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IntroductionFactors behind the selection of construction equipmentsTypes of construction equipmentsSelection criteria for various construction equipmentPlant and equipment acquisition
Good project management in construction mustvigorously pursue the efficient utilization of labor, materialand equipment. The use of new equipment and innovative methodshas made possible wholesale changes in constructiontechnologies in recent decades. The selection of the appropriate type and size ofconstruction equipment often affects the required amountof time and effort and thus the job-site productivity of aproject. It is therefore important for site managers andconstruction planners to be familiar with thecharacteristics of the major types of equipment mostcommonly used in construction.
Advantages of utilizing the construction equipments: Increase the rate of output through work progress withthe best effective and efficient methods. Reduce the overall construction costs especially forlarge contracts. Carry out activities which cannot be done manually or todo them more economically and much faster. Eliminate the heavy manual work by human thusreducing fatigue and eliminates various other hazards andhealth issues. Maintain the planned rate of production where there is a shortage of skilled or unskilled labor. Maintain the high quality standards often required by present-day design and specifications (technical
Economic Considerations Company-Specific Site-Specific Equipment-Specific Client And Project-Specific Manufacturer-Specific Labour Consideration
The economic considerations such asowning costs, operating labour costs andoperating fuel costs of equipment are mostimportant in selection of equipment. Besides, the resale value, the replacementcosts of existing equipment, and the salvagevalue associated with the equipment are alsoimportant.
The selection of equipment by a companymaybe governed by its policy on owning orrenting’. While emphasis on owning may result inpurchase of equipment keeping in mind thefuture requirement of projects, the emphasis onrenting may lead to putting too much focus onshort-term benefits.
Site conditions-both ground conditions aswell as climatic conditions-may affect theequipment-selection decision. For example, the soil and profile of a sitemay dictate whether to go for a crawler-mountedequipment or a wheel-mounted equipment. Ifthere is a power line at or in the vicinity of site,one may go for a fixed-base kind of equipmentrather than a mobile kind of equipment.
Construction equipments come with highprice tags. While it may be tempting to go for theequipment with low initial price, it is preferable toopt for standard equipments. Such equipments are manufactured in largenumbers by the manufacturers, and their spareparts are easily available, which would ensureminimum downtime. Besides, they can also fetchgood salvage money at the time of their disposal.
The owner/client in a certain project mayhave certain preferences that are not in line withthe construction companys preferred policies asfar as equipment procurement is concerned. The schedule, quality and safetyrequirements demanded of a particular projectmay in some cases force the company to yield tothe demands of the client.
A construction company may prefer to buyequipment from the same manufacturer againand again, and that too from a specific dealer. This may be to bring in uniformity in theequipment fleet possessed by the company orbecause the company is familiar with the workingstyle of the manufacturer and the dealer.
Shortage of manpower in some situationsmay lead to a decision in favour of procuringequipment that is highly automated. Further, the selection of equipment may begoverned by the availability or non-availability oftrained manpower.
Backhoes aremainly used to cleanup constructionareas, to dig holesin the ground, tosmooth unevenground, to maketrenches, ditchesand to help removedeep roots fromtrees.
Front shovel aremainly used forexcavation purposesabove its own track orwheel level.They are suitable forheavy positive cuttingin all types of dry soils.
They are usedfor bulkexcavation belowits track level inloose soils,marshy land andareas containingwater.
It consists of ahydraulically controlledbucket suspended from alifting arm. It is mainlyused for deep confinedcutting in pits andtrenches.
They are used formoving earth up to adistance of about100m and act as atowing tractor andpusher to scrapermachines. They canbe track-mounted orwheel-mounted.
Roller compactor is mainly used to for compaction ofearth and other materials in large works of highways,canals and airports.
They are used for site levelling, loading, hauling overdistances varying between 150m-900m. They maybe towed, two-axle or three-axle type.
It is used for horizontaltransportation ofmaterials on and offsites. Large capacitydumpers are used inmines and quarries.
It is used for gradingand finishing theupper surface of theearthern formationsand embankments.They usually operatein the forwarddirection.
The selection of earthmoving equipment is mainly dependent on the following factors: Quantities of material to be moved The available time to complete the work the job conditions The prevailing soil types, the swell and compaction factors, etc. The job conditions include factors such as availability of loading and dumping area, accessibility of site, traffic flows and weather conditions at site.
