By: Noel Jairo R. Barroga
There are two major components of engineering estimate material cost :
(a) Quantity and (b) Unit price. Quantity of materials, as mentioned in the preceding
sections, can be estimated with high degree of precision; hence, it does not pose a
significant problem in estimating job. On the other hand, unit price of material is
highly variable; it fluctuates from time to time.
Hence it is an important variable that Requires detailed evaluation in every estimate
job.
Due to significance of unit price in engineering estimate, it is a necessary for
construction companies and government infrastructure agencies or departments to
have their own cost monitoring team in charge of unit price analysis. If the estimator
can accurately predict the unit prices of all construction materials required in the
project, the estimate can be made reliable and effective undoubtedly.
With the availability of unit prices, unit cost for each estimated quantity can
be derived. The unit cost can be expressed in any of the following unit measures:
 Rolls, bundles, box, barrels, etc.
 weight ( kilograms, pounds)
 length ( inch, meter )
 area (m2, foot2)
 volume (m3, foot3)
The process of determining the cost of estimated quantity having two or
more materials expressed in units of area, volume, or length, etc. , is called as cost
analysis, A professional who is tasked prepare such costs analysis is referred to as
cost estimator or better to known as Cost Engineer.
Problem : Prepare a unit costs analysis per one cubic meter of concrete mixture
comprising of 9 bags of cement, 0.42m3 of sand and 0.84m3 of gravel. Assume the
following unit prices:
 Cement - P 120.00 per bag
 Sand - P300.00 per m3
 Gravel - P 500.00 per m3
Determine the total cost of every items in one cubic meter concrete mixture.
Cement - 9 bags at P 120.00 = P 1,080.00
Sand - 0.42m3 at P 300.00 = P 126.00
Gravel - 0.84m3 at P 500.00 = P 420.00
The unit cost per cubic meter is the sum of all the cost items.
Unit cost = 1,080 + 126 + 420 = P 1,626.00/m3
The unit cost of any estimated quantity can be derived in the same manner as demonstrated above.
The quantity survey and unit cost worksheets contain vital estimate data and
criteria; hence, they are important documents as ready references for checking or
examining and auditing purposes. For small construction projects, both the quantity
surveys and unit cost estimates can be done by a single estimator. But for large projects,
both quantity surveyors and cost estimators are usually involved side by side.
This team combination provides the way for specific task assignments with professional
responsibilities. It promotes transparency in engineering estimate where two or more
people are involved in a project with specific task.
The division and assignments of various works provide check and balance
measures for honest estimate. Consolidation of authority or power in one hand is
susceptible to abuse and corruption. Division of labor is appropriate for every
infrastructural project especially for government projects where such projects are
subject to technical audit review.
A well-prepared take-off and unit cost analysis are of great help for every
(technical) audit undertaking. Incomplete plans, vague specifications, or hasty cost
estimates are misleading while perfection in plans and specifications and
transparency in estimate promotes competency and integrity. For this reason, the
whole estimate job shall be divided and assigned to:
 Quantity Surveyor ... for bill of quantities
 Price canvasser ....... for unit price of materials, local labor rates
 Cost engineer ......... for unit cost of estimated quantities, equipment rental rates.
In addition to the direct costs, the cost estimator is task to compute the
indirect costs. These costs must also be estimated in detailed form to specify what
are included in the overhead. contingencies, and miscellaneous. The final total
indirect cost may be rounded to the nearest percentage of the total direct cost.
On the other hand, never use direct cost-percentage
method in computing indirect cost without detailing their
components or else this will lead to a guesswork or baseless
proposition. This is contrary to the primary purpose of reliable
estimating work. Computation based on theory is the core of
engineering estimate.
In comparison, the quantity survey and unit cost are
interrelated so that each of them must be prepared with high
"Practice is nothing without
degree of accuracy. It follows that if the price is inaccurate, the theory" - Descartes.
resulting cost estimate will deviate greatly from the actual cost
or most probable cost.
The situation is doubly aggravated if both quantity and unit cost are faulty. In such
situation, the purpose of estimating is defeated due to inefficiency or lack of a will to carry-out
a lengthy but accurate estimating procedures.
