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Fundamentals of Construction Estimating, 3rd edition_下.pdf
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CHAPTER10—PRICINGEXCAVATIONANDBACKFILL233Someestimatorsprefertousemethod(a)becauseitleavesthetakeoffquantityunchanged.Othersprefermethod(b)becauseitreflectstheactualquantityofsandthatneedstobeordered;eptable.Wherethesupplyoffillmaterialisquotedasapriceperton,hepricepercu.yd.bankmeasure.Forinstance,ifapriceof$10.00pertonisofferedforthesupplyofpitrungravel,pactedpitrunfromFigure10.2,thepricepercu.yd.canbecalculatedthus:pactedCu.Yd.(lbs)Pricepercu.yd.=Priceperton×———–––––———––––————–-2000lbspertonSo,inthiscase:3650Pricepercu.yd.(BankMeasure)=$10.00×—–—2000=$18.25Ifapricepercu.yd.ofloosematerialisrequired,then,ofcourse,theweightofaloosecubicyardisusedintheprecedingformula.CalculatingTruckingRequirementsIntheexamplesthatfollow,heoptimumnumberoftrucksrequiredtotransportexcavatedmaterialsandgravels.Asimpleformulacanbeusedforthiscalculationbasedonthepremisethatitisdesirabletohavesuffi-cienttruckingcapacitytoensurethattheexcavationequipmentisabletooperatecontinuouslyandnothavetowastetimewaitingfortrucks.Clearly,threetruckswillberequiredifittakes10minutestoloadatruckand20minutesforthattrucktounloadandreturnforanotherload,because,whilethefirsttruckisaway,twoothertruckscanbeloaded.Fromthisintuitiveanalysis,thefollowingexpressionisobtained:UnloadingTimeNumberofTrucksRequired=————––——+1LoadingTimewhereUnloadingTime=Round-TripTravelTime+TimetoOff-loadtheTruckandTruckCapacityLoadingTime=———————LoaderOutputandCapacity(Loose)TruckCapacity(BankMeasure)=—————–——1+SwellFactorNotethatthenumberoftrucksobtainedfromthiscalculationshouldalwaysberoundedupnomatterhowsmallthedecimal.Thisisbecausetorounddown,evenasmallfractionmayresultinashortageoftruckcapacity.upied.Copyright2010CengageLearning.AllRightsReserved.Maynotbecopied,scanned,orduplicated,inwholeorinpart.Duetoelectronicrights,somethirdpartycontentmaybesuppressedfromtheeBookand/oreChapter(s).Editorialreviewhasdeemedthatanysuppressedcontentdoesnotmateriallyaffecttheoveralllearningexperience.CengageLearningreservestherighttoremoveadditionalcontentatanytimeifsubsequentrightsrestrictionsrequireit.CHE-PRATT-09-1201-010.indd2334/29/103:50:34PM234CHAPTER10—PRICINGEXCAVATIONANDBACKFILLAlso,thismethodofcalculatingthenumbertrucksrequiredisbasedontherebeingasufficientamountofmaterialtojustifytheuseofafleetoftrucks.Whereonlysmallquantitiesofmaterialaretobetransported,oneortwotrucksmaybeallthatisneededtomovetheentirequantityofexcavatedmaterialregardlessoftheoutputoftheexcavatorandtheothervariables.Forexample,ifthereisatotalofjust20cu.yd.(bankmeasure)ofexcavatedmaterialtoberemovedfromasite,andthecapacityoftrucksis10.5cu.yd.(bankmeasure),then,clearly,twotrucksareallthatisneeded.iventheoutputoftheexcavator,thespeedofthetrucks,andthedis-tancetobetraveledbythetrucks.EXAMPLE:GRAVELSUPPLYPRICINGCalculateapriceofobtaininggravelfromapitlocated16milesfromthesitewherethereisapitroyaltyof$2.50percu.yd.,usinga1.5cu.yd.trackloaderatthepittoloadthegravelatarateof50cu.yd.(bankmea 内容来自淘豆网www.taodocs.com转载请标明出处.
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  • 时间2012-05-26