payload.
A.
What
would
the
production
rate
and
the
cost
per
BCY
to
haul
this
matieral,
rounding
up
and
down
the
number
of
trucks
to
integer
numbers
from
the
precise
balance
number?
B.
Which
of
the
two
options
(rounding
up
or
rounding
down)
would
you
choose
and
why?
Bucket
Capacity
5
LCY
Haul:
Truck
Capacity
25.8
LCY
distance
2,700
Excavator
Cycle
Time
0.4
min
(24 sec)
speed
17
mph
Dump
Time
1
minute
Return
Swell
25.00%
distance
2700
Efficiency
50
min/hr
speed
32
mph
Unit
Weight
Soil
3050
Ib/BCY
Material
Type
wet
earth
Excavator
rate
$175
Swell
%
105.00%
Truck
rate
$125
Adj
Bucket
Capacity
5.25
LCY