In order to plan the number of Earthwork Equipment needed, the planner first determines the following: The suitable class of equipment for earthwork-for example, if the soil to be excavated is loose and marshy, and bulk excavation is involved In the project, one may opt for a dragline. The appropriate model of equipment based on different characteristics such as payload of bucket and speeds required. For example, draglines come in different capacities ranging from 0.38 cum to 3.06 cum; scrapers in capacities ranging from 8 cum to 50 cum and so on. The number of equipment needed for the project to carry out the given quantity. The number of associated equipment required to support the main equipment
They are mainly usedfor weighing andmixing large quantityof concreteconstituents.capacity:-20cum/hr-250cum/hr
They are mainly used for mixingsmall quantities of concreteconstituents.capacity:-200lt/batch (small mixers)200-750l/batch (large mixers)
They are mainlyused fortransportingconcrete frombatching point.capacity:-3cum-9cum
They are used forhorizontal and verticaltransportation of largevolumes of concrete inshort duration.capacity:-30cum/hr (ordinaryconstruction)120cum/hr(specializedconstruction)
Selection of concreting equipment can be complicated and difficult. The decision will involve many issues that have to be analysed. The following factors are noteworthy: Site characteristics such as boundary conditions, noise limitations and other restrictions. Equipment availability-local availability of equipments, whether the contractor owns that equipment Continuity of operation Effect of permanent work Weather conditions Temporary works Time restrictions Concrete specifications
Concrete-mixing equipment selection will depend on factors such as the maximum and the total output required in a given time frame the method of transporting the mixed concrete the requirement of discharge height of the mixer.
Concrete-placement equipment selection depends on factors such as the capacity of the vehicle the output of the vehicle the site characteristics the weather conditions the rental costs, and the temporary haul roads.
It constitutes a group of equipment which areemployed mainly for lifting or lowering of unit loadand other . This group of equipment’s can be furthersub classified into:1. Hoists 2. Cranes Boom hoists DerrickCrane Chain hoists MobileCrane Electric hoists TowerCrane
Boom hoists are used tolift weights on the hooksthat are attached to thespecial metal ropesdesigned to bearmaximum loads.Boom hoist is mostlyused as industrialmachine where it loadsthe weight on containers.
Chain hoists are quitecommon example of hoistsystem and it can be seen atmost of the construction andindustrial purposes. Basically,chain hoist consists of chainrope and pulley that is used tomove the load from up todown.
Electric hoist ismodernized form ofchain and boom hoistmostly used in theindustries for fastworking. It is very much popularin material handlingindustries because itsaves labor costs byhandling maximum loadsat a time with no damagethreats.
Tractor hoist consistof a boom that isattached with baseof tractor and a hookwith rope is installedon this boom thatcan operatedthrough drivercontrols.
Cranes are considered to be one of the mostimportant equipment used in construction due totheir key role in performing lifting tasks all over theconstruction site.Plenty of crane models are available in differentshapesand sizes, though, they usually fall into threecategories,1. Derrick Cranes2. Mobile Cranes3. Tower Cranes
Factors affecting the selection of cranes are—1.Building Design 4.Economy Cost of move in, setup, and move out Building Height Cost for rent Project Duration Productivity2.Capability Power Supply 5.Site Conditions Soil Stability and Ground Conditions Load lifting frequency Access road requirement and site Operators Visibility accessibility3.Safety Operating Clearance Initial Planning and Engineering
• Adequate for all types of structures (up to 107 m)• Used for shorter projects duration (less than 4 months).• Not considered to be very safe due to lack of safety devices o limited switches to prevent overloading.• Can operate in muddy terrain but requires good ground conditions.• Needs adequate operating clearance.
• Preferable for high-rise (over 107 m).• Used for longer project duration.• Considered to be very safe due to the presence of limit switches.• Can operate where ground conditions are poor.• Does not need adequate operating clearance.
• Preferable for high-rise and apartment buildings.• Can be used for both long term and short term projects.• Cheaper than mobile and tower cranes.• Not considered to be safe.• Used when clearance is inadequate for the other units and sufficient space is unavailable for the erection of a tower foundation.
A construction company can acquire aconstruction plant and equipment through Cash or outright purchase Renting Leasing
Buying or financing equipment is mostsensible if the equipment is essential to yourcore fleet and expected to provide reliableservice for a long time. If you decide its worth the large outlay offunds to buy or finance equipment, youll findowning equipment can provide long-term taxbenefits--principally from deduction of interestexpense and depreciation of equipment.
Renting entails a short-term agreement or contract to use capital equipment weekly or monthly, with the rental rate decreasing as the term lengthens. Following are some other popular reasons for renting equipment:• To fill in for peak periods, special projects, or broken machinery• To try out equipment before buying or leasing it• To lessen the risk of purchasing costly equipment that won’t be needed later
Leasing can be an attractive option if youuse the equipment frequently but don’t have theresources to purchase equipment outright ormake an adequate down payment. However, leasing carries higher interest ratesand contractors usually are responsible for theinsurance and personal property taxes on theequipment being leased.