The estimate computations for quantity survey (bill of quantities) and cost analysis
(for materials, labor, and equipments) must be prepared in orderly manner. Such
estimate computations must be made part of the project’s documents, duly signed,
and sealed by all estimators involved who are licensed and qualified Cost Engineers
/ Civil Engineers bearing their Professional Regulation Commission (PRC) numbers.
The contents of the quantity survey and the unit cost sheets shall be combined to
have the estimate summary. It is the summary of estimate that contains the final
figures for the determination of the total direct cost. An estimated indirect cost shall
be added to the total direct cost to have the required "Most Probable Cost". An
example of summary of estimate is shown in Table 2.3.
The amount of each item can be computed by multiplying the estimated total
quantity and the corresponding unit cost. Similar table can be prepared for summary
of indirect costs. A sample computation for indirect costs is presented in Higher
Construction Estimate - Methods and Guide by the Author.
It is preferred, for transparency, to prepare two summaries of estimates, one for
direct cost, and another piece for indirect cost. The two estimates can be combined
to obtain the final summary of estimate to be used by the owner as reference for
bidding competition, or auditing and reviewing tasks. Transparency is a way to good
and honest estimate, which eliminates hidden agenda. Truth exposes the beauty of a
thing; a lie or deceit conceals ugliness, unfair motives, and corrupt practices.
Quantity Survey involves the estimate of quantities of materials or bill of quantities
that requires:
1. Precise calculations of volumes, areas, and lengths, weights, board feet, etc. Using
engineering mensuration principles, and
2. Proper use of "factors of waste" for materials that range from 1 to 5 per cent of the
estimated quantities. Greater allowance for waste may result to excessive estimate.
3. Estimated quantities shall be priced accurately by having at least three(3) price
canvasses carefully analyzed, thus, eliminating the outliners (overprices or
underprices).
4. Is the to lowest be made shall canvassed at be the included time price of for
canvassing. in a the piece estimated of But material for price deferred is the to take
best procurement, price into account if purchase price the allowance fluctuations of
prices from time to time.
5. Owners and clients are advised to seek a second estimate opinion of their projects
from qualified estimators with both competence and integrity to evaluate the final
submitted bid cost or lump sum proposal for possible human errors and/or estimate
frauds. Approval commands responsibility to examine, to conclude and to decide
based on facts or truth derived from accepted standard procedures.
NOTE:
Include separate
sheets for more
detailed estimate
computations, if
necessary.
Transparency - the
quality of something,
such as an excuse or a
lie, that allows
somebody to see the
truth easily (Oxford)
NOTE:
QS = Quantity Surveyor
L.P. = Labor Productivity
U.C. = Unit Cost
C.E. = Cost Engineer
NOTES:
A = Alpha Construction
Supply
B = K & Q Hardware and
Construction
C = Royal Trading and
Hardware
Labor and equipment productivity requires time-andmotion analysis.
The Author
MANUAL LABOR
Labor is either physical or mental effort that
provides the goods or services in an economy (Webster). A
physical work or a work that involves the use of hands is
called manual labor. A person who does a manual labor,
which usually involves hard physical work that is not skilled,
is called laborer, or a construction helper.
On the other hand, a person who does a manual labor that
requires skill is skilled laborer and the one that requires
special skill is specialty laborer.
Other laborers or workers that involves in
construction works are:
Foreman - a person in charge of a group of workers
regarding the whole operation in relation to job
performances.
Leadman - a skilled laborer with necessary skill and
experience to lead or in control of a particular work
such as mason leadman, carpenter lead man, etc.
Division of Labor
In building construction, manual labor is classified
with corresponding job description as follows:
Laborers -for hard works (assisting the skilled laborers)
like in earthwork, concrete proportioning and mixing,
transporting and curing, demolition, clearing and
grubbing and similar works.
Semi-Skilled Laborers - for rough works requiring
moderate skill like CHB laying, leveling and finishing
concrete surface, light welding, simple formworks
fabrication, installation and stripping, paint surface
preparation and similar works.
Skilled Workers - for fine works requiring high
level skill like cement plastering, tile setting,
painting, complex formworks, heavy welding of
steel trusses, columns, beams, finish carpentry,
ceiling, roofing, insulation and other same
works.
Specialty Laborers-for specialty works that need
technical and special skill like plumbing,
electrical, mechanical (pumps, and fire
protection elevator, escalator),communication
installation ,sophisticated concrete and steel
moldings, water proofing, landscaping,
sprinkler irrigation Specialty laborers must be
under the direct supervision of an experienced
and competent professional.
LABOR ESTIMATE
Labor estimate involves: Labor (a) determination of manhours and (b) application of labor wage. Labor man-hours can be
estimated by labor productivity while labor wage must conform to
minimum wage law prescribed by the Department of Labor and
Employment (DOLE).The main concern of the Estimator in labor
cost computation is the determination of the total man-hours
required to do a piece of work Labor man-hours are calculated by
"Labor Productivity Analysis.“
For purposes of discussion, labor estimate can be
expressed in terms of: (a) work quantity output and (b) work manhour rate. Work man-hour rate, Wmh is a measure of manpowertime required to accomplish a certain work. For example, 1.5 manhour per cu. m abbreviated as 1.5 mh/cu m. Work quantity output,
Wo expresses the capacity of workmen to complete a unit quantity
of work per unit time For example, 2.3 cu m per hour or 2.3 cu
m/hr. Work man-hour rate inversely proportional to work quantity
output; that is:
Wmh = 1/Wqo
Where:
Wmh = Work man-hour rate
Wqo = Work quantity output
But for simplicity, the following relations for labor estimate shall be established:
Labor Productivity, LP = Wmh man-hour rate . . m-hr / cu.m
Labor Output, LO = Wao , work quantity output . . cu m / m-hr
LP = 1/LO
In strictest sense, labor estimate computation must contain the following information:
 The total number of manpower required to do a job.
 The total working time in terms of man-hours or man-days to complete the job.
 The corresponding labor rate per hour or day prevailing in the jobsite, which
includes salaries, wages and fringe benefits prescribed by the Department of
Labor and Employment.
 The total cost of labor derived from the required manpower, prevailing labor rates,
and work duration to complete the work.
The overall result obtained from Labor Productivity formulas can differ from
the situation in the real construction site. The purpose of LP is to enable the estimator
to develop a clear idea at the theoretical level of the labor estimate. The estimator
must be able to start with aqualified estimate solution with acceptable accuracy and
reliability.
Then, he transformed the theoretical calculated results with sound judgment to
achieve the most probable values to be encountered in the field.
WAGE RATES
For every manual labor, there is a corresponding wage rate that must
conform to the regular wage rates determined by DOLE. Normally, DOLE stipulates
daily minimum wage rates for ordinary laborers in every region.
These wage rates shall be the basis for labor cost estimate. For estimate purposes,
the prevailing daily minimum wage rate shall be adjusted to determine the daily
basic pay of the different divisions of manual labor by the expression,
Basic Pay - Rw x Minimum Wage Rate
Where Rw is construction wage rate factor with suggested
values as follows:
Note:
Living wage - a just
wage that can
sustain a decent
living for the worker
and his family in
relation to the basic
needs of life.
A specialty work demands an expert or a master of trade. Expertise commands a
higher pay in consideration to technical or special skill. Likewise, skilled laborers
deserve higher pay for their competence. The standard of living is higher in urban areas
than in the country side (Rural).
Therefore, laborers in urban areas deserve higher wage rate factors to defray high prices
of basic needs - food, water, electricity, transportation, room rental rate, etc. Every
construction worker must be paid based on what his labor is worth. Labor justice strictly
demands fair works, right position, and just compensation. Minimum wage rates must be
set to provide a fair living? wage. Likewise, other wage rates, depending on trade
classification, shall be stated as a safeguard against excessive, unreasonable, exorbitant
profit and excess cost.
Every estimator is bound by duty to prepare a labor estimate in conformity and
in compliance with the daily minimum wage rates mandated by labor law. A wage rate
below the stipulated minimum wage rates is illegal; it is a way to labor slavery. On the
other hand, a wage rate which is too high from the legal minimum wage rates, or
accepted standard wage rates will result to excessive estimate, It yields unlawful gain that
shapes the atmosphere of corruption in labor cost estimate.