Introduction to Cost of Owning and Operating Construction Equipment Ownership cost Operating cost Effect of Depreciation & tax on selection of alternatives Equipment life & Replacement Alternatives Conclusion
The Plant, equipment and tools used in construction operations are priced in the following three categories1. Small tools and consumables2. Equipment usually shared by a number of work activities3. Equipment used for specific tasks Total equipment cost comprises two separatecomponents Ownership cost Operating cost
Ownership costs are fixed costs. Almost all of these costsare annual in nature and include: Initial Cost Depreciation Investment Cost Insurance Tax and Storage Cost
On an average, initial cost makes up about25% of the total cost invested during theequipment’s useful life. This cost is incurred forgetting equipment into contractor’s yard, orconstruction site, and having the equipmentready for operation. Many kinds of ownershipand operating costs are calculated using initialcost as a basis, and normally this cost can becalculated accurately. Initial cost consists of thefollowing items: • Price at Factory + extra equipment + sales tax • Cost of shipping • Cost of assembly and erection
The decline in market value of a piece ofequipment due to age, wear, deterioration andobsolescence. Depreciation can result from: • Physical deterioration occurring from wear and tear of the machine • Economic decline or obsolescence occurring over the passage of time In the appraisal of depreciation, some factorsare explicit while other factors have to beestimated. Generally the asset costs are knownwhich include: • Initial cost • Useful life • Salvage value
How ever, there is always some uncertaintyabout the exact length of the useful life of the assetand about the precise amount of salvage value,which will be realized when the asset is disposed.The Depreciation methods are • Straight line method • Sum of year digit method • Sinking fund method • Declining balance method
It is the simplest to understand as it makes the basis assumption that the equipment will lose the same amount of value in every year of its useful life until it reaches its salvage value. The depreciation in a given year can be expressed by the following equation Dn = (C – S) / NWhere Dn = Depreciation in year n C = The initial cost S = The salvage value N = The useful life (years)
It tries to model depreciation that actual market value of a piece of equipment after 1year is less than the amount predicted by SL method. Thus more annual depreciation in the early years of a machine’s life and less in its later years. The depreciation in a given year can be expressed by the following equation Dn = (year n digit) * (C – S) / ∑NWhere Dn = Depreciation in year nyear n digit = The reverse order C = The initial cost S = The salvage value N = The useful life (years)
The depreciation for a given year is calculated on the basis of the undepreciated balance (instantaneous book value), rather than the original cost. Further the method does not take into account any salvage value of the asset. The factor can be determined using simple interest formula and also special tables developed for the purpose. Dn = (M/N) * BVn-1 BVn = BVn-1 - DnWhere Dn = Depreciation in year n M = constant (Generally 2) N = The useful life (years) BVn-1 = Opening book value at year n
The method works in terms of a “sinking fund factor”, which is determined on the basis of the initial and salvage values of the asset, the service life and rate of (compound) interest. The factor can be determined using simple interest formula and also special tables developed for the purpose. Dn = (C – S ) * fWhere Dn = Depreciation in year n C = The initial cost S = The salvage value f = sinking fund factor N = The useful life (years)
Investment (or interest) cost represents theannual cost (converted into an hourly cost) ofcapital invested in a machine. If borrowed fundsare utilized for purchasing a piece of equipment,the investment cost is simply the interestcharged on these funds. If it is purchased withcompany assets, an interest rate that is equal tothe rate of return on company investment shouldbe charged.
Insurance cost represents the cost incurreddue to fire, theft, accident and liability insurancefor the equipment. Tax cost represents the cost of property taxand licenses for the equipment. Storage cost includes the cost of rent andmaintenance for equipment storage yards, thewages of guards and employees involved inmoving equipment in and out of storage, andassociated direct overhead.
The total equipment ownership cost iscalculated as the sum of depreciation,investment cost, insurance cost, tax and storagecost. This should expressed as an hourly cost andused for estimating and for charging equipmentcost to projects, it does not include job overheador profit. Therefore if the equipment is to berented to others, profit should include to obtainan hourly rental rate.
Ownership costs are also called “variable” cost.Because they depend on several factors such as thenumber of operating hours, the types of equipment used,and the location and working condition of the operation. Maintenance & Repair cost Tire cost Consumable cost Mobilization & Demobilization cost Equipment Operator cost Special Items cost
The effect of depreciation and taxes is keyfactor on selection of alternative equipments.
Once a piece of equipment is purchased and used, it eventually begins to wear out and suffers mechanical problems. At some point, it reaches the end of its useful life and must be replaced. The Equipment replacement decision involves determining when it is no longer economically feasible to repair. Equipment Life Replacement alternatives
Construction equipment life can be defined in three ways.Physical life: Age at which the machine worn out and can no longer reliablyproduce. Profit life: The life over which the equipment can earn a profit. Economic life: Time period that maximizes the profit over the equipment life.
The owners have to take replacementdecision in correct time to avoid losses. As thereare many factors involved, adopting the mostappropriate method is also important. Indetermining the optimum replacement timingsome analysis minimum cost, maximum profitand payback period are to be consider.
The selection of the appropriate type andsize of construction equipment and its operation,maintenance affects the required amount of timeand effort and thus the job-site productivity of aproject. It is therefore important for site managersand construction planners to be familiar with thecharacteristics of the major types of equipmentmost commonly used in construction.
Construction Project Management by KUMAR NEERAJ JHA Construction Equipment Management for Engineers, estimators, and owners by DOGULAS D.GRANSBERS Managing construction equipment by S.W.NUNNALLY Handbook of construction equipment maintenance by LINDLEY R.HIGGINS Construction Planning, Equipment, and Methods by ROBERT.L.PEURIFOY & CLIFFORD J.SCHEXNAYDER Modern Construction Management by FRANK HARRIS AND RONALD NCCAFFER www.google.com