PERFORMANCES OF WORKERS
Labor productivity is extremely difficult to derive because it involves many
factors. However, there isa need to establish computational methods in deriving
labor productivity expressed in man hours for estimate purposes. The estimated
value may not be exactly equal to actual labor output. But probable values can be
accepted when true values are complicated or difficult to obtain. The best way of
acquiring labor production is to base the work time from established data taken from
actual field observations or experiences. In the absence of such field observations,
the Estimator may compute labor productivity in relation to time and motion
considerations.
Performances of workers are dependent on many factors such as those enumerated
by Berger/Gödel:
 The type of the work
 The availability and capability of skilled labor
 Weather condition
 Construction supervision and management, and
 Construction scheduling
Effective management raises employee productivity by properly and
systematically coordinating construction-related operations. Workers are
encouraged and supported by good management, which encourages them to
complete more tasks earlier than expected. The expected number of labor hours is
used to determine the construction timetable. Improper construction scheduling
results in job activities that are in conflict with one another or overlap, which can
lead to delays or slowdowns.
The labor output is impacted by these idle hours. The estimated labor-hour time
duration should be used as a guide when creating the construction schedule in order
to reflect the real job site condition. A construction timetable created based only on
educated guesswork is careless or ineffective. The Estimator is "obligated to
exercise a high level of awareness of building methods and difficulties and
conditions due to these combined elements and conditions affecting labor
productivity .
Labor productivity analysis is a procedure in determining the required probable
work time or man-hours in accomplishing a job. Work time can be estimated in four
basic stages:
 Breaking the job into its sequence of steps,
 Determining the required reasonable time to complete the job step,
 Summing up all the individual work time,
 Adjusting the nominal work time taking into consideration the workmen efficiency,
job effectiveness and actual job conditions to estimate the probable work time,
which is referred to as "estimate work time" that will be applied in labor
productivity.
A job step is defined as a segment of the entire job necessary
to progress the work. It is important to keep the job steps in
their correct sequence. Any out of order job step may
introduce erroneous work time.
Each job step shall be recorded in sequence with
corresponding work time. This part of the labor analysis is
usually prepared by knowing, or preferably by watching the
workers do the job. The job should be observed during normal
times and situations in order to record the actual usual work
time.
Problem:
Determine work total work time in hauling 200 pieces, 150 mm CHB withthe
following estimate data: (a) hauling distance, 200 meters; (b) hauling equipment,
wheelbarrow, 8piece capacity per trip; (c) walk travel speed, 35 meters per minute (or
2,100 m/hr - assumed ).
SOLUTION:
1. Work activities and work time. Assume one - man work.
 Load CHB . . . 8 x 15 = 120 sec per trip
 Travel . .. (200/35) x 60 = 342.8 sec
 Unload CHB . . . 8 x 15 = 120 sec
 Return travel . . . (200/35) x 60 x 0.85 = 291.3 sec
Work cycle time = 874.1 sec
Return travel time is reduced by 15% because wheelbarrow is empty in going
back; as a result, the travel is easier and faster.
Nominal work time (total) = (200/8) x 874.1 = 21,852.5 sec or 6.07 hrs
Nominal Labor Output, LOn = 200 CHB/6.07 hrs = 32.94 CHB/hr (one man)
Nominal Labor Productivity, LPn = 1/LOn = 1/32.94 = 0.03 m- hr/CHB
The computed theoretical work time in Ex.3.1 suggests a continuous 60
minute work hour or 100% job effectiveness, a condition that is never achieved in
reality. This theoretical work time is called "nominal work time ". The word nominal is
defined as "something in name only, and not in reality - Oxford. The nominal work
time must be modified by using labor adjustment factors to reflect actual job
situations. This will be discussed in the following topics.
Caution must be exercised to combine manpower having the same labor rate.
Almost all labor activities in project construction involve a team work; that is, the
employment of a combined skilled and unskilled laborers working together. Wages
for skilled workers are higher as compared to helpers (non-skilled laborers). This
difference in labor wages needs careful analysis in labor cost estimate.
Labor productivity is dependent on:
 Workmen capability or efficiency
 Job conditions
 Job effectiveness
Workmen capability or efficiency
Skilled and experienced workers perform more effectively than non-skilled or
inexperienced laborers. Workmen efficiency reflects speed and accuracy of
workers, which is dependent on skill and experience, work schedule, supervision
etc. Lack of construction scheduling, lenient work management of insufficient supply
of materials reduces workers' output. The efficiency of workers reflects the
managerial capability of the contractor-builder. Below average rating results to slow
and poor work performances, hence, it should not be used in engineering estimate.
Sloth is deterrence to labor productivity. For labor estimate purposes, minimum
workmen efficiency shall be 0.85 representing an average value. Poor or slow
workers are unfit on the job; hence, they should not be employed in a project
construction. They should improve their skills through training and proper
motivation.
Job conditions
Job conditions like obstruction, rugged terrain, hard soil, water table, space
restriction, etc. adversely affect workers' output and would get slower as conditions
become less favorable. The estimator must evaluate the actual conditions of the job
and use appropriate labor factors to define what is "easy" or "hard" job.
Job effectiveness
Job effectiveness considers effective or productive work duration. Normally, one
workday is an eight-hour activity with a total 30 minutes break-time. In this case,
actual working time is 7.5 hours. In addition to break-time, some necessary delays
are often encountered during the work which can significantly reduce the actual
eight-hour working time per day.
LABOR ADJUSTMENT FACTOR
NOTES:
Workman efficiency depends on:
skill and experiences - job training and working
attitude
supervision and management - strict or relax,
systematic or unplanned - Job condition: space
restrictions - wide or limited working area, at
Ground level or higher floors.
Job effectiveness accounts for delays due to:
weather - hot or rainy days
availability of materials, tools, service vehicles,
and equipment Figures in parenthesis are range
average values.
35/60 job effectiveness may be used for highly
restricted work place, or severe site condition.
Problem:
Determine the total labor adjustment factor for an averus" carpenter with
45/60 minute per hour job effectiveness assigned to a work under above average
job condition, Use Table 3.1.
SOLUTION:
Total Labor Correction Factor, Cw
Ew = 0.85 (average)
Ej = 0.75 (45/60 minute per hour)
Cj = 0.92 (above average value)
Cw = 0.85 x 0.75 x 0.92 = 0.586
Where:
Ew = Workmen Efficiency
Ej = Job Efficiency
Cj = Job Condition
Some people compute labor cost equivalent to a certain percentage of the material cost.
This Labor-Material Percentage usually ranges from 20 (for simple jobs) to 35 (for
average work) for ordinary work conditions. For specialty works, the percentage may
reach 60% or even higher. As illustrative example, a certain cost item having a material
cost of P 100,000.00 will entail a labor cost equal to P 35,000.00, assuming a 35
percentage labor-material factor. This method of computing labor cost is highly
approximate and should not be accepted as a basis for final labor cost for a particular
item of work unless proven reliably by past records of actual work performances. Actual
labor output observed from experience shall be supported by numerical work time
analysis which will serve as the basis of estimate for transparency and/or justice.
However, the Labor-Material Percentage Method may be used to approximate the total
labor cost of a project by considering the total cost of materials;
Approximate Total Labor Cost = 0.40 x Total Cost of Materials
For Example:
The estimated total cost of material for a low-cost housing is
P385.450.00.Theapproximatetotallaborcostis:0.40 1385.450 - P154. 180. This is vague
information for contract agreement It can cause ill-will and disputes during
construction(no work detail).
To enter into construction contract regarding labor cost without detailed labor cost
computation is a risky undertaking. A factor that makes engineering estimate reliable and
distinct from layman’s estimate is detailed cost analysis, a product of analytical,
knowledgeable technical mind.
Labor cost computed from Labor Productivity Method expressed in man-hours, is more
precise than Labor-Material Percentage Method (LMP).For illustration, a door lock that
costs P 250.00 was estimated to have 0.35 x 250 = 87.50 labor cost for installation.
Suppose the same door undergoes a change indoor lock specification. It retains the same
form but of different brand with higher cost of P 1,500.00. In this case, the new labor cost
is 0.35 x 1,500 = 525 The increase in labor cost is unjustifiable, unacceptable because the
amount of installation work for the two door lock sets having identical form is the same
and did not change.
Machine is an instrument with moving parts for transmitting force or
motion designed to do a particular job. On the other hand,
equipment is a machine that is needed for a particular activity or
purpose like: office or kitchen equipment, or construction
equipment.
Equipment evaluation requires determination of: (a) equipment
production and (b) rental rates. If the estimator can predict
equipment production accurately, which is dependent on cycle time
and other factors, construction cost for equipment can be estimated
reliably.
Equipments were designed and built for specific use or purpose.
Therefore, there is right or appropriate equipment for every kind of
work. The proper choice of equipment depends on: (a) The quantity
of material or volume of soil to be worked, (b) The type of soil to be
moved or material to be lifted and (c) Job conditions.
Small quantity of earthwork requires minimum size machine. Unpacked earth, sand,
and gravel are easier to dig than tough dry clay or rocks which require bigger and
more powerful equipment.
Cycle time is a factor for equipment production. The type of soil affects cycle time of
excavating equipment. Total cycle time is dependent on machine size. Small
machines can cycle faster than large machines. In addition, with excellent job
conditions (no space restriction),machines can cycle fast. As job conditions become
more severe, the machine slows down accordingly; that is, getting slower as
conditions become less favorable.
Another important consideration in equipment selection is mobility. A wheel-type
excavator moves faster than track-type. It can travel to and from the job site by itself
(no trailer) without damaging paved surface.
However ,when the application does not need a lot of travel to and from, and around
the job sites, a track-type excavator could be the better choice for some reasons: (a)
it provides good traction and floatation, (b) excellent maneuverability, (c) good
overall stability and (d) faster machine repositioning, require proper evaluation:
Tracks
 Floatation
 Traction
 Maneuverability
 Severe underfoot
 Faster machine repositioning
Wheels
 Mobility
 No pavement damage
 Better stability with outriggers or dozers
 Leveling machine with outriggers
 Dozing capability
Problem:
Determine the estimated appropriate quantity excavating of 1,200 equipment cu.m ordinary for excavation with soil.
SOLUTION:
Trial 1: Given Data
Equipment - Flywheel Horsepower: 54HP, Track-type
Production - 42 x 45/60 = 31.5 cu.m/hr Rental rate - P 575/hr
Mobilization/ Demobilization - P 8,000
Equipment time = 1,200/31.5= 38hrs
Equipment cost = 38 x P575 + P8, 000 = P 29,850
Trial 2. Given Data
Equipment - Flywheel Horsepower: 89HP, Track-type
Production - 63 x 45/60 = 47.25 cu.m/hr
Rental rate - P 750/hr
Mobilization/ Demobilization - P 8,000
Equipment time = 1,200/ 47.25 - 25.39 say 24 hrs Equipment cost = 24 x P 750 + P8, 000
= P 26,000
Construction equipments are classified according to their uses. The most common
types are given below . All machines were designed and assembled for specific
intended purpose. Make sure to choose and put the right equipment on the job. The
estimator should determine the equipment output or capacity based on the
manufacturers' specifications, not by guesses.
Earth moving equipment - used for bulldozing, ripping, and land clearing
 Tractors (crawler or wheel type)
 Loaders (crawler or wheel type)
 Scrapers (motorized or towed type)
 Graders (motorized)
Excavating equipments - used to excavate earth and rock.
 Backhoe (hydraulic, crawler or wheel mounted) Backhoe loader
 Power front shovel
 Draglines or rope excavators
 Clamshells
 Trenchers
Hauling equipment - used in handling and transporting earth, aggregates, rocks and
other materials. - Dump Truck
 Cargo Truck
 Wagons
 Trailers (high and low bed)
 Belt conveyors
Compaction equipment - used in compacting soils. Tamping rollers





Smooth-wheel rollers
Pneumatic-tired rollers
Vibrating steel-drum rollers
Vibrating plate (manual)
Propelled compactors (manual)
Lifting equipments - used in lifting and placing loads.
 Cranes (crawler, truck mounted, hydraulic)
 Hoist and tower cranes Forklifts
Concreting equipment - used in mixing and placing concrete.




Concrete mixers
Transit mixers
Concrete pump and grout
Concrete paver and finisher
Pile-driving equipment - used to drive piles.
 Pile hammer (without crane)
 Drop hammer
 Pile driver (vibratory)
Drilling equipments - used to drill hole in rocks.
 Jack hammer
 Drills (rotary, percussion)
Air equipments - used in construction projects involving drilling rock loosening
earth and cleaning.
 Air compressors
Pumping equipments - used for removing water from excavations and supply water.
 Pumps (low and high pressure type, sump pump, mud pump, hydraulic)
Asphalting equipments - used in asphalting pavements.
 Asphalt distributor
 Asphalt repaver Asphalt paver
 Asphalt remixer
 Pavement profilers
Crushing equipments - used in the production of crushed stone aggregates.
 Aggregate crushers
Power generating equipment - used to generate power.
 Generator sets
Shop equipment
 Welding machines
 Shop machines
Hydraulic Excavators utilize hydraulic pressure to
develop bucket digging penetration into material
are classified as "hoes". There are two types of
hoes:(a) front shovel and (b) back shovel or back
hoe. Front shovels are used primarily for digging
soil above track level and loading hauling trucks.
They require strong soil material to cut which can
stand with vertical surface. Backhoe is used mainly
to excavate soil below the natural surface of the
ground where the machine rests. Hoes are either
crawler or wheel mounted. Crawler mounted hoes
have very slow travel speeds of about 4.5 km/hr.
Every machine was modeled,
designed, and built based on its
specifications. Excavator's
specifications include: (a) flywheel
power (b) operating weight, (c) bucket
capacity, (d) maximum drawbar pull,
(e) maximum travel speed, (f) ground
contact area, (g) fuel tank refill
capacity, (h) shipping dimensions and
(i) operating range dimensions, among
others.
Flywheel is a heavy wheel in a machine or an engine that helps to keep it working
smoothly and at a steady speed (Oxford).
Operating Weight includes 50% fullfueltank,operator75kg (165 lbs.), one piece
boom, long stick and bucket, standard track shoes and optional counterweight, if
available.
Maximum drawbar pull is the available pull which a crawler tractor can exert on a
load. It is a prime consideration in choosing equipment for particular type of work.
Hard soil and heavy material requires stronger machine in digging and lifting
operations; hence greater drawbar pull is required.
Maximum travel speed is vital information in making a decision whether to transport
the machine by using haulers or by operating the equipment to travel by itself, if the
job site is considerably of short distance with good road, to eliminate mobilization
and demobilization
Ground contact area is a prime consideration where there is space restriction in the
job site. The estimator must figure out the Ox mobility of equipment during
operation for production estimate. Small machines can cycle faster than large
machines especially in limited working areas.
Fuel tank refill capacity is a factor in determining idle time. With known fuel refill
volume, one can estimate the duration of equipment working operation and the time
interval for refueling which in entails idle time. quire
Bucket capacity. Excavator earthmoving production depends on: (a) bucket capacity,
(b) cycle time and (c) job efficiency. The estimator should be able to predict these
three factors with precision in order to by estimate machine's earthmoving
production reliably for a particular project.
Reference: Caterpillar Performance
Handbook Legend:
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Maximum Loading Height of Bucket
Maximum reach at ground level
Maximum digging depth
Maximum height to bucket teeth
NOTES:
Operating weight includes coolant,
lubricants, full fuel tank, standard shoes,
bracket and operator (75 kgs).
Actual bucket capacity (heaped) shall be
determined according to the bucket model,
type, bite width to be used. Consult bucket
specification supplied by manufacturers.
Maximum travel speed shown in the table
are for crawler type excavators. Wheel-type
can travel five (5) times faster than crawler
type.
Ground contact area includes standard shoe
and standard under carriage. - Conversion:
1 gal = 3,785 liters
Model Class – Small
Model Class – Medium
Model Class – Large
Model Class – X-Large
Shipping dimensions are useful
in determining the length and
width of trailers in transporting
the equipment. Longer trailers
involve higher rental rates.
Estimators are tasked to
prepare reliable estimates.
LEGENDS:
A - Cab height
B - Transport width
C - Track width
N - Track height
O - House height
H - Overall transport
length
G - Overall track length
J - Transport height
Backhoe has many uses: (a) to excavate trenches, footings and pits for
basements, (b) grading work, (c) loading hauling trucks and (d)
hauling or lifting pipes in drainage works.
God bless us all!